There is a family of frogs called glass frogs (Centrolenidae) that live in Central and South America. They are called “glass” because they have lower sides that you can see through into the internal organs. For a biologist wanting to study the inner workings of frogs, this could be a handy feature.
Many of the species in the family of glass frogs use their transparent bellies for something more motherly. Most female frogs lay eggs and then leave them on their own. Biologists have found that glass frog mothers give the eggs several hours of special caregiving attention. After laying the eggs, the mothers press their transparent bellies against them. In doing this, the mother hydrates the jelly-like mass covering the eggs causing it to expand up to four times its size. This gives the eggs extra protection from predators who don’t want to dig through the all the slime to get to the frog embryos.
The mother sticks around for only a few hours, and then the eggs are on their own. In the frog world, even that much care from the mother is unusual. Researchers in the field found that if they removed the mothers before they had cuddled the eggs, the mortality rate at least doubled because of predators and dehydration. After the mothers leave, the frog fathers take over the job of hydrating the eggs and protecting them from predators.
Evolutionary biologists are fascinated by the unusual mothering activity of glass frogs and speculate on how this could have evolved. We think it’s part of the program that God designed for the survival of life.
© Roland Earnst