Google

Wednesday, May 2, 2007

Breeding Centipedes

Breeding Centipedes

It is extremely difficult to tell an adult male centipede from a female. Since centipedes are rapacious predators and are cannibals as well, breeding can be a risky affair in captivity, and often the only way to determine if a breeding pair is compatible is to introduce them to each other and hope for the best.

Centipedes mate in the manner typical of many arthropods -- the male produces a packet of sperm called a spermatophore, which is taken up by the female and stored in a pair of internal sacs known as spermathacae, where it is used to fertilize her eggs. In some species, the spermatophore is inserted directly into the female's body by the male; in most, the spermatophore is simply left lying on the ground where it is later found and picked up by the female. Females are capable of maintaining live sperm in their spermathacae for a considerable length of time, and can still lay viable eggs over six months after their last mating.

A typical clutch will contain between 20 and 60 eggs. In the scolopendromorph centipedes, the female will curl protectively around the egg clutch and defend it against predators. She will also periodically lick the eggs to prevent fungus from growing on them. The eggs hatch in about a month, and the young centipedes remain close to their mother for another month or so before dispersing.

The scolopendromorphs and geophilomorphs have a pattern of growth known as epimorphosis, which means that the young are born with their full number of body segments. The scutigeromorphs and lithiobiomorphs, by contrast, undergo anamophosis. They are born with fewer segments than adults and continually add segments to their body with each molt until they are full grown. Large centipedes can take as long as three years to reach sexual maturity. Once they reach full size, they can continue to molt, but will not add any more body segments.

Handling a Centipede

Handling a Centipede

The painful results of a centipede bite have been well known for centuries. In 1740, the English naturalist Charles Owen wrote, "The Scolopendra is a small venomous worm, and amphibious. When it wounds any, there follows a Blueness about the affected Part, and an Itche all over the Body, like that caused by Nettles. Its Weapons of Mischief are much the same as those of the Spider, only much larger; its Bite is very tormenting, and produces not only pruriginous Pain in the Fleshe, but very often Distractions of the Minde."

The venom apparatus consists of modified legs, on either side of the body just behind the head. These are known as maxillipeds, or sometimes as forcipules. The fang itself consists of a hollow tube with a sharp tip, like a hypodermic needle. The venom glands are found inside the body wall at the base of the fangs. When the centipede attacks, muscles surrounding the venom gland squeeze it and force venom through the hollow maxilliped and into the prey's body.

Very little scientific study of centipede venoms has been done, but it is known that some centipede venoms contain the active ingredient 5-hydroxytryptamine. The venom of the North American giant centipede, Scolopendra heros, contains cytolisins which break down cell walls.

Smaller centipedes, such as the orangish Scolopocryptops specimens found under rocks throughout the northeastern United States, produce nothing more than a painful but localized reaction, similar to a bee sting. The larger tropical species found in the pet trade, however, pack more of a punch, and can produce systemic symptoms as well as severe pain at the site of the bite---some people bitten by tropical scolopendromorphs have suffered nausea, vomiting, headaches and swelling in the lymph nodes. The centipede's venom can sometimes have a necrotic effect at the site of the bite, which can produce a painful open sore that takes some time to heal.

There is only one case in the scientific literature of a human death caused by a centipede bite -- a seven year old girl in the Phillipines died after being bitten on the head by a fullgrown tropical centipede, probably the large species Scolopendra subspinipes. Despite the potential danger, however, centipedes are not considered to be a major medical concern in any of the areas where they are found. Nevertheless, be aware that your pet centipede is a venomous animal, and treat it with the respect it deserves. A small percentage of people are allergic to centipede venom, and for these people any bite, no matter how small the pede or how weak the venom, can turn into a life-threatening emergency. If you are allergic to bee stings, the chances are good that you will also experience a reaction to centipede venom.

All of the tropical centipedes should be treated with caution. They should not ever be touched or handled with bare hands. If it is necessary to handle one, to move it to another tank for instance, great care should be exercised. These animals can move very quickly and bite readily, and unlike other animals that move rapidly away from potential danger, centipedes will immediately go on the attack towards any perceived threat.

Smaller centipedes are rather delicate and should be moved carefully. The best method is to place a small container (such as a deli cup) into the tank and then "herd" the centipede into it using an artist's soft-bristled paintbrush. Once the centipede runs inside the container, snap the lid on and it will be safely confined. This method can also be used (with more care) for larger tropical centipedes. To prevent escapes, transfer operations should always be carried out in an enclosed area to prevent the centipede from getting away if it makes a break for it. A bathtub works well (make sure you plug the drain). Keep all of your fingers well out of the way. If you offer a centipede any chance to get a fang into your flesh, it will happily oblige.

Some keepers handle their centipedes using a long pair of tongs or forceps that have been padded at the tips with foam rubber (a method also used to handle scorpions). If the tongs are at least twelve inches in length, the centipede will not be able to reach up and bite you with its fangs. This method should not be used by beginners, however---the exoskeleton of a centipede is not as thick as a scorpion's, and too much pressure can rupture the centipede's body wall and cause death. Centipedes also move very quickly, and it may be very difficult to grasp the pede without causing it to shed a large number of legs. It is far safer for both you and the centipede to prod it into a suitable container using a brush.

It may be best to slow down the centipede somewhat before attempting to move or handle it. This can be accomplished by placing the entire centipede tank in the refrigerator for about fifteen minutes. Centipedes, like all arthropods, are ectotherms and are dependent on their external environment for body heat. The cooler the temperature, the less quickly they are capable of moving. Keep in mind, however, that your centipede is a tropical animal, and cooling it to unnaturally low levels like this will cause it considerable stress. It may also kill the animal if cooled too far or too long. The idea is to cool it enough to slow down its movements, not to immobilize it.

Housing a Centipede

Housing a Centipede

Housing for a captive centipede is not a complicated or expensive affair. Any pet shop will have all of the materials needed to keep a centipede happy and healthy.

An ordinary tropical fish aquarium makes a good home for any of the tropical centipedes. A five gallon aquarium will be suitable for a younger specimen, while a ten gallon aquarium provides adequate space for even the largest of the giant centipedes. As a rough rule of thumb, you will want a tank that is at least as wide as your centipede is long, and at least one and a half times as long as the length of the centipede

Fish tanks have several advantages -- they are easily obtained and inexpensive. They hold humidity well and make it easy to keep your centipede's environment properly damp. They can be made secure and virtually escape-proof. And they resist scratching and offer a good view of your pet. Since your centipede tank will not contain any water, it is still suitable even if it leaks at the seams or has a cracked bottom. Used leaky aquariums can often be found at garage sales, or your local pet shop may have some that they want to get rid of.

Your centipede's cage will need a tight-fitting lid to prevent escapes. Centipedes are not capable of climbing up the smooth glass or plastic sides of an aquarium, but they can climb up the corners using the bead of silicone glue that holds the aquarium together. They can also make their way up along any plants, branches or electrical cords that are placed inside the tank.

The commercial fluourescent hoods that are used with fish tanks are not suitable for a centipede tank. They cannot be secured and offer many gaps and cracks that the centipede can wedge its flat body underneath, allowing an easy avenue of escape. Your centipede is an accomplished escape artist, and if there is any way out of its tank it will eventually find it: the last thing you want is a ten inch long aggressive venomous centipede loose somewhere in your house. The cage must be provided with a secure screen lid.

There are a number of different types of screen lid available for aquariums. The best kind for centipedes are the screen mesh lids with the metal clips to hold them on tightly. Make sure the wire mesh is tight enough to prevent the centipede from squeezing through the holes. Note that the sharp wires used in these cages do present a potential danger to the centipede, which can sometimes cut its exoskeleton on these wires and bleed to death.

Another type of aquarium top uses a perforated metal sheet with two turning latches to hold it on. This type is not suitable for keeping centipedes---the metal is too flexible in the middle and a determined centipede will be able to wedge its head between the lid and the aquarium rim and escape.

The best option for housing a pet centipede is one of the clear plastic sweater boxes that can be found in any department store. These come in a variety of different sizes, and all have their own lids that snap on securely. They are also lightweight and take up a bit less room than an aquarium. Another advantage of the sweater boxes, particularly if you will be keeping a number of invertebrate pets, is that they can be securely stacked atop one another to put a large number of cages in the smallest possible area. One disadvantage of the sweater box, however, is that the plastic isn't as clear as glass, which may make your pet difficult to see. Another disadvantage is that large centipedes may be able to reach up and pull themselves over the edge of the tank, presenting a potential escape danger while you are cleaning the tank or moving the centipede. For safety's sake, the cage should be at least as deep as the centipede is long.

