Wednesday, May 2, 2007

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.

1 comment:

Frenchie Powell said...

Hey thanks for posting this! I'm currently obtaining millipedes for composting purposes at Eckerd College, and I'm doing general searching about their lives and uses! This article was very helpful :)