The Hyalinobatrachium genus of frogs has transparent bellies. The unusual look soon earned the tiny amphibians the title of “glass frogs.” Found in Central and South America, the see-through skin of two species extends over the chest and show their hearts.
In 2017, a third glass frog was found to beat its heart openly at the world. Called H. yaku, it was a bit odd. A visible heart is already a weird thing to find in nature, but H. yaku also looked different than other glass frogs.
All other species take some thinking and perhaps a magnifying glass to tell them apart. H. yaku turned up in Ecuador’s trees sporting unique green spots and distinctive songs. They also had bright green to yellow-green skin. Interestingly, DNA tests showed that this frog was not closely related to the other two species with visible hearts.