Sweater boxes must be modified a bit before they make a suitable home for your centipede. You will need to drill a number of airholes for ventilation, along the top and bottom edges all around the box. This can be done with a hand drill, or the holes can be carefully melted through with a heated screwdriver or soldering tool. The holes should be no larger than half the body width (not the legspan) of the centipede, to prevent escapes. If your centipede cage does not have adequate ventiliation, the warm damp conditions will encourage mold and fungus growth that will ruin the cage and present a danger to your centipede. Also, if the humidity level is too high, it will interfere with the diffusion of air into the trachea.

The final option for housing your centipede is one of the plastic "critter cages" that can be found in pet stores. These are available in a variety of sizes. Make sure you get a model that has little latches to hold the lid on securely---the cheaper versions have flimsy snap-on lids that often come apart whenever the cage is picked up by the handle.

Whichever type of cage you choose, there is one rule that you absolutely must follow when housing centipedes---all centipedes are cannibals, and all will happily eat any other arthropod that you place in its cage, including members of their own species. All of your pet centipedes will need to be housed individually in its own cage. If you place two of them together, you will sooner or later end up with one (very well fed) centipede.

Substrate

Centipedes, unlike many arthropods, do not have a waxy waterproof outer layer on their cuticle and are thus very susceptible to drying out. In captivity, they need warm humid conditions. The substrate in their cage must be damp and provide places for hiding. If it is too damp, however, the water will plug the centipede's breathing spiracles and cause it distress. If you go to the woods, move aside a bit of leaf litter and stick your finger into the exposed black soil, that is about how damp the substrate in your terrarium should be.

The best substance to line a centipede cage with is a 50-50 mixture of sterilized potting soil and peat moss, which can be found at any garden store. Line the bottom of the tank with about four inches of this mixture, and cover it with a thin layer of leaf litter or terrarium moss. As it dries out, the substrate will need to be periodically misted again. It is best to heavily mist just a corner of the terrarium and mist the rest just enough to keep it damp, allowing the centipede to choose the moisture level it wants. If you begin to see fuzzy white patches that look like cotton, it is fungus and it means that you are spraying the tank too much and making it too damp, or that there is not enough airflow and venitilation.

Hiding Spots

Centipedes are nocturnal and hide during the day, emerging at night to hunt for food. Your centipede will need a secure place where it can sleep during the day. This shelter is also important for conserving water -- by pressing its body against the walls of a damp shelter, the centipede can help conserve body moisture.

A suitable shelter can be made by using aquarium silicone to cement a number of flat rocks together to form a shallow cave. An overturned piece of bark is also acceptable. The inside of the shelter should have just enough space for the centipede to curl up with its body touching all the walls at the same time. Mist the underside of the shelter occasionally to keep it damp inside.

The larger adult tropical centipedes are often secure enough that they will spend a large amount of time outside of their hiding spot, and may spend the day coiled up asleep in a corner of the tank.

Heating

The large scolopendromorphs found in the pet trade are all tropical or desert animals and need warm conditions. Daytime temperatures of 80-82 degrees are suitable. Since this is much warmer than conditions found inside most homes, some source of supplemental heat will probably be needed for the centipede.

Some keepers use an incandescent light bulb, placed outside the screen lid and focused insdie the tank, to warm the interior of the cage. There are several potential problems with this method, however. It tends to dry the cage out rapidly, which can be lethal for moisture-loving centipedes. The bright harsh lights also cause undue stress, since these animals prefer subdued lighting. If you plan to use a light bulb as a source of heat, you should use a red or blue bulb (centipedes cannot see these wavelengths and will act as if it were dark), and you will need to mist the cage often to keep the substrate damp. It should be noted that light bulbs cannot be used as a source of heat if your centipede is being housed in a plastic sweater box.

Another option for heating is the undertank heater commonly used for lizards and other small reptiles. These look like flat pads that stick onto the bottom of the cage and are heated electrically. The heat diffuses through the substrate to produce warm temperatures. They are the best method of heating a sweater box type of cage. The heater should be placed so it covers about one fourth of the bottom surface, at one end of the cage. Place shelters both at the warm end and at the cool side, so the centipede can move securely from warm to cool as it wishes.

Undertank heaters also present some safety problems, however. They tend to make the bottom of the substrate warmer and drier than the top, an unnatural condition. In the wild, centipedes escape from conditions that are too warm and dry by digging deeper into the soil. In a cage using an undertank heater, they will stick to this inborn behavior, even though in this situation burrowing more deeply actually exposes them to even more heat and dryness. You will need to mist the cage often to keep the top layer damp.

Light

Tropical centipedes are creatures of the rainforest floor, where they lurk among the leaf litter and debris. The thick canopy of leaves filters out most of the sunlight, and as a result the forest floor is a dim and unlit place even during the height of the day.

In captivity, centipedes prefer subdued lighting. Usually, the ambient light levels inside your house will be sufficient. No lighting is needed for the cage itself.

If you use an incandescent light bulb as a heat source, make sure it is colored blue or red. These wavelengths cannot be seen by centipedes, and they will act as if it were dark. This is also useful if you want to observe your centipede during its nocturnal activities.

Water

Your centipede should be provided with a large flat water dish for drinking. The evaporation of water from the dish will also help maintain the proper humidity level in the tank. Centipedes cannot swim, so you will need to fill the water dish with pebbles to prevent the centipede from falling in and drowning. Make sure the sides of the dish are low enough for the centipede to climb out easily.

Feeding a Centipede

Feeding a Centipede

Centipedes are active predators, which roam around at night looking for small arthropods, which they sieze and poison with their fangs. The prey is then chewed up with the powerful mouthparts and swallowed a small piece at a time. Salivary glands inside the mouth begin the process of digestion, and the food is passed on to a chamber inside the digestive tract known as the "gizzard" or "crop". Here, muscular actions break the food into tiny particles before passing it on to the three-chambered stomach and intestines, where the food is completely broken down. The resulting molecules of nutrient pass directly through the walls of the digestive tract and into the blood, where it is carried to all of the individual cells of the centipede's body. Waste products are filtered from the blood by a network of Malphigian tubes, which carry wastes to the posterior portion of the intestines. Here, the excess water is extracted and the remaining dry waste is excreted through the anus in the form of dry fecal pellets.

Most centipedes will accept only live food, since it is the movement and vibrations of the prey that allow the centipede to detect it (centipedes have very poor eyesight). Occasionally, a centipede may come across a dead prey item and recognize it by its scent, but many captive centipedes will refuse to eat prekilled food.

For the most part, centipedes will eat any small animal that they can overpower with their venomous fangs. Smaller centipedes can comfortably kill and devour prey such as mealworms, earthworms, small beetles, and small crickets. Adult tropical scolopendromorphs can handle waxworms, large beetles, crickets, pinkie mice and even small lizards or frogs. A fullgrown Peruvian or Vietnamese centipede is capable of killing and eating adult mice, but this practice should be avoided, as the sharp teeth of an adult mouse are capable of penetrating the exoskeleton of a centipede and causing fatal injury. Week-old mice that have not yet grown any fur, known as "pinkies", are not capable of biting and are a much safer food item for captive centipedes.

Centipedes can also be fed beetles, caterpillars, cockroaches and other insects that are captured outside. Be sure these are obtained from areas where they have not been exposed to pesticides.

Because of their low metabolic rate, centipedes do not require a large food intake. One or two crickets, mealworms or waxworms every three or four days is a sufficient intake for small centipedes. Larger adults can be fed one or two prey items a day. It is not unusual for a centipede to go several days without eating anything, only to "binge" and gulp down as many as ten prey items in a single day. Simply give the centipede as much to eat as it wants. If it is not hungry, it will not eat. If necessary, centipedes can go several weeks without food, but they should not be subjected to this stress.

It is important to keep the centipede's cage scrupulously clean, to avoid mite and fly infestations. Uneaten prey and the remains of meals should be removed as soon as possible to avoid attracting parasites.

Commonly-Kept Centipedes

Commonly-Kept Centipedes

Arizona centipede (Scolopendra heros) -- This species reaches a length of around seven inches and is the largest centipede found in North America. A desert animal, it ranges from northern Mexico to the southwestern United States, where it is found under rocks and logs where the humidity is locally high.

