In Peru there lives a fantastically decorated frog.
It has skin the color of chocolate and it is dappled with polka dots – lots and lots of polka dots, all over its body.
H. Zell, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons
Scientists call this frog Excidobates mysteriosus. Like its scientific name suggests, this frog has some mysteries about it.
Why does this frog have polka dots?
To humans these polka dots look like cool decorations. To potential predators, though, they send an entirely different message: “Don’t snack on me.”
The skin of this frog is full of poisons that will kill any snake, bird, or other animal that eats the frog. The polka dots serve as a brightly patterned warning that this frog is not edible. The scientific term for this kind of warning coloration is aposematism.
How can an animal that needs to live in water survive in a dry forest?
Excidobates mysteriosus lives in dry forests in hilly areas of Peru. Frogs need water to lay their eggs in and develop from tadpoles into frogs.
Excidobates mysteriosus solves that problem by living in large plants called bromeliads. Water collects in the bromeliad and forms tiny ponds that the frog lays its eggs in. The eggs hatch into tadpoles, and the tadpoles develop into frogs all within these tiny ponds.
Here (image on the left) is a picture of a bromeliad growing on the side of a tree. Pools of water collect in bromeliads (image on the right):
The bromeliad is almost the entire world for Excidobates mysteriosus. The bromeliad flower hangs over the small pond within it like a big umbrella. This prevents the water from evaporating and shields the frogs from the hot sun in the dry forests in which they live.
The forests where Excidobates mysteriosus lives occur only in a very small area of northwestern Peru. Most of the forests in this region have been cut down. For many years this frog was thought to be extinct. It was rediscovered in 1989 after not being seen by scientists for 60 years.
How will Excidobates mysteriosus survive into the future?
Even though the frog is protected from predators by its aposematism, it is not protected from humans who have cut down most of its habitat. Excidobates mysteriosus is known from only three patches of bromeliads. People in Peru are working to protect and expand the frog’s habitat. Hopefully this frog can continue to decorate its habitat with its fantastic polka dots well into the future.
By David Brown
Learn more about this frog and other Dendrobates frogs on dendrobates.org:
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