Amphibians
Strawberry Poison Frog
Oophaga pumilio · also called strawberry poison-dart frog, blue jeans frog
The strawberry poison frog is smaller than a thumbnail and, in its best-known form, bright red with dark blue legs, which is why people call it the blue jeans frog. Its poison is real but borrowed from the ants it eats, and its family life is extraordinary: the mother carries her tadpoles up a tree one by one and then returns for weeks to feed each of them her own unfertilised eggs.
Overview
The strawberry poison frog, Oophaga pumilio, is a tiny day-active frog of the Caribbean lowlands of Central America, from Nicaragua through Costa Rica to Panama. It hunts ants and mites in leaf litter, and it comes in a remarkable range of local colour morphs — red-and-blue, orange, yellow, green, white, near-black — some changing over just a few kilometres, especially across the islands of Bocas del Toro.
Borrowed poison
The frog cannot make its own toxin. It sequesters alkaloids from its wild diet of ants and mites and stores them in its skin. A captive frog fed crickets and fruit flies is completely non-toxic. The wild frog’s poison is much milder than the golden poison frog’s — painful in a cut or the eyes, not deadly.
Carrying the brood upstairs
Eggs are laid in moist leaf litter and kept damp by the male. When they hatch, the female lets one tadpole at a time climb onto her back and carries it high into a tree, depositing it in the water pocket of a bromeliad leaf, spreading her brood among several pools. Because those pools hold no food, she comes back every few days to feed each tadpole a clutch of unfertilised eggs until it leaves the water six to eight weeks later.
Status
The species is Least Concern but decreasing, mainly from the clearing of lowland rainforest for pasture. Several of the small-range island morphs are more vulnerable, both to habitat loss and to collection for the pet trade.
Strawberry Poison Frog: common questions
Why is the strawberry poison frog called the blue jeans frog?
The name refers to the commonest and most widely pictured colour form, found on the Central American mainland, in which the frog has a brilliant strawberry-red head and body and abruptly darker blue or purple-blue legs, so that it looks as though it is wearing blue jeans. It is only one of many forms. On the islands of the Bocas del Toro archipelago in Panama and in scattered mainland populations the species appears in solid orange, bright yellow, lime green, white with black spots, deep red all over, and dull brown-black, among others. Several of these morphs occur within a very short distance of one another, which has made the species a well-known natural experiment in how colour and pattern evolve.
Are strawberry poison frogs dangerous to touch?
They are toxic but not in the league of the golden poison frog. The skin of a wild strawberry poison frog carries alkaloid compounds, taken up from its diet of ants and mites, that taste foul and cause pain, burning, swelling, and temporary numbness if they get into broken skin, the mouth, or the eyes. Healthy intact skin on your hand is a reasonable barrier for a brief moment of contact, but handling is still a bad idea, both because any small cut changes the picture and because the frog is extremely sensitive to salts, oils, and soap residues on human skin. Captive-bred frogs fed on crickets and fruit flies contain no poison at all, since the toxins come entirely from wild prey.
How does the mother frog raise her tadpoles?
It is one of the most involved forms of parental care in any frog. The female lays a small clutch of eggs in moist leaf litter, and the male keeps them damp by carrying water in his cloaca. When the eggs hatch, the female returns, and one tadpole at a time squirms onto her back and sticks there in a film of mucus. She then climbs, sometimes many metres up a tree, and slips that single tadpole into the tiny reservoir of rainwater trapped where a bromeliad leaf meets the stem. She distributes her tadpoles among several such pools so that no accident wipes out the whole brood. Because these pools contain almost nothing to eat, she comes back to each one every few days and deposits a batch of unfertilised eggs for the tadpole to eat, continuing until it completes metamorphosis.
What is the difference between a poison frog and a poison-dart frog?
They are the same thing. The family Dendrobatidae contains around 200 species of small, often vividly coloured, day-active frogs of Central and South America, and they are called poison frogs or poison-dart frogs more or less interchangeably. The dart part of the name comes from the practice of a few Indigenous groups in western Colombia, who used the skin secretions of three of the largest and most toxic species, in the genus Phyllobates, to poison blowgun darts for hunting. The great majority of the family, including the strawberry poison frog, were never used this way and range from mildly toxic to harmless, so poison frog is the more accurate general term.