There are three distinct subspecies. The Arizona centipede, Scolopendra heros arizonensis, is the most common on dealer lists. It is tan in color with a black head and tail, and bright orange antennae. At first glance it is difficult to tell the head end from the tail, which most likely confuses predators and gives the centipede extra time to escape. The bluetailed centipede, S. h. heros, is yellowish in color with lighter legs and a blue or purple patch at the tail end. The third subspecies is S. h. castaneiceps, known as the redheaded centipede. It is brown or tan with yellow legs and a bright red head. All come from similar habitats and all can be cared for in the same way. All of these subspecies are also sold under the names "giant North American centipede" and "Sonoran desert centipede".

The bite is potent enough to kill frogs or mice. This species should not be handled.

Peruvian giant centipede (Scolopendra gigantea) -- One of the largest centipedes on earth, this monster reaches lengths of over a foot. Other similar species include S. viridicornis and S. crudelis (these may in fact turn out to be different names for the same centipede). It is sometimes sold as the Peruvian orange leg centipede or Peruvian yellow leg centipede. All of these are native to the rainforest floor of Brazil and Peru. The bite is very painful and should be considered potentially dangerous. Despite the painful bite and forbidding appearance, natives in South America roast these animals over a fire and eat them.

Vietnamese giant centipede (Scolopendra subspinipes) -- Another large tropical centipede that reaches lengths of almost a foot. It is found throughout southeast Asia and the Phillipines. In appearence, it is tan or amber in color with a darker head and tail. The bite should be considered medically significant, and this species has been blamed for at least one human death.

Garden centipede (Scolopocryptops sexspinosa) -- This one of the centipedes that are commonly found under rocks and logs in woods and gardens in the midwestern and eastern United States. Related species in the same genus include S. peregrinator, S. rubiginosa and S. gracilis. Despite their small size (about two inches in length), these reddish-orange or greenish scolopendromorphs are faithful replicas of their larger tropical cousins, and prowl the leaf litter hunting for small arthropods. The bite is painful but not threatening, and the garden centipedes can be kept in the same warm and damp conditions as their larger relatives.

House centipede (Scutigera coleoptrata) -- Although not found on dealer lists, this centipede is relatively common inside houses, where it hides in warm dark places by day and emerges at night to feed on flies and other small prey animals. It is sometimes found by human occupants when it falls into a sink or bathtub and cannot climb out. A member of the scutigeromorph group, the house centipede differs drastically in appearence from the larger scolopendromorphs found in pet shops. The legs are long and thin, while the body is more rounded than most centipedes. It can be kept in much the same conditions as the smaller scolopendromorphs.

Other species of Scolopendra are also sometimes available from time to time, identified largely by their locale. Some of the varieties which appear are the Vietnamese purple centipede, Florida Keys centipede, West Indies orange centipede, and the South African rainbow centipede. All are cared for in the same manner.

Centipede Evolution

Centipede Evolution

Centipedes have a very sparse fossil record, since they are delicate and easily destroyed after death, and they live in habitats which only rarely produce fossils.

The arthropods, the group to which centipedes belong, are evolutionary descendents of the very ancient segmented worms known as the Annelida. These animals were constructed in a series of rings or segments, each externally identical to those before and after it, with a mouth at one end and an anal opening at the other. Each segment contained a number of sensory bristles or hairs. The annelids are one of the earliest of the multicellular organisms, and fossil traces of these animals date all the way back to pre-cambrian times, over half a billion years ago. The earliest segmented worms lived with such other ancient animals as jellyfish and sponges. Modern annelids include the common earthworm or nightcrawler, known by the scientific name Lumbricus terrestris.

One group of annelids underwent a process of evolution which resulted in the birth of the arthropods. Each body segment developed a pair of walking legs. The first six segments of the annelid ancestor were fused together to produce a head, which contained a number of simple eyes. The appendages in these fused segments were modified to form mouthparts. Although the earliest arthropods were marine animals, two separate groups left the sea between 450 and 420 million years ago, to become the ancestors of today's myriapods and scorpions.

One branch of these early arthropods are known as uniramians, which are distinguished by having only one branch for each leg. Modern descendents of the uniramians include the centipedes, millipedes, and the insects. The earliest known fossil myriapod consists of a number of scutigeromoprh legs from the late Silurian period, approximately 400 million years ago. Some earlier fossils may represent burrows formed by early myriapods. The earliest recognizable centipedes appear in the Devonian and Carboniferous period. It is a virtual certainty that centipedelike organisms were one of the first terrestrial animals, and that earlier specimens of fossil centipedes will be found as the fossil record becomes more complete.

The scutigeromorphs and the lithobiomorphs have many anatomical traits in common. Both have 15 pairs of legs, and both add new segments to their body length as they get older. It is probable that these two orders diverged from each other only recently in evolutionary terms.

There are almost 3,000 species of centipedes living on earth today. It is estimated that about 6,000 species remain to be described by science.

Centipede Anatomy

Centipede Anatomy

Exoskeleton

Centipedes, like all arthropods, lack internal skeletons. Instead, they are covered with a hard exoskeleton made of cuticle, which protects the soft internal organs and also serves as an attachment point for the centipede's muscles. Most of the cuticle consists of chitin, which is the same substance found in crab shells.

The arthropod cuticle is constructed in several layers. The inner layer is made up of the epidermis. The cells of the epidermis are alive and secrete the chitin which makes up the outer shell.

Centipedes differ from most arthropods in lacking a waxy outer cuticle. This leaves them vulnerable to water loss and desiccation. Centipedes are thus limited to living in areas with a locally high humidity, such as under rocks or logs. Even in desert areas, centipedes are never found far from moist areas. Centipedes characteristically rest in damp areas that afford them maximum contact with their body surface, a tactic that allows them to conserve moisture. Failure to provide proper humidity and moisture will kill them, and more captive centipedes probably die from being kept in improperly dry conditions than from any other cause.

Like all arthropods, the exoskeleton of a centipede is dead and cannot grow. As the centipede gets larger throughout its life, its cuticle layer becomes tighter and tighter. Periodically, if the centipede is to continue growing, it must shed its exoskeleton and replace it, a process known as ecdysis or molting. When the centipede is ready to molt, a new cuticle layer will grow underneath the old one. During this time, the centipede will stop eating and will retreat to a dark sheltered area for protection. Just before the molt, a thin layer of fluid will form between the old exoskeleton and the new one, loosening it. Using fluid pressure to swell up its body, the centipede splits the old exoskeleton open between the first and second tergites, and climbs out, pulling each leg from its old shell and compressing the old skin like an accordion. The shed skin is a precise replica of the centipede---all of the legs, mouthparts and even the lining of the genital openings -- are shed in one piece. Once the shed is complete, the centipede will remain still for a short time while the new exoskeleton expands, dries and hardens. After this process is finished, the centipede will usually eat the shed exoskeleton.

Young centipedes which are growing rapidly will shed more often than adults who have reached maturity.

Segments

A centipede's body is divided into a series of segments, each of which is virtually identical to the one before it. The first six segments are fused together to form the head, and the mouthparts are formed from the modified legs that once belonged to those segments. In the scolopendromorphs, each body segment contains a pair of walking legs, one on each side. The number of body segments is the same as the number of pairs of walking legs.

The segments are flattened horizontally, giving the centipede a ribbonlike appearence. This allows the animal to wedge itself under rocks and logs in search of prey, and also to spend the day in tightly enclosed areas with locally high humidity. Each segment is protected on the top by a hard plate called a tergite, and another hard plate below, called a sternite. The tergites and sternites are held together by a flexible pleural membrane.

Legs

The number of legs in centipedes ranges from 15 or so to over 150, but all of the scolopendromorphs have either 21 or 23 pairs. Each pair of legs is connected to the ones near it by a band of pliable connective tissue, which helps insure that the legs will not become entangled with each other. In most species, each pair of legs is a little bit longer than the pair immediately in front of it. The legs on each segment move opposite to each other--the leg on one side moving forward while the leg on the opposite side is moving backwards. Some centipedes are capable of running at speeds of almost two feet per second.

Most species of centipede have only one claw at the tip of their feet, and run and walk on tiptoe. The house centipede has a lengthened and flattened foot, which allows it to run faster than most species.

Several species of centipede are capable of dropping some of their legs when threatened by a predator, a tactic known as "autotomy". The detached legs continue to move and thus distract the predator's attention while the centipede escapes. A few species can rub their last pair of legs together to produce a warning noise. Some others can use their rear legs as pincers to deliver painful strikes to attackers.

