The leggiest animal on Earth lives in the outskirts of Silicon Valley

Nov 14, 2012
This is the habitat of Illacme plenipes. Oak forest in California where I. plenipes were encountered (composite stitched landscape image of three photos, image sides slightly distorted). Credit: Dr. Paul Marek et al.

With 750 legs, the millipede Illacme plenipes is the leggiest animal on Earth. Once believed extinct, scientists rediscovered the species in 2005—more than 80 years after it was first described. This exceedingly rare millipede is known from a single 4.5 km2 area in California, and based on new details recently published in the open access journal ZooKeys, the millipede has a beautifully intricate anatomy including the ability to spin silk from long hairs covering its back.

The leggiest animal in the world, the millipede lllacme plenipes, was re-discovered several years ago in California by Paul Marek. Now, Marek and his colleagues provide further details of the surprisingly complex of this diminutive creature and its extreme rarity, limited to a handful of spots just south of San Francisco. More details about the and its biology can be read in an article that was recently published in the journal ZooKeys.

Millipedes have the most legs of any . From their with just one pair of legs per body segment, evolved two pairs (four total) through segmental fusion. This of segments happened deep in the of millipedes, more than 400 million years ago. Four legs provide more thrust on a per segment basis, which benefits millipedes to help them burrow underground—e.g., to escape or access new resources. Those individuals with a coalescence of segments and hence a better burrowing ability, were able to persist in this early primordial ecosystem.

This video is not supported by your browser at this time.
This is a movie of Illacme plenipes with 662 legs showing live movement. Credit: Dr. Paul Marek

The most noticeable thing about millipedes are their number of legs, which lined up along their bodysides step in synchronous "metachronal waves". The acme of legginess in millipedes, and all animals for that matter, is the Californian species Illacme plenipes (literally meaning "in highest fulfillment of feet"). The females have up to an astounding 750 legs, outclassing the males who only have a maximum leg count of 562. The proliferation of legs may be an adaptation for its lifestyle spent burrowing underground or (based on the presence of features like legs with bifurcate claws and other traits known to be associated with rock-climbing in millipedes) enable it to cling tightly to the sandstone boulders found exclusively associated with the species in its habitat

"This relict species is the only representative of its family in the Western Hemisphere. Its closest presumed relative, Nematozonium filum, lives in South Africa and this early relationship was established more than 200 million years ago when the continents coalesced in the landmass Pangaea", said the lead author Dr Paul Marek, from the University of Arizona.

Not only is this species the leggiest animal known on the planet, it also has surprising anatomical features: body hairs that produce silk, a jagged and scaly translucent exoskeleton, and comparatively massive (given its diminutive 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.

This rare and ancient-looking creature's home is California, on the outskirts of Silicon Valley. The species is exceedingly scarce and limited to just a single tiny area near San Juan Bautista, just east of the San Andreas Fault. Based on the known environmental conditions where it lives, the species' probable distribution elsewhere in California was inferred. Yet still restricted to a small geographical range, the analysis indicated other areas of suitability limited to the terrestrial areas on the edge of Monterey Bay eastward to San Juan Bautista and throughout the Salinas Valley. What's unique about this area, and seems to be correlated with the model's area of highest suitability, is the thick layer of fog that accumulates in the area—like soup in a deep bowl. The fog and the species' unique set of features in its habitat (oak forests, sandstone boulders, and fine sandy soil) make this area a special place and certainly deserving of attention as the home of this rare and superlative beast.

Explore further: Alternate mechanism of species formation picks up support, thanks to a South American ant

More information: Marek PE, Shear WA, Bond JE (2012) A redescription of the leggiest animal, the millipede Illacme plenipes, with notes on its natural history and biogeography (Diplopoda, Siphonophorida, Siphonorhinidae). ZooKeys 241: 77. doi: 10.3897/zookeys.241.3831

Related Stories

Millipede feared extinct is found

Jul 31, 2006

U.S. biologists say Illacme plenipes, a millipede with up to 750 legs that was last seen 80 years ago, has been found in California.

The secret life of millipedes

Aug 21, 2011

Male adult helminthomorph millipedes usually have one or two pairs of legs from their seventh segment modified into sexual appendages. These specialized gonopods are used as claspers to hold the female during ...

Millipede border control better than ours

Dec 23, 2011

A mysterious line where two millipede species meet has been mapped in northwest Tasmania, Australia. Both species are common in their respective ranges, but the two millipedes cross very little into each other's ...

Millipede family added to Australian fauna

Aug 30, 2012

An entire group of millipedes previously unknown in Australia has been discovered by a specialist – on museum shelves. Hundreds of tiny specimens of the widespread tropical family Pyrgodesmidae have been ...

Glow-in-the-dark millipede says 'stay away'

Sep 26, 2011

As night falls in certain mountain regions in California, a strange breed of creepy crawlies emerges from the soil: Millipedes that glow in the dark. The reason behind the glowing secret has stumped biologists ...

Recommended for you

Orb-weaving spiders living in urban areas may be larger

Aug 20, 2014

A common orb-weaving spider may grow larger and have an increased ability to reproduce when living in urban areas, according to a study published August 20, 2014 in the open-access journal PLOS ONE by Eli ...

User comments : 6

Adjust slider to filter visible comments by rank

Display comments: newest first

Eikka
1 / 5 (3) Nov 14, 2012
Has there ever been a true milliped? As in, a bug with a thousand legs.
Doug_Huffman
1 / 5 (9) Nov 14, 2012
Has there ever been a true milliped? As in, a bug with a thousand legs.
Absolutely. There is no reason in principle not to be. To prove otherwise requires examining the entire universe of discourse - all many legged bugs that have ever been.
david_king
1 / 5 (8) Nov 14, 2012
Finally a creature that can actually tie itself in knots, a lot of knots if it wanted to.
FrankHerbert
2.6 / 5 (5) Nov 14, 2012
Has there ever been a true milliped? As in, a bug with a thousand legs.
Absolutely. There is no reason in principle not to be. To prove otherwise requires examining the entire universe of discourse - all many legged bugs that have ever been.


Kind of like disproving a god would require combing over every planck volume of the universe, right? So thinly veiled, Doug.

How do you feel about the recent election?
gwrede
1 / 5 (6) Nov 14, 2012
This one seemed like there is a risk knotting himself.

Perfect recipe for disaster: walk through a couple of loops of yourself, and then run in panic.
Eikka
1 / 5 (4) Nov 15, 2012
Kind of like disproving a god would require combing over every planck volume of the universe


Actually, the only thing you need for disproving God is to point out that you can't find one.

Because that which can't be found, in contrast to simply not having been found yet, is something that doesn't exist in this reality. It has no influence on us - otherwise we'd be able to distinguish and measure it - at least in principle.

As long as God is defined as unknowable and beyond all reasoning, it remains impossible to discover, and therefore it cannot be real. If God is knowable, then the burden of proof shifts to the believers who must prove that God exists before anyone has any reason to believe so.

The God of the Bible for example cannot exist, because it is described with contradictory qualities. Finding something like the biblical God is like finding a square circle.