So-called "glassfrogs" are known as such because the skin on their bellies is transparent, leaving their lower abdominal organs visible. In a newly-discovered species of glassfrog from Amazonian Ecuador, however, that transparency extends to the animal's chest. This means that if you catch one and flip it over, you can see its beating heart.
Named Hyalinobatrachium yaku, the frog was discovered by a team from Ecuador's Universidad San Francisco de Quito, led by Dr. Juan M. Guayasamin. In the region's local Kichwa language, yaku translates to "water," as glassfrogs reproduce in and around slow-flowing streams.
Besides its see-through chest, the new variety is also unique in having large dark green spots at the back of its head and the foremost part of its body, plus it has a distinctive long call. Another unique feature is the fact that males – in most places, at least – make their mating calls while hanging on the underside of leaves. They also look after egg clutches.
Given that the frogs only reach a length of about 2 cm (0.8 in) and the males hide under leaves, it's not surprising that they hadn't been discovered previously.
So far, the frogs have been found in three locations, each approximately 110 km (68 miles) apart. At the first two places, they were found on the underside of leaves hanging above streams. At the third, however, they were found on top of leaves that were over 30 meters (98 ft) from the closest stream.
A paper on the discovery was recently published in the journal ZooKeys.