Legs that are lost can be regenerated and replaced at the next molt.

Trachea

Centipedes breathe through a series of tracheal tubes, in a manner somewhat similar to that used by insects. Each segment of the centipede's body has a network of finely branching tracheal tubes inside it, which carries air inside and allows oxygen to diffuse directly to the body tissues. The tracheal tubes exit the body through a hole known as the spiracle, located on the side of the body segment in the pleural membrane, near the base of the legs. In some groups, each body segment contains spiracles. In the larger scolopendromorphs, spiracles are found on segments 4, 6, 8, 11, 13, 15, 17, 19, and 21. Unlike the insects, centipedes are not capable of closing their spiracles, and these openings are a major source of moisture loss for the animal.

In some species of house centipedes, tracheal tubes surround the heart in a dense network, allowing some oxygen to diffuse directly into the blood before it is pumped throughout the body. In other centipedes, the blood carries only nutrients and does not transport oxygen to the body cells.

Breathing doesn't require any muscular action on the part of the centipede. Instead, the air flows directly through the trachea into the body tissues, where gas exchange takes place. Since air cannot diffuse very far, the distance between the interior of the body and the tracheal opening cannot be very far--the long thin body shape of the centipede is adapted to allow the maximum amount of oxygen to diffuse into tissues as efficiently as possible.

Because this respiratory system is rather inefficient, however, the body tissues cannot be rapidly and consistently supplied with oxygen. When the centipede is very active and using up energy, such as when running away from a predator, the oxygen reserves are used up quickly and cannot be rapidly replaced. Thus, centipedes are capable of only short bursts of intense activity before they tire, and must stop and rest for a time to reoxygenate their body tissues.

Heart

The centipede's heart is a long hollow tube that runs along the length of the back, just beneath the cuticle. Like most arthropods, the centipede has an "open" circulatory system, in which the blood is not confined to vessels. Instead, it fills the entire body cavity and covers and surrounds all of the internal organs. Contractions of the heart cause the blood to swish around inside the body cavity, moving nutrients from one end to the other and carrying wastes away from the body cells.

A cut or opening in the body wall is a serious matter for a centipede, since it may allow a significant amount of blood to pour out of the body before the clotting agents can stop it, causing the centipede to bleed to death.

Eyes

All of us are familiar with the large multifaceted eyes of insects such as houseflies and dragonflies. These large compound eyes are actually a gathering of many hundred smaller units, each with its own lens and optic nerve. The image formed by these eyes consists of a "mosaic", a gathering of multicolored dots that forms a color image. The larger the number of facets in the compound eye, the more sharp the image that is formed will be. Visual hunters like dragonflies can have several thousand facets in their compound eyes, giving them very sharp images and excellent vision.

Centipedes differ from insects in having only simple eyes, not compound. The simple eyes, known as occeli, are clustered in two groups on the head, however, making them appear as if they are compound eyes. In simple eyes, there is only one lens structure, and the image is not as clear or sharp, nor is it as sensitive to movement. Their poor vision does not present many problems for the centipede, however, as nearly all are nocturnal and are active during the night, where they are far more dependent on sensing vibrations and air currents than on visual cues. Many centipedes, including all of the geophilomorphs, do not have eyes at all and are completely blind. The scutigeromorphs, by contrast, have large clumps of occeli called "Pseudocompound eyes", which form good images and allow these animals to hunt their prey visually, unlike most centipedes.

Centipedes receive most of the information they get about their surroundings from their antennae, which are used for sensing chemical information, rather than their eyes.

Fangs

All centipedes are predators. The first body segment contains a pair of clawlike appendages called maxillipeds, consisting of a modified pair of legs which are connected to venom glands inside the body. The sharp tips of the claws are used to penetrate the exoskeleton of a prey insect, and muscles in the centipede's body squeeze the venom glands to force poison through the hollow fangs into the victim's body. These claws can be used to kill prey ranging in size from insects and other arthropods to small vertebrates such as rodents or lizards. Although the venom is not particularly powerful in most species, punctures from a poison claw can be painful to humans, and some of the larger tropical centipedes can produce systemic effects and are potentially dangerous. There is one report in the literature of the death of a seven year old girl from the bite of a large tropical centipede in the Phillipine Islands (probably the species S. subspinipes).

Repugnatory Glands

Some centipedes have a series of glands running along the body known as repugnatory glands. These are defensive in nature. If threatened, the centipede can secrete a noxious chemical from these glands, which then runs down the legs. It has been reported that, when some centipedes are handled, the sharp claws on the feet can puncture the skin of the handler and allow the secretions from the repugnatory glands to enter, causing a trail of inflamed and painful eruptions. The scolopendromorph centipedes are believed to lack repugnatory glands.

Breeding Millipedes

Breeding Millipedes

The sexual organs of a millipede are located in the thoracic segments, which are made up by the first three segments behind the head. These three segments have only one pair of legs on each, but in mature males the third segment behind the head also has an additional pair of sexual organs called gonopods, which look something like legs. The male testes secrete sperm into a hard packet called a spermatophore. The females receive this spermatophore and store it in a chamber called a spermathecae. Live sperm can be stored in the spermathecae for a considerable period of time, and female millipedes may lay fertile eggs up to a year after they have mated. It is not unusual for wildcaught females to produce young after a few months in captivity, even though they have not been housed with a male.

In some species of millipedes, adult males may undergo a transition known as "periodomorphosis", in which a sexually mature male molts and emerges as an immature male with undeveloped sex organs. He later molts again and re-emerges as a sexually mature male once again. It is not known why this process takes place. It may be a response to adverse environmental conditions, helping the millipede conserve energy during lean times. Or it may be a mechanism to corrrect a temporary imbalance in the ratio between mature males and females, insuring that the leftover males get a chance to mate later.

A few species of millipedes, including Polyxenus lagurus and Proteroiulus fuscus, are parthenogenic, which means that adult females are capable of laying fertile eggs without havig mated with a male. In these species, the eggs hatch directly into females, and no males exist.

The mating process varies between species. In some millipedes, the male simply deposits a spermatophore on the ground and leaves it for the female to find later. She picks up the spermatophore and inserts it into her spermathecae. In other species, the male and female pair will coil around each other so their sex organs meet, and the male will use the legs on his tenth segment to place the spermatophore inside the female.

The eggs are laid in a small dung-filled chamber which is excavated into the ground. Upon hatching, the young millipedes have only six body segments and three pairs of legs on the thoracic segments. They are very small and white, and look very much like beetle grubs. They tend to spend most of their time feeding, and can often be found congregated on top of their food or burrowing into it. Since they are so tiny at this point, they can be easily overlooked, and many a millipede keeper has accidentally thrown away a number of young when removing rotten food from the tank. If you suspect that your millipede may produce young, make sure you carefully inspect any used food before you remove it.

As they grow and molt, they add body segments. At this point in time, they will prefer to spend much much of their time curled up in a tiny excavated chamber in the soil, which is usually constructed under an object such as a rock, piece of wood, or their food dish. They are usually a light grey color, and get darker with each successive molt. Young millipedes grow slowly, and do not reach breeding size for two or three years. The adults can live a further three or four years. Adult millipedes continue to grow and molt even after they have reached sexual maturity.

Handling Millipedes

Handling Millipedes

Millipedes are quite amenable to handling. With a few precautions, they can be safely and confidently handled by even small children, since they do not move fast, do not bite, and have tough exoskeletons that can stand a fair amount of abuse.

The safest way to pick up a millipede is to place your hand flat in front of it, palm up, and allow it to walk from the substrate onto your hand. You will feel it gripping your skin with the claws on its legs as it moves along.

Larger millipedes can be carefully picked up by grasping the cuticle between thumb and forefinger and lifting it straight up. The millipede may try to hang on to the substrate with its claws, so be careful you do not injure it or pull off any legs.

When first handled, the millipede may curl up into its defensive "watchspring" position. Some of the large millipedes also have the habit of defecating when first picked up. Once the millipede feels safe, it will uncurl from its defensive posture and begin exploring your hand, tapping your skin with its antennae as it walks along. By successively placing one palm in front of the other, your pet can be encouraged to walk along until it gets tired and stops for a rest.

There are some safety precautions that must be kept in mind. Although millipedes do not bite, they are capable of excreting irratating fluids from their metathoracic glands if they are frightened or handled too roughly. This fluid is harmless in most species, but it can cause some pain and irritation if it gets into an open cut, or if it is accidentally rubbed into the eyes or nose. It is important to make sure to always wash your hands with soap and water after handling any millipede. This is particularly important with young children, who often get excited and goad the millipede into secreting its defensive fluids.

