In an ancient story that appears in several religions, the prophet Jonah survived three days inside a whale before being spat out. Of course, surviving being eaten in real life is impossible.
Or is it? Through clever adaptations there are animals that can pass through a predator’s digestive system and emerge unscathed.
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Some snails, such as a tiny land species called Tornatellides boeningi, can withstand being eaten by birds. Researchers in Japan noticed them still alive in bird faeces and experimented to prove that a reasonable proportion of them survived the digestive process.
Their small size helped, and possibly a mucus secreted by the snails that protects them from digestive juices by covering their shell openings.
In a curious evolutionary twist, it’s thought being swallowed actually helps the species spread, as some snails gave birth after the ordeal, having been pooed out of the bird in a new location.
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The Brahminy blind snake, a non-venomous species found in Africa and Asia, is often mistaken by predators for a worm.
Live snakes have been observed emerging from an owl pellet, having slithered round the stomach, aided by the fact that birds have very fast digestive processes.
They can also survive being eaten by some frogs that are designed to digest worms but cannot cope with snake scales, and so they pass through unharmed.
Rough-skinned newts, along with some other animals that excrete toxins through their skin, can survive being taken into a predator’s mouth but rarely make it as far as the stomach, let alone the intestines.
They generally poison the aggressor and are either forcibly ejected in vomit or walk their way back out when the animal is dead.
A tightly closed mussel can be ingested by an anemone and live. The indigestible shell is eventually rejected, complete with unhurt owner. But any tiny crack in the shell, or a defective hinge, and the anemone will find a way to inject its digestive fluid – and that’s the end of the mussel.
There are online tales of snake eels digging themselves out of their predator’s stomachs with the sharp tips of their tails used for burrowing in the seafloor.
However, only a handful of examples of living eels turning up on fishmongers’ slabs have been recorded. Most eels that make it out of the predator’s stomach are trapped by the ribcage and become mummified in the fish’s body cavity.
Top image: the jaws of an American crocodile. Credit: Troy Harrison/Getty Images
