Venom is one of the animal kingdom's oldest and most effective weapons, providing creatures with an effective means of attack or defense. Spider venom, for example, is thought to have evolved from a single protein 375 million years ago, while snake venom first appeared 60 to 80 million years ago. Scientists have even identified a dinosaur from the early Cretaceous period (145 to 66 million years ago) that used venom to place its prey in a "rapid state of shock," according to a study published in 2009 .
Unlike poisonous animals, which have toxins that victims inhale, absorb or swallow, , venom is injected into the target. Venom has evolved multiple times across all animal groups, except birds, with its potency developing through a chemical arms race alongside the target's resistance to the venom. An estimated 15% of animals are venomous , from jellyfish the size of your fingernail through to giant lizards and snakes.
Here are 32 of the most venomous animals on Earth. Irukandji box jellyfish The Irukandji box jellyfish ( Carukia barnesi ) is a tiny species, growing to just 0.8 inch (2 centimeters) in diameter, yet its stinging tentacles, which can stretch up to 3.
2 feet (1 meter), can pack a very nasty punch. Its venom — which causes Irukandji syndrome — attacks the nervous system and can paralyze the lungs and heart. The jellyfish attack using the specialized stinging cells that line their four tentacles, firing venom-filled barbs at their target, according to the Australi.