Some species of millipede have stronger secretions, and can cause some pain and blistering on exposed skin. These species should be handled with care to avoid provoking them into a defensive reaction.

There are also some safety precautions that must be applied to the millipede. Although they are capable of a strong grip using their myrads of claws, accidental falls can still happen. Falls from a height are capable of breaking open the millipede's exoskeleton, causing it to rapidly bleed to death. Handle your millipede with care. Avoid any sudden movements which may frighten your millipede and cause it to curl up and drop off your hand. Do not let it walk upside down on your hand or arm, as it can easily lose its grip and fall. It is best to always hold your millipede no more than six inches over a table or the floor, so it will not be injured if it accidentally falls.

Young millipedes are very delicate and easily injured. They should not be handled.

Feeding Millipedes

Feeding Millipedes

Millipedes feed largely on dead and decaying plant material. They are among the most efficient decomposers in the forest ecosystem, and convert a prodigious amount of leaf litter into organic material that serves to replenish the soil and fertilize the forest growth. In its lifetime, an adult millipede will have eaten at least five times its own weight in leaf litter and decaying vegetation. In the sheer volume of plant material that they convert into usable organic fertilizer, the millipedes are surpassed only by the earthworms.

To help them break down the plant materials they eat, millipedes have commensual protozoans and bacteria living in their digestive tract. These microbes are capable of breaking down the cellulose found in plant tissues and converting them to sugars, which can then be digested and metabolized by the millipede. Hatchling millipedes do not have any protozoans living in their intestines; they obtain them by finding and eating the fecal droppings of their older relatives, a practice known as "coprophagy". These partially-digested droppings also provide a ready source of soft food for the young millipedes. Adult millipedes will also sometimes eat their own droppings, in order to pass them through the digestive tract again and extract all of the partially-digested material that was missed the first time.

The jaws and mouthparts of even the largest millipedes are very weak, and they are not capable of chewing tough plant material. Even the skin of an apple is an impenetrable barrier to them. In the wild, they feed mostly on vegetation that has already partially rotted, softening it enough for the millipede to handle. In captivity, therefore, they need to be fed soft mushy plant material such as over-ripe melon, banana and mushroom. They will also eat fruits and vegetables such as squash and apple, and green leafy vegetables such as kale and leaf lettuce, provided these are cut into slices and allowed to partially rot and soften before being offered as food.

Millipedes should be fed every day, and offered as much food as they will consume in a night. They eat a large amount for their size, and excrete almost constantly (the excreta looks like a little round pellet). An adult African giant millipede can easily consume a piece of melon, a slice of squash and a shred of kale, each the size of a fifty-cent piece, in a night. Iceberg lettuce should be avoided as a staple, as it contains mostly cellulose and water and has very few nutrients. A varied diet consisting of melons, fruits and leafy greens is best.

Millipedes also need a source of calcium to strengthen their exoskeletons. This can be provided by placing a small piece of chalk or clamshell in their tank. Another option is to sprinkle a tiny pinch of calcium powder on their food once a week.

Housing Millipedes

Housing Millipedes

Millipedes are not as active as the faster centipedes and do not require as much room. A two-and-a-half or five gallon glass aquarium provides adequate space for even the largest of the giant millipedes. As a rough rule of thumb, you will want a tank that is at least as wide as your millipede is long, and at least one and a half times as long as the length of the millipede

Millipedes are not capable of climbing up glass or smooth plastic, but they are capable of using the claws on their feet to grip the bead of silicone glue inside the corners of the tank, and climb up and out. Your millipede cage will need a securely locking lid. The commercial fluourescent hoods that are used with fish tanks are not suitable for a millipede tank. Millipedes are much stronger than they appear, and are capable of wedging their heads underneath even the heaviest lids and leveraging it open enough to slip through.

The best kind of lid for a millipede tank is a screen mesh lid with metal clips to hold it on tightly, often sold for keeping reptiles and small mammals. Make sure the wire mesh is tight enough to prevent the millipede from squeezing through the holes. Note that the sharp wires used in these cages do present a potential danger to the millipede, which can sometimes cut its exoskeleton on these wires and bleed to death. Another type of aquarium top, also used for reptiles and rodents, consists of a perforated metal sheet with two rotating latches at either end. These latches hook underneath the lip that runs around the top of the aquarium to hold it on. This type of screen lid is less suitable for keeping millipedes---the metal is too flexible in the middle and a determined millipede, if it is able to reach the lid, will be able to wedge its head between the lid and the aquarium rim and escape.

The best option for housing a pet millipede is one of the clear plastic sweater boxes that can be found in any department store. These come in a variety of different sizes, and all have their own lids that snap on securely. They are also lightweight and take up a bit less room than an aquarium. Another advantage of the sweater boxes, particularly if you will be keeping a number of invertebrate pets, is that they can be securely stacked atop one another to put a large number of cages in the smallest possible area. One disadvantage of the sweater box, however, is that the plastic isn't as clear as glass, which may make your pet difficult to see.

Sweater boxes must be modified a bit before they make a suitable home for your millipede. Millipedes cannot tolerate damp stagnant air, so you will need to drill a large number of airholes for ventilation, along the top and bottom edges all around the box. This can be done with a hand drill, or the holes can be carefully melted through with a heated screwdriver or soldering tool. The holes should be no larger than half the body width of the millipede, to prevent escapes. If your millipede cage does not have adequate ventiliation, the warm damp conditions will encourage mold and fungus growth that will ruin the cage and present a danger to your millipede. Also, if the humidity level is too high, it will interfere with the diffusion of air into the trachea.

The final option for housing your millipede is one of the plastic "critter cages" that can be found in pet stores. These are available in a variety of sizes. Make sure you get a model that has little latches to hold the lid on securely---the cheaper versions have flimsy snap-on lids that often come apart whenever the cage is picked up by the handle. Millipedes are inoffensive scavengers and do not present any danger to each other. They will live happily together, in the same tank, in small colonies consisting of six or seven individuals. Provide the colony with a tank of at least ten gallons capacity so each has room to wander around and establish its own hiding place. Baby millipedes can be safely kept in the same enclosure as their older relatives.

Although different species of millipedes will not bother each other and can be kept in the same tank, there are some cautions that need to be considered. Millipedes from different geographic areas may have slightly differnet habitat preferences, and it may be difficult to provide optimal conditions for all of them in the same tank. In addition, animals from one area may have been exposed to pathogens or internal parasites that the others have not been, and have no natural immunity to. It is remotely possible that one of your millipedes may introduce a health problem that will wipe out the others. To play it safe, it may be best not to mix different species together in the same tank.

Substrate

Millipedes dry out very easily, and require damp and warm conditions. The substrate in their cage must be kept slightly moist. If you go to the woods, move aside a bit of leaf litter and stick your finger into the exposed black soil, that is about how damp the substrate in your terrarium should be.

The most practical and useful substrate for a millipede tank is a 50-50 mixture of sterilized potting soil and peat moss, which can be found at any garden store. Line the bottom of the tank with about four inches of this mixture, and cover it with a thin layer of leaf litter or terrarium moss. Millipedes are inveterate burrowers, and this substrate will soon be criss-crossed with a network of tunnels and chambers. Very young millipedes in particular spend almost all of their time underground, where they avoid predators while they are eating and growing.

Cover the top of the soil/peat moss substrate with a very thin later of bark chips or leaf litter to help keep it damp. As it dries out, the top of this substrate will need to be periodically misted again. It is best to heavily mist just a corner of the terrarium and mist the rest just enough to keep it damp, allowing the millipede to choose the moisture level it wants. If you begin to see fuzzy white patches that look like cotton, it is fungus and it means that you are spraying the tank too much and making it too damp, or that there is not enough airflow and ventilation.

Over time, a deep layer of feces will build up in your millipede tank. This will decompose and form a crumbly black humus. This layer of rotted feces may sound unappealing, but it does not normally present any odor problems. Since young millipedes are coprophagous, the substrate in any tank that contains babies should not be changed. Even in tanks that house single millipedes and do not have any young, it is not necessary to change the substrate so long as it is kept free of fungus, mites and other pests.

Hiding Spots

Millipedes are nocturnal and hide during the day, emerging at night to forage for rotting vegetation and plant material. Your millipede will need a secure place where it can sleep during the day. This shelter is also important for conserving water: by pressing its body against the walls of a damp shelter, the millipede reduces the amount of water vapor it loses through evaporation, and thus conserves its body moisture.

