Look at the world's tiniest vertebrate

The "world's smallest vertebrate" title has always been held by the powerful fish lobby — until now. But this little frog changed everything. Paedophryne amauensis shows us just how little spine an animal can have.

One of the questions troubling biology has been the exact scale at which life can sustain itself in certain forms. How big is a bunch of nerves, before it becomes a brain? How big or small can a single cell be? And, in this case, how small can a vertebrate get? Up until now, Paedocypris progenetica, a seven to ten millimeter fish was declared the smallest vertebrate on the planet. Then, in Papua New Guinea, a teeny little frog that comes in at an adult size of seven to eight millimeters stepped up to the plate.

The discovery of this particular frog has more significance than the need to update to The Guinness Book of World Records. This smallest of vertebrates is one of two new diminutive species of frog discovered in the area. Researchers have noticed that fish and frogs have always been neck and neck when it comes to claiming the title of the smallest vertebrates. While the origins of certain fish are murky, past species of tiny frogs have been found in widely separated habitats, meaning that multiple frogs evolved down to this size independently of each other. With the discovery of this new species, scientists are beginning to consider that there may be an ecological or evolutionary reason why frogs gain an advantage to such a small frame. What is it about their lifestyle, environment, or physiology that makes having the tiniest spine in the world a evolutionary benefit? Hopefully we'll find out soon.

Via PLoS ONE.