The Translucent Glass Frogs of the South American Rainforest

There are many natural wonders in the animal kingdom, perhaps none so unusual as the Glass Frog. This tiny frog gets its name because of the translucent skin on its underside (and in some species the top as well) that allows you to see its inner organs, right down to its beating heart!

Glass frog showing its inner organs

This actually has an advantage for the glass frog. First of all, it makes him very difficult for predators to spot, as he almost becomes a part of the leaf he is sitting on. If you shine a light on a tree frog at night (if you can find one) all you will see are his eyes and a smudge for his skull.

Glass frog on a finger tip

Glass frogs are very small, the average one being between 1.4cm and 3cm, and they generally live in the rainforests of Central and South America. If they are high enough up, these rainforests are called cloud forests as the canopy is wrapped in cloud – and this is a further reason for which the glass frog’s transparency is very useful. Although they live by streams and rivers, almost all of the glass frogs are arboreal, only coming lower to breed.


Glass frog on a bird of paradise plant

Breeding happens closer to the streams and rivers, anywhere from 10 to 20ft up in the air, where eggs are laid on leaves. This protects them from predators in the water, though there is a small danger from the maggots and larvae of wasps, so parents do keep an eye over the eggs. When ready to hatch, the tadpoles, which are born with a strong tail and fins, fall into the river down below and the parents return to the canopy.

Image: bgv23


Glass frog with eggs

Many think the glass frog looks a lot like some green tree frogs but you can always tell the difference by looking at their eyes. Glass frogs’ eyes face forward, while tree frogs eyes are at the side. Other ways to tell specific species apart are from the colors of their bones. The bones are visible from outside and in some species (including the Pichincha glass frog, the Pacific glass frog, the Cochran glass frog and lots of others) the bones are green while in other species they are white.

Glass frog on reeds

There are 134 species of glass frogs with 60 of them threatened. Of the rest, 49 are classified as having “not enough data” to classify their status. Glass frogs are important because they are a bioindicator. As the climate changes, studying how the glass frogs cope will indicate how the other flora and fauna are handling the changes as well. Nature in all its diversity is a wonderful thing and we can’t afford to lose any more species to logging or to habitat destruction in the rainforests.

Sources: 1, 2, 3