Good news for lovers of all things tiny and alive: scientists have just discovered two new species of frogs that out-tiny all other frogs. These little critters live in the forests of Papua New Guinea and are each smaller than a single M&M.

The Hawaiian vertebrate zoologist Fred Kraus discovered these bite-sized amphibians on an expedition to an isolated mountain on the island. The frogs are so small that he and his team didn't even see them at first; they tracked them down by following the calls the critters make to communicate with each other. The frogs survive on the leaves of the rainforest floor, hidden away from the world of regular-sized animals. They subsist on mites and other diminutive prey too small for bigger creatures to eat. They likely evolved to be so small in order to feed on such prey without competition and also to avoid the eyes of larger predators.

 

Not only are these bug-sized hoppers the smallest frogs we've yet discovered, they're also the smallest tetrapods--four-legged vertebrates--that we know of. They can't quite claim to have the smallest spines on the planet, though. That honor belongs to a fish in Southeast Asia called Paedocypris progenetica that grows to be just under 8 millimeters long at its most mature state. The Paedophryne dekot and Paedophryne verrucosa frogs, by comparison, check in at about 9 millimeters in length. That's a whole millimeter smaller than the last tiniest frog on record, also within the same genus discovered by Kraus.

 

As you might expect, it's not easy to capture a frog that small--even if you're an experienced zoologist. Kraus noted the difficulty he and his team had with catching the little dudes, who nimbly hopped around and hid under leaves on the forest floor. His assistants and he had to crouch down and wait patiently for a frog to hop into their bare hands. Kraus predicts that they're not alone in their microcosmic world, figuring that other species must have evolved to smaller and smaller sizes for the same evolutionary reasons as the frogs. Many areas within the tropics are not terribly well surveyed for animal life, and it's entirely possible that there are miniature worlds lurking just out of sight.

 

Who knows what kind of micro-creatures we'll find next? With the likes of Kraus and his team hard at work, I have no doubt that other similarly minute living beings will pop up from their hiding places.