Sea snails: the ocean's pirates
The toughest underwater animals? That has to be the nudibranchs! They are a formidable enemy to jellyfish and sea anemones because - unlike others - they are not deterred by their tentacles and venom. What is worse, the snails even use that venom to their own advantage. Sea anemones cannot get out of the way quickly when an enemy approaches them. They therefore rely on their tentacles full of poisonous stinging cells. Jellyfish are also armed with these. These stinging cells are like a small capsule with a coiled, hollow thread inside: a poisonous 'harpoon'. Upon a stimulus (e.g. a touch), the thread shoots out with great force and pierces the prey. The poison then released can paralyse or kill the prey. This punishing method of protection keeps almost all sea predators at bay. Almost all, because some nudibranchs are resistant to the venom.
Dinner first
Nudibranchia or nudibranchs, like their counterparts on land, have no shell. Yet they often have an impressive appearance, courtesy of their vibrant hues - from cheerful purple, through bright blue to fluorescent orange. But don't let that frivolous appearance fool you. Some nudibranchs are feared pirates, hunting - without flinching - the jellyfish and anemones feared by other pirates, and devouring them - nettle cells and all. How the snail manages to eat the nettle cells without being bothered by them? Pellets are released from the cells in the front part of their digestive system. These form a protective layer, allowing the snail to continue nibbling happily.
Then steal
Since the marine nudibranch is "homeless" and cannot retreat into its home for defence, the mollusc decides not to simply digest the nettle cells but put them to useful use. The snail does this by storing the harpoons in special pouches. Is she in danger in the future? Then she simply fires the stolen nettle cells - as if the weapon was always hers.