Litinsects #40: Millipedes
The level of disgust for an arthropod often increases proportionately with the number of legs it has. Well I’m here to tell you: you don’t really need to fear millipedes!
What is a millipede? Millipedes and centipedes (more on them to come) both belong to a group of arthropods called the MYRIAPODA. Why? Because they have a myriad of feet! Myriapoda are one of the four arthropod groups, the others being arachnids, crustaceans, and hexapods (aka insects).
Millipedes are known as DIPLOPODA from the Greek “diploos” meaning double and “pod” meaning foot. Have a look at the close-up photo and see if you can guess why... With the exception of the first four body segments behind the head, every other segment of a millipede is actually two fused segments, known as a DIPLOSEGMENT, so it appears as though each one has TWO legs attached rather than one, hence the name!
Millipedes are some of the very earliest animals to colonize land, around 450 million years ago!
No millipede actually has 1,000 legs. Most species have between 30 to a few hundred. The record-holder for most legs in the animal kingdom goes to the millipede Illacme plenipes, which has 750 legs! If you’re imagining something terrifying right now... rest easy because they’re only about 4 cm long
On the other hand, the extinct ARTHROPLEURA grew to 2 meters long and almost 50 cm wide and was probably one of the largest land-dwelling invertebrates of all time! Nowadays, the largest EXTANT (still living) species is the giant African millipede, measuring up to 38 cm.
- Millipedes move their legs in a wave-like motion from back to front, with multiple “waves” at a time
Most millipedes are DETRITOVORES or HERBIVORES and only a small number of species are predatory. They are NOT VENOMOUS and relatively harmless to humans.
Their main defense is rolling into a ball (see photo) to protect their legs and underside. However some also secrete smelly defense chemicals when threatened (so be careful when touching them if you are so inclined). Super interesting: some monkeys have been observed using millipede chemical excretions on themselves as insect repellant!
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