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Ocean Assassins: 5 of Nature's Coolest Underwater Weapons

Whether you’re a mammal, fish or cephalopod, you’d better be ready when the enemy attacks. Check out these five innovative underwater weapons.

It’s a jungle … er … an ocean out there! Whether you’re a mammal, a fish or a cephalopod, you’d better be ready when the enemy attacks. Or when you just get really hungry. Check out these five innovative underwater weapons from the aquatic killers.


1. The Blenny’s Bite

This adorable little fish may look harmless, but watch out for the venomous fangs! If a fang blenny is attacked, it turns on its assailant, sinking its fangs into flesh.

But why would a big, bad, ocean predator care about a couple of pinpricks? Scientists have just discovered they don’t. In fact, the blenny’s bite may keep them from caring about much of anything. It turns out that the venom doesn’t cause pain, but relieves it instead.




What’s in the blenny bite? Opium, of course. The opium injection causes a sudden drop in blood pressure, making the larger fish disoriented and unable to hunt while the little blenny gets away.

They’re so successful in turning around a seemingly impossible situation that nonvenomous blennies pretend to be their biting cousins by mimicking their colors and patterns. Because the larger fish don’t want to do drugs, the fang blenny wannabes are able to get close enough to snack on their scales. Yuuuummmmm!


2. Lethal Injection

This little snail predator specializes in insulin shots. As dinner swims by, Conus geographus and Conus tulipa, two types of cone snail, release insulin and neurotoxins into the water, dulling the sensory responses of nearby fish and causing hypoglycemia.

But snails like to linger over their seafood dinner. To make sure the stunned fish sticks around to be eaten, the snail surrounds it with its extended mouth, then paralyzes it with toxins so it can’t move while its eaten alive.

Bon appétit?


3. Killing With Air

Humpback whales are huge, weighing almost 70,000 pounds. But it’s not their brawn that brings them brunch — it’s their brains. A small pod can wreak carnage in a school of herring. And it’s only weapon? Air.




Humpbacks hunt together, casting wide nets of air bubbles that trap fish inside. Once there’s enough for everyone, the whales surface together with mouths wide open, scooping the fish inside.


4. DIY Stinging Tentacle Whip

The Portuguese man o’ war is known for its painful and sometimes fatal sting, but the blanket octopus is immune to its venom, which makes it a dangerous predator.



Not only is it able to use its own stretchy body to appear larger and to squirt intimidating ink; it also hunts down the Portuguese man o’ war, rips off its tentacles and uses them as stinging, whip-like weapons.


5. Aquatic Archery

Scientists have discovered that the archerfish has better aim than Legolas. Whether their target is inches or feet away, their shots always hit their prey at maximum impact.

It took four years for scientists Stefan Schuster and Peggy Gerullis to figure out how archerfish weaponize water. They concluded that it continually manipulates the shape of its mouth and the velocity of the water it expels. Technically, Schuster argues, this means fish use tools, too.

Take that, octopus!



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