Soil Science

Millipedes

Millipede - note round shape.
Millipede - note round shape.

Millipedes, like centipedes, are members of the myriapod group of soil animals - a scientific term which means "many legged". This is certainly the case with millipedes. Although their name suggests that they have 1,000 legs, this is not necessarily so! Even though each segment has two pairs of legs attached to it, the maximum number of legs on any millipede is about 376 pairs and multiplying by 2, this gives only 752 legs.

Note 2 pairs of legs on each dark-banded segment.
Note 2 pairs of legs on each dark-banded segment.

Millipedes are segmented (or banded) animals with a hard skin. The head of the millipede pictured here is on the left hand side - you can see one of its antennae.

The bodies of millipedes are more rounded than those of the predatory centipedes. They differ in other ways too in that millipedes mostly feed on decaying vegetable matter - also they do not bite!

Millipede in compost. Note the skeletonised leaves where the millipede has eaten the soft part between the harder leaf veins.
Millipede in compost. Note the skeletonised leaves where the millipede has eaten the soft part between the harder leaf veins.

They hide under rocks and logs or in rotting wood and are also good burrowers. They eat their way through soil forming burrows and absorbing organic matter food along the way.

When disturbed, millipedes can react in several ways. See below for more information.

The introduced Portugese millipede can be a nuisance in South Australia where, in autumn and spring, they are attracted to lights and invade houses in vast numbers.

Millipede defences
Millipedes curl up into a spiral to protect their vulnerable undersides against predators. They can also exude a repellant yellow substance which is toxic and foul tasting, presumably to discourage predators. It is harmless to humans although it may cause a reddening of the skin. Usually only a stained hand results.

Millipede curled into a spiral when disturbed.
Millipede curled into a spiral when disturbed.

Millipedes also curl up to prevent water loss through holes, called spiracles, on the underside of their bodies. These cannot be sealed off as in insects when it gets dry and so are not very effective in preventing water loss from the millipede.

Believe-it-or-not: Millipedes can stop trains! Millipedes are normally the "goodies" of the underworld and do a great job of decomposing organic detritus. But during mass migrations in autumn, their squashed bodies can stop trains as the wheels lose traction on the rails.

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