Wednesday, May 2, 2007

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 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.

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