A suitable shelter can be made by using aquarium silicone to cement a number of flat rocks together to form a shallow cave. An overturned piece of bark is also acceptable. The inside of the shelter should have just enough space for the millipede to curl up with its body touching all the walls at the same time. Mist the underside of the shelter occasionally to keep it damp inside.

Heating

Millipedes inhabit cool damp forest floors and do not need as high a temperature as some of the other triopical arthropods. Temperate North American species of millipedes, such as Narceus, can be kept at ordinary room temperatures and do not require any supplemental heat.

The larger tropical millipedes found in the pet trade need somewhat warmer conditions. Daytime temperatures of 80-82 degrees are suitable, as long as the millipede has a damp hiding spot to spend the day.

Some keepers use an incandescent light bulb, placed outside the screen lid and focused insdie the tank, to warm the interior of the cage. There are potential problems with this method, however. It tends to dry the cage out rapidly, which can be lethal for moisture-loving millipedes.

Another option for heating is the undertank heater commonly used for lizards and other small reptiles. These look like flat pads that stick onto the bottom of the cage and are heated electrically. The heat diffuses through the substrate to produce warm temperatures. They are the best method of heating a sweater box type of cage. The heater should be placed so it covers about one fourth of the bottom surface, at one end of the cage. Place shelters both at the warm end and at the cool side, so the millipede can move securely from warm to cool as it wishes.

Undertank heaters also present some safety problems, however. They tend to make the bottom of the substrate warmer and drier than the top, an unnatural condition. In the wild, millipedes escape from conditions that are too warm and dry by digging deeper into the soil. In a cage using an undertank heater, they will stick to this inborn behavior, even though in this situation burrowing more deeply actually exposes them to even more heat and dryness. You will need to mist the cage often to keep the substrate damp.

Light

Tropical millipedes are creatures of the rainforest floor, where they lurk among the leaf litter and debris. The thick canopy of leaves filters out most of the sunlight, and as a result the forest floor is a dim and unlit place even during the height of the day.

In captivity, millipedes prefer subdued lighting. Usually, the ambient light levels inside your house will be sufficient. No lighting is needed for the cage itself.

If you use an incandescent light bulb as a heat source, make sure it is colored blue or red. These wavelengths cannot be seen by millipedes, and they will act as if it were dark. This is also useful if you want to observe your millipede during its nocturnal activities.

Water

Your millipede should be provided with a large flat water dish for drinking. The evaporation of water from the dish will also help maintain the proper humidity level in the tank. Millipedes cannot swim, so you will need to fill the water dish with pebbles to prevent the millipede from falling in and drowning. Make sure the sides of the dish are low enough for the millipede to climb out easily.

Commonly-Kept Millipedes

Commonly-Kept Millipedes

North American millipede (Narceus americanus) -- This very common millipede is found in damp woodlands throughout the eastern part of the United States. It is dark reddish brown in color, with narrow red bands at the margins of each segment. The total length is around four inches.

African giant millipede (Archispirostreptus sp) -- This is a general name for a number of large black millipedes from various areas of Africa. Many times, these animals cannot even be identified in the proper genus---many of the "African millipedes" found in pet shops may be members of the genus Spirostreptus. Nevertheless, these huge diplopods are readily available in the pet trade. They can reach lengths of over a foot, and can be as much as an inch in diameter. Despite the forbidding appearance, all of them are completely harmless and relatively easy to care for.

Fire Millipede (Aphistogoniulus sp) -- This brightly colored millipede is found in Madagascar. They are bright red with black stripes, and reach a total length of around four inches. Fire millipedes inhabit the damp floor of the Madagascar rainforests.

Desert millipede (Orthoporus sp) -- A general name for a number of large often brightly colored millipedes from the American southwest. They range in size from four to six inches, and vary in color from a dark brown to a light tan or orange, and are sometimes sold under the names "Sonoran desert millipede" or "giant North American millipede". Although they are found in dry desert areas, they live exclusively in damp humid microhabitats, and can be kept in the same captive conditions as other millipedes.

Yellow Spotted Millipede (Harpaphe haydeniana) -- Another brightly colored millipede, from the Pacific Northwest in the United States. It reaches about three inches in length. As the name suggests, this species is glossy black with a series of vivid yellow spots along the sides. The bold colors are a warning, for this millipede can defend itself with a puff of hydrogen cyanide that can poison a potential insectivore predator (although the amount of cyanide produced is not enough to affect a human). It is not known how the millipede prevents itself from being poisoned by its own defensive cloud.

Millipede Evolution

Millipede Evolution

Millipedes live in habitats such as moist forest floors where fossilization is very difficult. As a result, the fossil record for these animals is very sparse, and not much is known of their early history.

Some fossil burrows from the Ordovician, about 400 million years ago, may have been made by millipedelike creatures. The oldest definite fossil millipedes, known as Kampecaris tuberculata, have been found in Scotland, dating back to the upper Silurian period. Some excellent fossil millipedes have been found in Illinois, dating back to the Pennsylvanian period. One of these, Euphoberia, measured almost a foot in length. Today, there are around 7,000 species of millipedes that have been named by scientists, and it has been estimated that there are probably ten times that number that have not yet been scientifically described.

Millipede Anatomy

Millipede Anatomy

Exoskeleton

Like all arthropods, millipedes lack an internal skeleton, and instead are protected by a tough outer shell called an exoskeleton or cuticle, made of several layers. The inner layer is made up of the epidermis. The cells of the epidermis are alive and secrete the chitin which makes up the outer shell. The middle layer of the exoskeleton is made up of soft, flexible chitin which provides an elasticity, allowing the millipede to absorb impacts. The outer layer is also made of chitin, but it has been stiffened and hardened by the addition of calcium carbonate crystals--the same substance that makes up clamshells -- to form a durable exterior. Millipede exoskeletons are so tough that they can support up to 25,000 times the millipede's own weight before being crushed.

The exoskeleton is dead and cannot grow. As the millipede gets larger, it must periodically shed its skin and grow a new one. When the old exoskeleton gets too tight, the millipede will secrete a new one underneath it. It will then split the old cuticle open and pull itself out, carefully extracting all of the legs, antennae and mouthparts. The newly emerged cuticle is soft and flexible, and takes several hours to dry and harden. During this stage the millipede is extremely vulnerable to predators, and it will usually seek out a secure hiding spot to carry out the molting process. Some species dig themselves a special molting chamber in the soil.

After the new exoskeleton has completely hardened, the millipede will usually eat the old cuticle to recycle the nutrients and calcium it contains. The large millipedes found in the pet trade often have tiny light-colored mites living on their exoskeletons. These do not appear to cause any harm, and it is generally believed that they help the millipede by eating and removing wastes and detritus that cling to the exoskeleton.

Segments

Like centipedes, the millipede's body is divided into a long series of segments, each more or less identical to the one before it. Each segment is actually formed by the fusion of two sections during embryonic development, and thus each millipede segment has two pairs of legs, as well as armored plates above (known as tergites) and below (known as sternites). The tergites and sternites are held together by a tough flexible pleural membrane.

Each segment also contains a spiracle, four on each segment in the sternite near the leg bases, through which the millipede breathes. Millipedes do not have lungs and do not breathe through their mouth like vertebrates. Instead, air is carried directly into the body through a finely branching system of tubes known as trachea, and these open to the outside through the spiracles. The fine network of trachea allows oxygen to diffuse directly into the body tissues and carbon dioxide to diffuse out through the spiracles. This arrangement is inefficient, and because millipedes cannot oxygenate their body tissues rapidly they tire very easily, but this is not a disadvantage since they move slowly all the time anyway, and depend on their protective cuticle and metathoracic glands for defense rather than speed.

Young millipedes typically have far fewer segments than adults of the same species (most species have six segments and three pairs of legs when they hatch). With each successive molt, three or four new segments are added until the young millipede reaches adult size. Large "giant millipedes" may have over 100 body segments as adults.

Legs

Although a millipede may have as many as 400 legs, they are not built for speed. The legs are very short and have a limited mobility. Rather than being predatory sprinters like centipedes, millipedes are designed for pushing their way through soil and leaf litter in search of rotting vegetation and other sources of food.

