What is that sound? A persistent buzz, perhaps? Mechanical? It’s coming from a particular location, and you hear it there, in that same place, in the daytime.
Is it an insect? A power tool? Or maybe it’s the sound of one of the rainforest’s tiniest citizens, the Blue Jean Poison Dart Frog.
Scientists call this iconic species Oophaga pumilio. It is part of a family of diurnal frogs called Dendrobatidae, a family of small colored frogs, many of which carry very powerful poisons. They are known as poison dart frogs because a few of the species, especially a larger golden frog member of this family from Panama, have been used by indigenous peoples to hunt.
They are beautiful little frogs that can help us understand how complex and strange a rainforest is. These frogs feed on small-sized prey such as termites, mosquito or ants, but the most valuable for them are the ants of the genus Brachymyrmex and Paratrechina. These ants feed on plants that synthesize alkaloids and the ants use these alkaloids as a method of defense against predators. Frogs feed on the ants and after absorbing the poison the frogs transport it to special glands on the skin. This way the frogs can use it to defend themselves against the animals that intend to eat them.
Since the members of this family of frogs do not directly synthesize the poison, you may find some frogs of this family that are not poisonous. Here’s a “tell” that helps identify if the frogs are poisonous or not. If it’s not poisonous, the frogs will flee if a predator comes upon them. In contrast, very poisonous frogs let predators see them. They try to educate the predator: Do not eat any red frogs because all you see are very poisonous.
Male poison dart frogs defend large dry leaves on the ground in the morning. When a female decides she wants to breed with a male, she leaves an egg on one of the leaves. The male, after fertilizing it, must put water on it between 7 to 9 days until it hatches. When the egg hatches, the mother comes back and carries the tadpole on her back. She transports it to a small body of water, usually on a plant in the Bromelias family. The male sometimes helps in this task. From there the mother will return to see the tadpole every 3 to 5 days to feed it with infertile eggs. That’s why they are called Oophaga (Latin egg-eating). If the mother has had the opportunity to feed on many ants and the ants had the poison, the infertile eggs will allow the tadpole to use the poison to defend itself. It is the only known species that performs tertiary transfer of venom to defend its offspring.
We hope you liked the story of the little red frogs. In Video 1 you can see how these frogs behave, was recorded by the Inbio and is very didactic. Someday not too far away we will talk about their poison and how humans have used them to hunt and why. Have a good week.
Video 1: Poison Frog Oophaga pumilio