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

amphibian Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...

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 t ...

, toads, and certain species of

frogs A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order Anura (coming from the Ancient Greek , literally 'without tail'). Frog species with rough skin texture due to ...

. 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 Substituted tryptamine, tryptamines of which some are toxic. They occur in the parotoid glands, skin, and poison of many toads (True toad, Bufonidae family) and other amphibians, an ...

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 in biology, advertising by an animal, whether terrestrial or marine, to potential predation, predators that it is not worth attacking or eating. This unprofitability may consist of any defenses which make the pr ...

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

References

{{Signalling theory Signalling theory Antipredator adaptations

See also

References