One species of underwater snail – Cone snails – are well known for their poisonous venom, and more than fifteen people have been killed because of it. That’s scary enough, but scientists have recently found that one particular of these snails – Conus geographus (The Geography Cone Snail) – doesn’t even need to release its venom.
Usually, to fill your prey with poison you’d need a claw, fang, or stinger, and the geography cone snail does have a tooth that it can use to inject venom into animals, but it can also just release venom straight into the water. The cocktail of toxins disorients the surrounding fish, enabling the snail to simply swallow them up.
The venom was found to be a more compact form of insulin than the kind humans and vertebrates use, which when injected into a fish, causes a fast and dangerous drop in blood glucose levels, usually called hypoglycemia, which stopped them from being able to swim properly. The researchers estimate that the snail could, if it wanted to, take out a whole school of fish with this insulin venom.