blue ringed octopus

Venomous Ocean Animals

By Kathy Kranking

“Nobody bothers me!” That’s what the ocean animals in this story might say.

Tap image for a closer view.

And they’d be mostly right! Other creatures usually steer clear of the animals you’re about to meet. That’s because they all have a secret weapon: venom. Venom is a kind of poison that comes from an animal’s bite or sting. It can hurt, paralyze, or even kill. Venom isn’t foolproof, though, because some animals aren’t bothered by some kinds of venom. But if you’re not big and strong, don’t have teeth and claws, or aren’t very quick, venom can come in pretty handy! These animals all use venom to defend themselves from predators, and many use it to catch prey, as well. Keep reading to meet them up close—but not too close!


This lionfish looks pretty, with its “mane” of fancy fins. But those fins hold a hidden danger. Inside each of them is a long, venomous spine. If anything tries to attack the lionfish—zap!—the spines deliver a painful sting.

Tap image for a closer view.


This soft, squishy Spanish shawl nudibranch (NOO-duhbrank) looks like an easy meal to slurp up. But the nudibranch has a clever trick to protect itself. It “steals” stingers from its prey!

Here’s how it works: The nudibranch eats anemones and other small stinging creatures. The stingers don’t bother the nudibranch. Instead, they travel through its body and out to the tips of those pointy orange things on its back. Then, if a predator attacks the nudibranch, it gets stung by the stolen stingers!


The blue-ringed octopus is only about the size of a golf ball. But it packs a big punch! This octopus actually has two kinds of venom in its saliva (suh-LYE-vuh), or spit. It uses the weaker kind to paralyze prey when it bites with its beak. It saves the other, deadlier, kind to use against predators.

Predators do get a warning, though. When the octopus feels threatened, it flashes bright blue circles that appear on its body. It’s as if it’s wearing a neon sign that says, “Mess with me, and you’ll be sorry!”


The box jellyfish swims slowly along through the ocean, looking graceful and harmless. But its long, trailing tentacles aren’t harmless at all. They’re lined with tiny, super-venomous stingers. The jellyfish uses the stingers to catch prey. It will also sting predators that attack it. Most animals avoid it, but a few, such as sea turtles, aren’t bothered by the stingers.

Tap image for a closer view.


A stonefish lies still as a stone on the ocean floor. Its colorful, bumpy skin helps disguise it as coral or algae (AL-jee). Soon, a small fish or other unsuspecting animal will come near. Then the stonefish will suck the prey into its mouth and swallow it whole.

But the stonefish has protection from becoming prey itself. On its back are spines that can inject venom into an attacker that might try to take a bite. Only a few predators, such as large sharks, are not bothered by the venom.


The sea krait (KRAYT) is a venomous snake that swims in the ocean near coral reefs and islands. It sometimes comes ashore to rest awhile on rocks or sand. The krait has sharp fangs that shoot venom as it bites prey such as eels. The venom also protects it from most enemies that would dare to attack it.


The cone snail might look as if it had a tiny trunk. But that’s its proboscis (proh-BAH-sis) poking out from its shell. The snail uses the proboscis to sniff the water to find prey. Then it shoots out a tiny harpoon from its mouth, which is below the proboscis. The harpoon shoots venom into the prey.

And if an enemy comes along? The snail uses the harpoon to shoot even stronger venom into the enemy!


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