Amphibians
Mantella
Mantella · also called mantellas, Malagasy poison frogs
A mantella looks exactly like a South American poison frog — 2 cm long, fire-orange or green-and-black, active in daylight, toxic skin — and it is not even distantly related to one. It lives only in Madagascar, evolved the whole package independently, and most of its 16 or so species are now sliding toward extinction as the island’s forests burn.
Overview
Mantellas are the genus Mantella, about 16 species, endemic to Madagascar, mostly in the eastern rainforest belt. They are tiny day-active insectivores of the forest floor, eating ants and mites, and they are a textbook case of convergent evolution with the unrelated poison frogs of the Americas — same size, colours, diet, toxins, and breeding behaviour, arrived at separately.
Borrowed toxins, borrowed look
Mantellas cannot make their own poison and sequester alkaloids from their ant-and-mite diet, so wild frogs are toxic and captive-bred ones are harmless. Colours range from the fire-orange golden mantella to cryptic browns. Eggs are laid on land in leaf litter or moss, and the tadpoles wash into streams, ponds, or water-filled leaf axils to develop.
Status
The genus is Endangered overall and one of the most threatened frog groups in the world — most species are threatened, and the golden mantella and Baron’s mantella are Critically Endangered or Endangered. The causes are the burning and clearing of Madagascar’s eastern rainforest for rice, pasture, and charcoal, plus mining and heavy pet-trade collection, acting on frogs that often occupy a single small forest fragment.
Mantella: common questions
Are mantellas the same as poison dart frogs?
No. They look almost identical and live almost identical lives, but they are not related and live on opposite sides of the world. Poison frogs, family Dendrobatidae, are found only in Central and South America. Mantellas, genus Mantella, are found only in Madagascar and belong to a completely different family, the Mantellidae, which is more closely related to certain Old World frogs. The strong resemblance, small brightly coloured bodies, daytime activity, ant-based diet, toxic skin, and elaborate breeding, is a textbook example of convergent evolution, where unrelated animals facing the same problems and opportunities arrive at the same solution independently.
Are mantellas poisonous?
Wild ones are, though far less dangerously than the golden poison frog of Colombia. A mantella's skin contains alkaloid toxins, chiefly pumiliotoxins and related compounds, that it does not manufacture but takes up from the ants and mites in its diet and concentrates in skin glands. These make the frog distasteful and mildly toxic to predators and can cause irritation and numbness if they get into a person's eyes or a cut, so wild mantellas should not be handled with bare hands. Captive-bred mantellas raised on fruit flies and other cultured insects never acquire the toxins and are completely harmless, which is one reason captive breeding is encouraged.
Why are so many mantellas endangered?
Two things combine. First, most mantella species have naturally tiny ranges, sometimes a single hillside or river valley, because Madagascar's forests are patchy and the frogs cannot disperse across open or dry ground. Second, those forests are disappearing fast, cleared and burned for rice paddies, cattle pasture, and charcoal, and degraded by mining and invasive plants. A species restricted to one forest fragment can be pushed to the edge of extinction by the loss of that single patch. On top of habitat loss, mantellas have been collected in large numbers for the international pet trade. The golden mantella, for instance, survives in only a handful of small swamp forests east of Antananarivo.
Can you keep a mantella as a pet?
Yes, and captive-bred mantellas of several species, especially the golden and the painted mantella, are available and make good display animals, being active and colourful by day and safe to keep since captive-bred frogs are non-toxic. They need a planted, humid, well-ventilated terrarium kept fairly cool, a steady supply of very small live insects such as flightless fruit flies and springtails, and clean water for any tadpoles. The important choice is to buy only captive-bred frogs from a reputable source, since wild-caught mantellas are taken from already threatened populations, often arrive stressed and parasitised, and are best left in the forest.