A peacock mantis shrimp is about the size of a cigar. It lives in a burrow on a coral reef, eats crabs and snails, and has been known to break aquarium glass. That last part is not an exaggeration. Researchers who keep them in captivity use special reinforced tanks, because a standard glass wall is not a serious obstacle to an animal that hits things for a living.

The mantis shrimp is not actually a shrimp. It belongs to an ancient order called Stomatopoda, which split from other crustaceans roughly 400 million years ago. In evolutionary terms, they have been doing their own thing for a very long time. And it shows.

Two Strategies, One Order

There are around 450 species of mantis shrimp, and they divide roughly into two groups based on how they kill things. Spearers have barbed appendages they use to impale soft-bodied prey. Fish, worms, shrimp that wander too close. Smashers have calcified clubs they use to bludgeon hard-shelled animals into pieces small enough to eat.

The peacock mantis shrimp (Odontodactylus scyllarus) is the most studied of the smashers, partly because it is strikingly beautiful. Electric blues, greens, and reds across its body. And partly because its punch has become something of a scientific obsession.

The Punch

The club of a peacock mantis shrimp accelerates at roughly 10,000 g and reaches speeds of around 70 miles per hour. The strike delivers approximately 1,500 newtons of force. Enough to crack the shell of a clam or the claw of a crab with a single blow. But the strike itself is only part of the story.

When the club moves that fast through water, it creates cavitation bubbles. Pockets of low pressure that collapse almost immediately and release a second shockwave. That secondary impact arrives milliseconds after the first. The prey gets hit twice from a single swing. During the collapse of those bubbles, the local temperature briefly spikes to somewhere in the range of 8,000 degrees Fahrenheit. Comparable to the surface of the sun. The bubbles exist for an instant, but they do real damage.

Engineers at UC Riverside studied the club’s structure and found it is built to absorb this kind of punishment without shattering. The helix-shaped fibers in the club redistribute stress in a way that prevents cracks from propagating. A design that has since influenced research into better helmets and body armor.

The Eyes

Mantis shrimp eyes get cited constantly in popular science articles, usually with some version of the claim that they “see 16 times more colors than humans.” The reality is more interesting and more complicated than that.

Humans have three types of photoreceptors. Mantis shrimp have sixteen. They can detect ultraviolet light, infrared light, and multiple channels of polarized light that are invisible to us. Their eyes move independently and can each focus on the same object simultaneously from different angles.

But a 2014 study published in Science found that mantis shrimp actually perform worse than humans on standard color discrimination tasks. Distinguishing between two similar shades of the same color, for example. Their visual system does not appear to work the way ours does. Rather than comparing signals between photoreceptors to build a nuanced color picture, they seem to process each channel independently, almost like a barcode scanner. Fast, parallel, efficient. But not the same as “seeing more.”

What they are doing with all that visual information is still not fully understood. Some of it likely involves rapid threat assessment. Some of it may be tied to communication. Mantis shrimp produce polarized light patterns on their bodies that are invisible to most other animals.

Social Life

Mantis shrimp are not particularly social in the way that term is usually meant, but they are more cognitively complex than their reputation as reef-dwelling wrecking balls suggests. They recognize individual neighbors. Distinguishing between animals they have encountered before and strangers. And adjust their behavior accordingly. A known neighbor poses a predictable threat; a stranger is a wild card. This kind of individual recognition requires memory and some capacity for discrimination that goes beyond simple stimulus-response.

Several species are also monogamous, with pairs sharing burrows for up to 20 years. They take turns foraging and guarding. By crustacean standards, that is a remarkably stable domestic arrangement.

Why They Matter

Mantis shrimp are predators on coral reefs, which means they help regulate populations of the hard-shelled invertebrates- urchins, crabs, mollusks, that can otherwise dominate reef ecosystems. They are also prey for larger fish, so they sit in the middle of a food web that keeps reefs functioning.

But the more lasting impact may be in materials science. The cavitation-resistant club, the polarized light communication, the multi-channel visual processing. Each of these has already generated real research with practical applications. For an animal most people have never heard of, the mantis shrimp has had an outsized influence on how engineers and neuroscientists think about structure, optics, and perception.

It helps that they will break your aquarium if you underestimate them.