What is the world’s leggiest creature?

Female Illacme plenipes with 618 legs. Click to expaaaannnnd.

Illacme plenipes is a millipede. Mil in this sense indicates the number 1,000 (as in millimeter, one-thousandth of a meter), but no millipede seen so far really has 1,000 legs. This particular species has up to 750 legs, though, twice as many as any other known millipede species. Scientists first saw and categorized Illacme plenipes in 1926. They then lost sight of the species, and found it again in 2005 in the central region of California, near Silicon Valley.

With up to 750 legs, the millipede Illacme plenipes has more legs than any other animal on Earth.

This exceedingly rare millipede is known to reside in only 4.5 square kilometers in California. According to a report published in the open access journal ZooKeys, it also has the ability to spin silk from long hairs covering its back.

This millipede is leggy, but little, even relative to other millipedes. Females grow to just over an inch, and males are slightly smaller and have fewer legs.

A government scientist first spotted this creature in 1926. Nearly 80 years later, in November 2005, by Paul Marek, a Ph.D. student at East Carolina University, spotted Illacme plenipes again while conducting research on millipede systematics and evolution in California’s San Benito County. Marek published his discovery in the journal Nature in 2006.

Marek and his colleagues also provided further details on Illacme plenipes‘ surprisingly complex anatomy. It has body hairs that produce silk, a jagged and scaly translucent exoskeleton, and comparatively massive (given its small size) antennae that are used to feel its way through the dark because it lacks eyes. Its mouth, unlike other millipedes that chew with developed grinding mouthparts, is rudimentary and fused into structures that are probably used for piercing and sucking plant or fungal tissues. Read more at

Bottom line: Illacme plenipes is a millipede with more legs than any known creature on Earth. It can have up to 750 legs.

November 15, 2012

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