What can be revealed by looking at a frog's foot?
You can tell a lot about a frog by its hands and feet. There are more than 6,500 species of frog from around the world, and each is adapted for living where it does. By looking closely at the size and shape of the hands and feet, you can often determine whether it lives in fast flowing rivers, pools, amongst thetrees, or whether it prefers a quieter life on the forest floor.
The most famously adapted hands and feet in the frog world belong to Asian Flying Frogs (genus Rhacophorus). These hands and feet are enormous and fully-webbed for a reason- they use them to parachute out of trees to the pools below- hence ‘Flying Frogs’! Living high in the canopy, they’ve developed a way to both escape from predators and get to the ponds quickly. Large finger- and toe-pads help with their life in the trees, too, allowing them to climb with ease.
Webbing is not just for flying, it's also great for swimming in strong currents. Many frogs adapted for life in fast-flowing streams and waterfalls use their webbing like flippers, helping them fight strong currents and not get washed downstream.
Other frogs prefer to stay out of the trees and spend their time in quieter waters or on the ground. Most of these less-adventurous frogs have slender fingers and toes without toe-pads or webbing.
Looking at the hands can also tell you whether a frog is a male or female. Many males have hard pads, bumps, or even spikes on their thumbs, and sometimes these extend onto the fingers. These ‘nuptial pads’ are only present in the breeding season and only in males, and are thought to help the males grab onto females.
The images on this page are a just a glimpse of the incredible variety of appendages among frog species.
You can read more from me on Frog feet in this month’s issue of Australian Geographic
Dr Jodi Rowley
Australian Museum Research Institute