Sea Slugs Can Arm Themselves with Venom from Other Animals?!

These nudibranchs (sea slugs) are lit up like the midway at a county fair because they’re warning predators that they use stinging cells called nematocysts to defend themselves when attacked. But the nematocysts are not native to nudibranch physiology — they hoover them up from hydroids, a jellyfish relative, and distribute them around their bodies.

The nudibranch’s gut has fingerlike branches that extend up into the long cerata on its back. The unfired stingers travel up into the cerata and concentrate in little sacs at the tips, where they continue to develop.

If a fish or crab tries to bite the nudibranch, it squeezes those sacs and shoots out the stingers, which immediately pop in the predator’s mouth. It doesn’t take long for predators to avoid the brightly colored nudibranchs.

What a wild adaptation! (via the kid should see this)

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