Panamanian Golden Frog

Biologically it is a toad. It belongs to the family Bufonidae, the true toads, and to the genus Atelopus, the harlequin toads, a large group of slender, often brightly coloured, stream-dwelling Central and South American bufonids that have been hit exceptionally hard by the chytrid fungus. The common name "golden frog" stuck because the animal is slim and smooth-skinned and does not look like a typical warty toad. Whatever it is called, it is one of about a hundred Atelopus species, the great majority of which are now Critically Endangered, Extinct in the Wild, or Extinct.

It is a form of visual signalling that evolved because sound does not work in its habitat. Panamanian golden frogs live right beside torrential, boulder-strewn mountain streams whose roar masks the quiet clicks and trills the frogs can produce. To communicate over that noise, they use body language — a frog will raise one forelimb and rotate the hand and forearm in a slow, deliberate circle, a movement biologists call "semaphoring" or hand-waving, and it also flags its feet and bobs its head. Males wave to tell rival males to keep away from a territory and, in a gentler form, to court females. It is one of the clearest cases of a frog switching from acoustic to visual communication because of environmental noise.

Very. The skin of the Panamanian golden frog secretes a mix of toxins, the most notable being zetekitoxin AB, a compound unique to this species that blocks the voltage-gated sodium channels nerves use to fire. It is water-soluble (unlike the fat-soluble poison dart frog toxins) and extraordinarily potent — laboratory estimates put it well above tetrodotoxin, the pufferfish poison, in toxicity per unit weight, and there is no antivenom. In practice the frog is only dangerous if eaten or if the toxin enters a wound or the mouth or eyes; the bright yellow colour is an honest warning to predators. As with dart frogs, captive-bred golden frogs raised on a controlled diet are far less toxic or non-toxic, because part of the toxin arsenal is derived from wild prey.

Not yet, and this is the central problem. The species is being kept alive by a network of zoos and dedicated facilities in Panama and North America, notably the Panama Amphibian Rescue and Conservation Project and the Maryland Zoo, which hold biosecure "assurance colonies" and have learned to breed the frogs reliably. But the reason the frog disappeared — the amphibian chytrid fungus, Batrachochytrium dendrobatidis — is still present throughout its former range, and any frogs released now would almost certainly become infected and die. Research is focused on finding ways to give the frogs resistance, such as probiotic skin bacteria, selective breeding for tolerance, or controlling the fungus in release sites, before reintroduction can be attempted.