Millipedes, just like centipedes, are arthropods -- they have bodies made up of numerous segments. Newly hatched millipedes usually have only three pairs of legs, adding legs as they grow. But contrary to what its name may imply, the millipede does not have a thousand legs. In fact, Illacme plenipes which is a very thin millipede and considered to be the world’s leggiest animal only has 750 legs.

The first four segments of a millipede bear three single pairs of legs, while the succeeding segments all have two pairs. But with that many legs, how does a millipede use them? Veverle San Juan, a project entomologist at the UPLB Museum of Natural History says that millipede legs have various special uses.

First pair: Roughing it

"The first pair of the millipede's legs are mainly used for eating leaf litter, decomposing materials, microbes, and fungi," San Juan shared during the Museum's recent Biodiversity Seminar Series last 12 March 2014.

Do millipedes eat live organisms and plants? "It is hardly believable that millipedes can eat live animals but millipede infesting crops is common in temperate countries. In the Philippines, we have a 2011 report of a "millipede attack" on crops in Itbayat, Batanes but it should be also verified,” she said.

Pair number two: Dribble, aim and dunk

The second pair of legs, in all adult male millipedes, carries the gonopore or the outlet of the male reproductive system. Interestingly, this second pair of legs must hand off the semen onto a pair of gonopods, which then inserts (the semen) into the females' cycophods or vulvae.

"When male and female millipedes face each other to mate, the female’s vulvae at its 2nd segment is aligned with the male’s gonopod (at the 7th segment),” San Juan explained.

"So basically, the male hands off its semen to the more specialized gonopods in its seventh segment which then goes deep into the vulvae for insemination," she elaborated.

Pairs three, four and five

Pair number three, San Juan reported, is the last singular leg in the millipede’s body and is used for walking.

“The fourth and fifth pair of legs are also just walking legs, but are considered special because they are on the fifth segment, where ozopores are found,” she followed.

In the fifth segment of the millipede, and other segments further the millipede body, there exists openings called ozopores. "Millipedes have special glands that produce noxious chemicals, and they are released via the ozopores during self-defense," San Juan added.

According to San Juan, “once under threat, millipedes coil to protect its head and its first four segments which are defenseless," the speaker said. Some millipedes have hard exoskeletons, while a few have modified extensions called keels, making them look spiny and become less of a treat to larger predators.

Six and further: Not just for walking

San Juan shared that beyond the millipede's 3rd leg pair, the practical use for having that many legs is not only just for the long walks. These also provide strength and support for bulldozing, burrowing and wedging.

“Further down a millipede’s body, with the exception of the seventh where the gonopods are located, the legs have no other modifications or special functions,” she added.

"But mind you, even though millipedes are very small and slow creatures, their presence in several areas can indicate geographical connections," San Juan explained. According to San Juan, "these organisms cannot fly nor be carried by wind; if we find the same millipedes in two separate areas bounded by water, it is either they have been brought there or, more interestingly, the two areas must have been connected by land in the past."

San Juan, a licensed forester and a recent MS Entomology graduate has discovered in 2010 with MNH Director Ireneo L. Lit, Jr. two new species of flat-backed millipedes in Polillo Island in Quezon.

In her studies, San Juan also contends that it is very likely that new myriapod taxa await discovery elsewhere in Polillo and in the entire Philippine archipelago.

Presently, her search for Philippine Platyrhacidae (flatback millipedes) have extended the range of occurrence of these millipedes. The Platyrhacidae has now been recorded in several areas in Luzon mainland, islands in the Visayas and a location in Mindanao.#


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