Friday, June 09, 2006

Most leggy millipede


The world's "leggiest" millipede has been rediscovered 80 years after its first and only sighting.

Illacme plenipes has up to 750 legs and is found in a tiny area of San Benito County in California, US.

Of the 10,000 species of millipede described, I. plenipes comes the closest to possessing the 1,000 legs that its name would suggest.

Scientists, writing in the journal Nature, highlight the need to protect its fragile habitat.

A colony of the leggy millipedes was first spotted in 1926, but despite numerous efforts to re-locate the creatures, I. plenipes remained elusive.

"When I learned about the leggiest millipedes, I thought this would be a great organism to find," said lead author Paul Marek, a PhD student from East Carolina University, North Carolina.

Mr Marek set off, with his brother in tow, armed with vague geographical information from 1920s research and topographical maps to see if they could pinpoint the mysterious animal.

"My brother and I were looking around and we both spotted it at the same moment. It was just staggering," he said.

Over the course of three field trips, researchers unearthed 12 of these cream-coloured, leggy arthropods - a class of creatures with segmented bodies and jointed legs that includes spiders, insects and crustaceans.

The captured females were found to have between 662-666 legs, over 170 segments and measured about 33mm (1.3in) long. The males, in comparison, were about half of the females' length with between 318 and 402 legs.

All of the specimens measured a thread-like 0.57mm (0.02in) in width.

The scientists believe the varying lengths are explained by the fact that millipedes continue to grow additional segments and legs even after they have reached sexual maturity - so the 750-legged millipede found in 1926 may have been an older specimen.

The millipedes also showed some other unusual features when examined more closely.
"We looked at them under a scanning electron microscope and we found a very complex and intricate morphology, including spikes and spines, and also the presence of setae (a type of bristle) on the back of the millipedes that secrete this silk-like substance," Mr Marek said.

"These were found on every segment on their backs, and we have no idea what this silk does."

I. plenipes is only thought to exist in a 0.8sq km (0.3sq mile) area of the biodiversity hotspot California Floristic Province. The team has called for urgent protection of the rare creature's fragile habitat.

But the researchers say the species' location may also point to clues about its past.

Other closely related species belonging to the same family as I. plenipes, Siphonorhinidae, are found in other narrow geographical ranges in southeastern Africa, Sumatra, Indo-Burma, Sumatra, Malaysia and Java.

The team believes this unusual distribution hints that the age of this particular family pre-dates the break-up of super-continent Pangaea over 200 million years ago.

Source: BBC News

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