Unkenreflex – interchangeably referred to as unken reflex (''Unke'' is the German word for the genus of fire-bellied toads) – is a defensive posture adopted by several branches of the amphibian class – including

salamanders Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All ten ...

toads Toad is a common name for certain frogs, especially of the family Bufonidae, that are characterized by dry, leathery skin, short legs, and large bumps covering the parotoid glands. A distinction between frogs and toads is not made in scienti ...

, and certain species of

frogs A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil "proto-frog" '' Triadobatrachus'' is ...

. Implemented most often in the face of an imminent attack by a predator, unkenreflex is characterized by the subject’s contortion or arching of its body to reveal previously hidden bright colors of the ventral side, tail, or inner limb; the subject remains immobile while in unkenreflex. During the course of unkenreflex, the amphibian in question releases

bufotoxin Bufotoxins are a family of toxic steroid lactones or substituted tryptamines of which some may or may not be toxic. They occur in the parotoid glands, skin, and poison of many toads ( genus ''Bufo'') and other amphibians, and in some plants and ...

s from its parotid glands, tenses its entire body, and swallows air to bloat itself in an attempt to look larger. These secretions, along with the

aposematic Aposematism is the advertising by an animal to potential predators that it is not worth attacking or eating. This unprofitability may consist of any defences which make the prey difficult to kill and eat, such as toxicity, venom, foul taste o ...

coloring common among the amphibians which display unkenreflex, serve as a warning to nearby predators that the amphibian may be poisonous. Not all amphibians which display unkenreflexes possess aposematic coloring, nor do all amphibians display unkenreflex to the same degree. Certain species of anurans, such as the adult male ''

Rana macrocnemis The long-legged wood frog (''Rana macrocnemis''), also known as Caucasus frog, Brusa frog, or Uludağ frog, is a species of frog in the family Ranidae found in Armenia, Azerbaijan, Georgia, Iran, Russia, Turkey, and Turkmenistan. Its natural h ...

'', only half-complete unkenreflex (also called low-intensity, or partial unken reflex) by only twisting its body slightly and not revealing the entire underside coloring, or by shielding their face with raised feet that have dramatic coloration, or by curling their tail and exposing the tail's underside. This half completion of unkenreflex can be found both in species that display aposematic coloring and those that do not; unkenreflex is not entirely limited to poisonous amphibians. This behavior is named after the

fire-bellied toad fire-bellied toads are a group of six species of small frogs (most species typically no longer than ) belonging to the genus ''Bombina''. The name "fire-bellied" is derived from the brightly colored red- or yellow-and-black patterns on the toa ...

(German: '' Unke''; combining form: ''Unken-'') which exhibits this reflex.

References

{{evo ecol Antipredator adaptations

See also

References