Most of the segments on the millipede's body have two pairs of legs. The only exceptions are the three segments immediately behind the head, known collectively as the millipede's "thorax". These have only one pair of legs each, but they contain the millipede's sexual organs. In males, the rear segment of the thoracic region contains a pair of sexual organs, which are used to transfer sperm from the testes to a small gelatinous packet called a spermatophore. During breeding, this packet is transferred to a pair of highly modified legs on the male's seventh body segment, called gonopods, which are then used to place the spermatophore into the female's genital opening.

During walking, each pair of legs on a segment is lifted at the same time. The pairs move oppositely to each other -- the pair of legs on the left side moving forward while those on the right side move backward. The millipede walks by using successive waves of motion along its body. You will easily be able to see this "rippling" action as the millipede moves along.

Eyes

Millipedes do not have the large compound eyes found in insects. Instead, they have "simple" eyes, known scientifically as ocelli, that can sense light and dark but are not very good at forming images. As a result, the eyesight of millipedes is very poor, and they are practically blind. Since nearly all millipedes are nocturnal, though, lack of good vision is not a problem for them. They get most of their information concerning their surroundings from their antennae, which are loaded with chemical sensors. Millipedes are also very sensitive to vibrations that they pick up through the ground.

Metathoracic glands

Most species of millipede have a number of glands running along the sides of the body which produce noxious chemicals to drive away predators. In some species, these metathoracic glands produce a tiny cloud of hydrogen cyanide gas, which to humans has a pleasant almond odor, but which has a deterring (and potentially lethal) effect on such millipede predators as beetles and shrews. In other species, the chemical arsenal may include quinones, hydrochloric acid, aldehydes, toluquinone, benzaldehyde or benzoquinones. These chemical secretions are usually harmless to humans, although some millipedes can produce a blue or purple stain on human skin. Millipedes of the genera Rhinocricus and Spirostreptus, however, release stronger chemicals that can produce blisters on some people. The secretions of most millipede metathoracic glands can cause painful burning and itching if they get into the eyes, nose or an open cut.

In addition to their metathoracic glands, a few millipedes produce chemicals in their cuticle that glow in the dark, a phenomenon known as "bioluminescence". In the United States, the genus Motyxia, which is found in California, is bioluminescent. Since millipedes are virtually blind and have no use for light while they are active, it is assumed that this glow serves as an anti-predator mechanism, perhaps giving a visual warning that the millipede, with its chemical arsenal, is distasteful to predators.

Centipedes

Centipedes

Centipedes, despite their resemblance to millipedes, are not very closely related, and are placed in a separate class within the arthropods known as Chilopoda, from the Greek words for "jaw feet". This is a reference to the venomous fangs, which are actually formed from modified legs. The centipedes are some of the oldest terrestrial animals on earth, and some of the very first creatures to crawl from the sea onto the land were probably very similar in appearence to modern centipedes.

All of the centipedes are nocturnal predators which live by actively hunting down insects and other small prey animals. They are found mostly in tropical forest areas, but have also established themselves in temperate forests and desert areas. Although popularly referred to as "hundred-leggers", most centipedes have between 15 and 30 pairs of legs, one pair on each body segment.

There are four orders of centipedes within the class Chilopoda. One of these is the Lithiobiomorpha, known as stone centipedes. Small and secretive, they live under rocks and in leaf litter and are not often seen. The snail centipedes, of the order Geophilomorpha, are small yellow animals that live in rotting logs and soil. The centipedes most often seen by people in the United States are the house centipedes, of the order Scutigeromorpha. They are of small size and have long thin legs. Most of these are found in southern Europe and the Middle East -- in the United States, they cannot survive outdoors and instead live in people's houses. The largest of the chilopods are the tropical centipedes in the order Scolopendromorpha. Found in warm and damp areas of the world, the tropical centipedes are several inches long, with the largest species approaching one foot in length.

Almost all of the "pedes" available in the pet trade are from the order Scolopendromorpha. These are large arthropods, averaging five or six inches in length and either 21 or 23 pairs of legs. The largest members of the group can reach lengths of twelve inches. The scolopendromorphs are fast-moving and aggressive, and can inflict painful wounds. All are predators which attack their prey with venomous fangs, and in some species the venom is powerful enough to kill small vertebrates. Although there are has only been one reported case of a human death resulting from a centipede, they can deliver painful bites and should not be handled.

Some of the larger scolopendromorph centipedes have lifespans of over ten years.

Keeping and Raising Millipedes and Centipedes

Keeping and Raising Millipedes and Centipedes

Invertebrates rule the earth. Despite the attention given to the backboned vertebrates--the fish, amphibians, reptiles, birds and mammals-- it is the invertebrates, animals without backbones, which have always dominated life on our planet. Invertebrate animals have flourished in every possible ecological niche, from the deepest depths of the oceans to the thinnest mountain air, from sweltering deserts to steaming jungles to freezing polar regions. Of the 26 major groups of animals, known as "phyla", all but one consists solely of invertebrates. Of all the animals known to science, over 99% are species without backbones.

Today, invertebrates such as tarantulas, scorpions, millipedes and centipedes are the fastest-growing sector of the exotic pet trade. A wide variety of species are now inexpensively available from breeders, dealers and pet shops. So if you are looking for a fascinating pet that is unusual, easy to care for, doesn't take up much room, and doesn't require much maintenance, perhaps one of the several invertebrate species is for you.

This book provides biological information and care requirements for two commonly-kept varieties of invertebrates -- centipedes and millipedes. These animals require only the most simple of accomodations and the most minimal of care. Once rare in captivity, they are now becoming more readily available, and the number of people keeping these unusual animals continues to grow rapidly.

Although these animals have many husbandry needs in common and there will thus be some overlap between sections, each section of this book is designed as an independent unit. If you are keeping only one variety of these animals, you will find all the care information you need in that particular section.

All living things are classified by biologists into a hierarchical system of categories, sorted according to their biological characteristics (their "morphology") and their evolutionary history (their "phylogeny"). This science of classification is known as "taxonomy".

The basic unit of taxonomy is the species, which is biologically defined as "a set of populations of organisms, the members of which are capable of exchanging genetic material under natural conditions by breeding to form fertile offspring". A few species are further broken down into subspecies, which are distinct populations that vary from each other in noticeable ways, but which are still capable of interbreeding with each other to form fertile offspring and are thus still members of the same species. Taxonomically, a group of species that are closely related to each other through anatomy and common descent are placed together in the same genus (the plural is genera). Species that are more distantly related are placed together in successively higher and more inclusive categories. A group of related genera forms a family, and a group of related families forms an order. Groups of orders form a taxonomic class, and a group of related classes forms a phylum (plural is phyla). A group of related phyla form a taxonomic kingdom, which is the highest category of taxonomy.

Biologists refer to a particular species by its scientific name, which is made up of two parts. The first half of the scientific name consists of the organism's genus designation, followed by its species name. If we are referring to a subspecies, then the scientific name will have three parts, consisting of the genus, species and subspecies designations.

All of the organisms in this book are animals. Biologically, the kingdom Animalia includes all of the multicellular organisms that do not have rigid cell walls and do not have chloroplasts for photosynthesis (rigid cell walls and chloroplasts are the distinguishing characteristics of plants). The animal kingdom is itself divided into a large number of phyla. The animals that we are most familiar with are all members of the phylum Chordata, which consists of all organisms which have a stiffened spinal tube or bony spinal column at some point in their lives.

The animals covered here, however, are all members of the phylum Arthropoda, which contains all of the various invertebrate organisms that possess a stiffened exoskeleton, usually made of chitin, and a number of multi-jointed legs and other appendages. Included in the arthropods are such diverse animals as insects, spiders, crabs, myriapods and scorpions. Invertebrate animals that do not have stiff exoskeletons and jointed legs, such as sponges, snails, clams and squid, are not arthropods. The arthropods are by far the largest of all the existing phyla, with a variety of species that dwarfs all the other living groups.

The animals covered here fall into two distinct classes within the arthropod phylum. The centipedes are members of the class Chilopoda, which differs significantly from the class Diplopoda, where the millipedes are placed. Biologically, these two classes are as different from each other as birds are from frogs or fish.

The classes Chilopoda and Diplopoda are further divided into a number of different orders. There are four different orders within the chilopod class, of which the Scolopendramorpha are the most important to hobbyists, while the most common pet millipedes belong to the Spirostreptida order within the diplopod class. Within each of these orders, a variety of different families are found. Most of the centipedes found on dealer lists are members of the family Scolopendramorphidae within the Scolopendramorpha order, while most of the petshop millipedes are members of the Spirostrepidae family. Each of these families contains in turn a wide variety of genera and species which identify their members.

