The Mystery Behind Two Newly Discovered See-Through Frogs

Planet Earth produces some of the most mystifying creatures. If you spend enough time exploring, you'll find star-nosed moles, glow-in-the-dark sharks, wingless wasps that look like pandas, and of course, see-through frogs.

Frogs adorned in transparent ventral skin have a rather unique physical attribution — you can look right through their flesh to see their organs (via PNAS). These translucent creatures are known in the scientific community as glass frogs. Their skin, which craftily displays their insides like transparent glass, is a kind of high-fidelity camouflage meant to disguise them from predators. The fact that the skin exposes their tiny red beating hearts is really just an interesting consequence of that disguise.

Looks can be deceiving, especially in creatures that are crystal clear. Take, for example, science's latest discovery: two new glass frog species whose camouflage is beyond skin deep. The real mystery here is not the Frankenstein-esque display of reptilian organs exposed in full view like a high school science class dissection. Freakier still is what scientists found in their DNA (via National Geographic).

National Geographic reports that Juan Manuel Guayasamin, an evolutionary biologist and the author of the PeerJ article detailing this event, made the following statement regarding the odd amphibians: "At first, we started to collect them, we thought they were the same species."

And on the surface, they absolutely were. The frogs were roughly the same size, with piercing lime greenbacks and clear bellies. Bulging yellow eyeballs wrap around their unmistakable smiles, and their see-through skin is spotted with microscopic black dots, making the frogs look a bit like pepper spilling into a bowl of Jello. They were even found within 13 miles of one another and were spotted hanging out in similar altitudes, temperatures, and atmospheric conditions.

It wasn't until DNA tests were conducted that scientists discovered the frogs possessed diverse DNA and were actually two different species. Their genetic divergence awes at 4.6- 4.7%, a gap that is uncommon for species that look this similar on the surface. Experts suspect that the valley at the edge of the Guayllabamba River served as a geographic barrier, separating a frog species that might have initially been the same but over time developed an accumulation of genetic mutations that made them quite different under the microscope.

Imagine twins separated at birth and raised within just a few miles of each other, but one lives in a rural farm town while the other resides in a bustling city. Their whole lives, they are separated by a bridge at the border where the city sidewalks end. This is essentially the existence of these two frogs. Their DNA tells the tale of a divided, little-known region and, on a larger scale, the hidden diversity that exists there. According to PeerJ, it is not at all uncommon to find "sister species" in the Toisán mountain range, particularly between the Mira river valley and the Intag-Guayllabamba river valley.

The north-residing frog and the south-residing frog never meet but share a wealth of similar characteristics that are immediately recognizable to observers. According to National Geographic, both enjoy swaying from the undersides of leaves guarding transparent eggs with their encapsulated offspring inside. The H. mashpi frog even makes a sound similar to a different frog that is scientifically referred to as H. valerioi. Both of these frogs' vocals are reminiscent not just of another species but of an entirely different creature — namely, the cricket.