NewDelhi Dec 18 :A female Eumillipes persephone, with 330 segments and 1,306 legs. (Image credit: Paul E Marek, Bruno A Buzatto, William A Shear, Jackson C Means, Dennis G Black, Mark S Harvey, Juanita Rodriguez, Scientific Reports, Author provided)
Millipedes were the first land animals, and today we know of more than 13,000 species. There are likely thousands more species of the many-legged invertebrates awaiting discovery and formal scientific description
The name “millipede” comes from the Latin for “thousand feet”, but until now no known species had more than 750 legs. However, my colleagues and I recently found a new champion.
The eyeless, subterranean Eumillipes persephone, discovered 60 metres underground near the south coast of Western Australia, has up to 1,306 legs, making it the first “true millipede” and the leggiest animal on Earth.
Finding life underground
In Australia, most species in some groups of invertebrates are still undescribed. Many could even become extinct before we know about them.
Part of the reason is that life is everywhere, even where we least expect it. You could be excused for thinking remote areas of Western Australia such as the Pilbara and the Goldfields, where the land is arid and harsh, are not home to too many species.
But the reality is very different. An enormously diverse array of poorly known animals live underground, inhabiting cavities and fractures in the rock several metres below the surface.
One way to find out about these creatures is to place “troglofauna traps” far below the surface. E. persephone was found in one of these traps, which had spent two months 60m underground in a mining exploration bore in the Goldfields.
Why so many legs?
E. persephone was most likely driven to its underground life as the landscape above became hotter and drier over millions of years. We eventually discovered Jane was right about the nature of E. persephone: it is in fact a member of the Siphonotidae family, only distantly related to I. plenipes, and is therefore the only species in the whole order Polyzoniida with no eyes.
We classify any millipede with more than 180 body segments as “super-elongated”. E. persephone has 330.
With a genetic analysis, we found that super-elongation has evolved repeatedly in millipedes, and it might be an adaptation to living underground.
The large number of legs likely provides enhanced traction and power to push their bodies through small gaps and fractures in the soil. But this is just a hypothesis at this stage, and we have no direct evidence that having more legs is an adaptation to subterranean life.