Saturday, February 27, 2010

Toe Pads & Tails

The adhesive toepads of lizards are one of life's most spectacular inventions. Humans are even using this innovation as the inspiration for new adhesive nanostructures. Did you know that some geckos have similar adhesive structure on the tips of their prehensile tails, as well as on their toes? I caught one such gecko in northern Australia a number of years ago during an expedition to Arnhem Land with Jane Melville and Museum Victoria. The species we found - Pseudothecadactylus lindneri - is closely related to geckos on New Caledonia and could be found wandering Arnhem Land's impressive rock outcrops at night. The photo above is of a juvenile P. lindneri and close-ups of the toepads (top) and tailtip (bottom) of an adult animal. It seems likely that the tailpad results from similar genetic and developmental mechanisms to the toepads found in the same animal, but this has yet to be investigated in any detail. Remarkably similar toepads are known to have evolved independently in geckos, anoles, and skinks.


Luke Mahler said...

Really cool, and a very timely post! I'm teaching the labs for Jonathan Losos and Jim Hanken's herpetology class, and we did lizards about a week ago - including a station on toe pads. I looked all over for geckos in the Harvard MCZ herp collection that had these "toe pads" on their tails, but it can actually be a pretty tough structure to see by eye in a lot of the species that have this trait (e.g., the African Lygodactylus and a smattering of diplodactylines from Australia, New Zealand, and nearby areas - I was using Bauer 1998 as my road map).

Your picture of a live Pseudothecadactylus is probably the best I've seen this illustrated. I have to say, I was surprised to find no one had really done much more with this (although feel free to steer me towards work I missed)! Such a cool example of evolutionary heterotopy.

Luke Mahler

Susan Perkins said...

I love the first sentence of the abstract of the paper: "If geckos had not evolved, it is possible that humans would never have invented adhesive nanostructures. "

The last sentence is also fantastic.