Green-and-black Poison Frog

It is genuinely toxic but well below the level of the golden poison frog. Its skin secretes pumiliotoxins and related compounds that cause pain, cramps, and, in a large enough dose, effects on the heart and nervous system of an animal that bites it. A predator that mouths one is quickly deterred and learns to avoid the pattern, which is the point of the bold colouring. For a person, the risk comes from handling a wild frog and then touching the eyes, mouth, or a cut — the toxins are absorbed through membranes and broken skin, not intact skin — so wild frogs should not be handled. It cannot poison you simply by being in the same room, and it is not capable of a fatal envenomation the way the golden poison frog is.

Because the frog does not manufacture its own poison. It sequesters alkaloid toxins from the tiny ants and mites it eats in the wild and concentrates them in glands in its skin. Remove that dietary source — as happens in a terrarium, where the frogs are fed fruit flies and pinhead crickets — and the frog has nothing to build the toxins from, so captive-bred individuals are completely non-toxic and safe to handle gently. This is true of all poison dart frogs and is why the pet trade in them is possible at all. It also means a wild frog gradually loses potency if its food supply of alkaloid-rich prey declines.

Parental care in this species is mainly the male's job. A female lays a small clutch of eggs in leaf litter or another sheltered spot on the ground, and the male returns periodically to moisten and guard them. When the tadpoles hatch, the male backs into the clutch, lets one or a few wriggle onto his back where they stick to a mucous coating, and then climbs — sometimes several metres — to deposit each tadpole in a separate small pool of water trapped in a tree hole, a curled leaf, or the centre of a bromeliad. Spreading the tadpoles among many nurseries means a single predator or a pool drying out cannot destroy the whole brood. The tadpoles then develop on their own, eating detritus and insect larvae.

In 1932, about 200 green-and-black poison frogs were deliberately brought from the Taboga Islands of Panama and released on Oahu as a biological control agent, in the hope that they would eat mosquitoes and other pest insects. As a mosquito-control measure it failed — the frogs eat mostly ants and mites and had little effect. But the frogs themselves survived and bred, and a small, self-sustaining population persists in the wet forested valleys behind Honolulu, especially around Manoa. Hawaii has no native amphibians, and while these frogs are not considered a major invasive threat, they are one of several introduced amphibians now established on the islands.