Amphibians
European Fire-bellied Toad
Bombina bombina · also called European fire-bellied toad, fire-bellied toad, fire toad
The European fire-bellied toad keeps its warning where a predator will only see it too late. Grab this small grey pond-dweller and it throws its body into a sharp arch, turns up its feet, and flashes a belly of shocking orange and black — the unken reflex — while its skin foams a bitter toxin.
Overview
European fire-bellied toads live in warm, still, well-vegetated shallow water across lowland eastern and central Europe, from Denmark to the Black Sea. They are 4–5 cm, flat and warty, drab grey-brown above and brilliant orange-and-black below. They eat worms, insects, and molluscs, and males call from the water with a soft hooting.
The unken reflex
Cornered, the toad arches its spine, lifts its chin, and turns its palms and soles outward to display the hidden aposematic belly colours, sometimes flipping right over. The bluff is backed by real foaming skin secretions — bitter peptides and alkaloids that sting a predator’s mouth and eyes.
Small but very old
Despite its size, this toad regularly lives 15–20 years, and one captive individual reportedly reached 29 — remarkable for such a small amphibian.
Status
The European fire-bellied toad is Least Concern but declining in western and northern Europe with the loss of shallow, sunlit, fish-free ponds; it is legally protected across much of the EU.
European Fire-bellied Toad: common questions
What is the unken reflex?
It is a defensive display named from the German word Unke, meaning a fire-bellied toad. An animal doing the unken reflex bends its body into a sharp upward or backward arch, lifts its head, and folds its limbs up so the palms and soles face outward, revealing bright warning colours that are hidden when the animal is at rest. In the European fire-bellied toad the hidden colour is the vivid orange-and-black belly and the undersides of the limbs. The message to a predator is unmistakable — this animal is toxic and not worth eating — and it is backed up by real, foul-tasting skin secretions. Several unrelated amphibians, including some salamanders and other toads, have independently evolved the same posture.
Are fire-bellied toads poisonous to humans or pets?
They are mildly toxic and should be handled carefully, but they are not dangerous in the way a poison dart frog or a cane toad can be. The skin secretes irritant peptides and alkaloids that taste bitter and foul and can froth into a mild foam; this deters predators and, in a person, can sting badly if it gets into the eyes, nose, mouth, or a cut, and may cause skin irritation. The sensible precautions are to wash your hands before and after handling, keep the toad away from your face, and not house it with other amphibian species, whose skin is more sensitive to the toxins. A dog that mouths one will usually just drool and spit it out.
How is the European fire-bellied toad different from the oriental one sold in pet shops?
The fire-bellied toad most often kept as a pet is the oriental fire-bellied toad, Bombina orientalis, from northeastern China, Korea, and Russia, which typically has a brighter, more solidly green-and-black back and a red-and-black belly. The European fire-bellied toad, Bombina bombina, is a lowland eastern and central European species with a duller grey-brown, more blotched back and an orange-to-red belly. They are close relatives with similar behaviour — the unken reflex, aquatic males with a gentle hooting call, toxic skin — but the European species is more strictly tied to warm lowland ponds, is less often traded, and is a protected species across much of its range.
Why does the fire-bellied toad "hoot" instead of croak?
The male's advertisement call is a soft, melodious, rhythmic "oop... oop... oop," repeated steadily, quite unlike the harsh croak of a common toad or the trill of a natterjack. He calls while floating at the surface of a pond, and unusually he produces the sound as he breathes in rather than out, using a paired internal vocal sac. A chorus of many males on a warm spring or summer evening carries a gentle, bell-like or dove-like quality across the water. Females are drawn to the calls, and pairs mate in the water, with the male clasping the female around the waist rather than behind the front legs as most frogs do.