While all of these tongue-twisting Latin designations and categories may seem like a waste of time, they are in fact vitally important to the hobby of keeping invertebrates as pets. For most people, all of these animals look superficially alike, and it is a virtual impossibility to tell one species from another. In many cases, however, identification may be very important, since some species can have environmental and husbandry needs that may be quite different from those of closely related species. Keeping a desert species of millipede or centipede in a rainforest habitat, for instance, will quickly kill it, and vice versa. In the case of potentially dangerous animals such as large centipedes, an accurate identification and the ability to distinguish harmless species from those that are potentially medically significant is an absolute necessity for the sake of safety.

Many of the invertebrates sold in the pet trade, however, are unfortunately identified only vaguely, if at all. Most are sold under a "common name" that may in fact have been made up on the spot by the importer or wholesaler. In some cases, the same animal may be offered through different dealers under completely different names. The large centipede Scolopendra subspinipes, for instance, can be found for sale under names ranging from "Vietnamese centipede" to "orange-legged jungle centipede" to "Asian forest centipede".

For all of these reasons, every effort should be made to obtain an accurate Latin name for any invertebrate pet you may purchase. Most of the larger and more responsible dealers will identify all of their animals by Latin name as well as common name. However, it must be recognized that the invertebrate animals are very poorly studied, and large gaps exist in our knowledge. A positive identification of the more uncommon species may depend on esoteric examination of genitalia or internal structures, and this can only be done by an expert --and the number of competent experts who are working with these animals can usually be counted on the fingers of one hand. A number of uncommon or unusual centipedes, for instance, particularly those being imported for the first time, can currently only be tentatively identified to the genus level. With some centipedes and millipedes, which are even more poorly known, even this level of identification may not be possible, and it is not unusual, for instance, to see millipedes that are completely unidentified, and carried on price lists simply as "class Diplopoda" (the biological equivilent of looking at a mammal and not being able to tell if it is a wolf or a deer). The problem of unidentified species is likely to get even worse as the hobby of keeping invertberates continues to grow, and importers begin bringing in more and more exotic and rare animals to enliven and expand their lists. A tremendous amount of work remains to be done in invertebrate taxonomy.

For the beginner, it is best to stick with the common and widely available species listed in this book, that can be readily identified by a full Latin name. This allows specific husbandry and care information to be researched as well as scientific and biological information. Save the more exotic and lesser known species until you have some experience under your belt.

Millipedes

Millipedes are members of the arthropod class Diplopoda. They are grouped together with the centipedes into the subphylum Myriapoda. The class name Diplopoda means "doubled feet", and refers to the fact that millipedes have two pairs of legs for each body segment, while centipedes have only one. (Embryonic millipedes have only one pair of legs per segment, but during their development adjacent segments become fused to form one, resulting in the same number of legs on half as many body segments.) Millipedes are known in the popular vernacular as "thousand-leggers", but few species actually have more than 250 pairs of legs (the record belongs to the species Illacme plenipes, which has 375 pairs, or 750 legs in total). Although they have many more legs than the fast-moving centipedes, millipedes are leisurely and plodding and are incapable of moving quickly.

There are several different groups of millipedes. Nearly all of the millipedes found in pet shops and dealer lists belong to the group known as spirostraptids. They are long and cylindrical, and are nearly round in cross section. The spirostrepdids move like tracked bulldozers, using their many legs and their flat faces to push their way through the substrate in search of food.

Another group of millipedes, the colobgnathids, have tapering bodies that they use to worm their way through leaf litter and dirt. The polydesmid group of millipedes has a prominent keel or ridge along the sides of their back, which they use to dig their way through soil or dirt. The glomerids and sphaerothiids look like large versions of pillbugs or roly-polies. They are shorter and wider than most millipedes, and curl themselves up into a ball when frightened.

All of the typical pet "millis" are slow-moving and easy to handle. They are inoffensive scavengers, feeding largely on decaying plant material, and lack the poison claws found in centipedes. Some of the large tropical millipedes, however, can secrete a noxious substance from the metathoracic glands on their cuticle when handled, and a few species are capable of defending themselves from predators by expelling a tiny cloud of repellant chemicals. Their usual defense mechanism is to curl the body like a watchspring, protecting the soft underbelly and exposing the hard chitinous shell. Millipedes have lived up to seven years in captivity.

Handling a Centipede

Handling a Centipede

The painful results of a centipede bite have been well known for centuries. In 1740, the English naturalist Charles Owen wrote, "The Scolopendra is a small venomous worm, and amphibious. When it wounds any, there follows a Blueness about the affected Part, and an Itche all over the Body, like that caused by Nettles. Its Weapons of Mischief are much the same as those of the Spider, only much larger; its Bite is very tormenting, and produces not only pruriginous Pain in the Fleshe, but very often Distractions of the Minde."

The venom apparatus consists of modified legs, on either side of the body just behind the head. These are known as maxillipeds, or sometimes as forcipules. The fang itself consists of a hollow tube with a sharp tip, like a hypodermic needle. The venom glands are found inside the body wall at the base of the fangs. When the centipede attacks, muscles surrounding the venom gland squeeze it and force venom through the hollow maxilliped and into the prey's body.

Very little scientific study of centipede venoms has been done, but it is known that some centipede venoms contain the active ingredient 5-hydroxytryptamine. The venom of the North American giant centipede, Scolopendra heros, contains cytolisins which break down cell walls.

Smaller centipedes, such as the orangish Scolopocryptops specimens found under rocks throughout the northeastern United States, produce nothing more than a painful but localized reaction, similar to a bee sting. The larger tropical species found in the pet trade, however, pack more of a punch, and can produce systemic symptoms as well as severe pain at the site of the bite---some people bitten by tropical scolopendromorphs have suffered nausea, vomiting, headaches and swelling in the lymph nodes. The centipede's venom can sometimes have a necrotic effect at the site of the bite, which can produce a painful open sore that takes some time to heal.

There is only one case in the scientific literature of a human death caused by a centipede bite -- a seven year old girl in the Phillipines died after being bitten on the head by a fullgrown tropical centipede, probably the large species Scolopendra subspinipes. Despite the potential danger, however, centipedes are not considered to be a major medical concern in any of the areas where they are found. Nevertheless, be aware that your pet centipede is a venomous animal, and treat it with the respect it deserves. A small percentage of people are allergic to centipede venom, and for these people any bite, no matter how small the pede or how weak the venom, can turn into a life-threatening emergency. If you are allergic to bee stings, the chances are good that you will also experience a reaction to centipede venom.

All of the tropical centipedes should be treated with caution. They should not ever be touched or handled with bare hands. If it is necessary to handle one, to move it to another tank for instance, great care should be exercised. These animals can move very quickly and bite readily, and unlike other animals that move rapidly away from potential danger, centipedes will immediately go on the attack towards any perceived threat.

Smaller centipedes are rather delicate and should be moved carefully. The best method is to place a small container (such as a deli cup) into the tank and then "herd" the centipede into it using an artist's soft-bristled paintbrush. Once the centipede runs inside the container, snap the lid on and it will be safely confined. This method can also be used (with more care) for larger tropical centipedes. To prevent escapes, transfer operations should always be carried out in an enclosed area to prevent the centipede from getting away if it makes a break for it. A bathtub works well (make sure you plug the drain). Keep all of your fingers well out of the way. If you offer a centipede any chance to get a fang into your flesh, it will happily oblige.

Some keepers handle their centipedes using a long pair of tongs or forceps that have been padded at the tips with foam rubber (a method also used to handle scorpions). If the tongs are at least twelve inches in length, the centipede will not be able to reach up and bite you with its fangs. This method should not be used by beginners, however---the exoskeleton of a centipede is not as thick as a scorpion's, and too much pressure can rupture the centipede's body wall and cause death. Centipedes also move very quickly, and it may be very difficult to grasp the pede without causing it to shed a large number of legs. It is far safer for both you and the centipede to prod it into a suitable container using a brush.

It may be best to slow down the centipede somewhat before attempting to move or handle it. This can be accomplished by placing the entire centipede tank in the refrigerator for about fifteen minutes. Centipedes, like all arthropods, are ectotherms and are dependent on their external environment for body heat. The cooler the temperature, the less quickly they are capable of moving. Keep in mind, however, that your centipede is a tropical animal, and cooling it to unnaturally low levels like this will cause it considerable stress. It may also kill the animal if cooled too far or too long. The idea is to cool it enough to slow down its movements, not to immobilize it.