The cloud forests of South America are home to some of Earth’s most extraordinary creatures, but few are as intriguing as the glass frog. Seen from above, most glass frog species look pretty nondescript, but a glimpse of their underbelly reveals a fascinating anatomical anomaly: translucent abdominal skin. From underneath, a glass frog’s heart, liver, and various other internal organs are often completely visible.
The glass frog couldn’t be more aptly named. After all, his entire underbelly is translucent like glass. Amazingly, that’s not the only unique thing about these beautiful creatures. They’re also one of the handful of critters where the father actually handles all aspects of parental care. Females flee as soon as they have delivered the eggs. Then males stay during weeks in close proximity of the egg clutch, improving its survival probability by maintaining it wet and, sometimes, scaring away predators.