Many people call a snake ‘poisonous’ when they mean venomous’. The latter involves injecting prey with a toxin (venom), whereas the former is secreting a defensive toxin (poison) that an attacker would prefer not to touch.
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Are any snakes poisonous?
Just two groups of snakes are known to be poisonous. North American garter snakes appear to acquire toxins when they eat newts, at least temporarily.
Asia’s keelback snakes also obtain toxins from prey, this time toads, but retain the noxious chemicals in special glands in their neck.
This has been known for a while, but recently scientists discovered a twist in the tale. One species, the groove-necked keelback of China and Vietnam, feeds on earthworms instead of toads, yet still boasts the unpleasant deterrent.
Earthworms don’t possess toxins, so where is this snake getting them? The researchers found it supplements its wormy diet with firefly larvae, which, like toads, manufacture the deadly substances it needs.
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Main image: Speckle-belly keelback © Getty
