"Beautiful" and "deadly" are two descriptors you don’t typically see attached to shrimp. But the mantis shrimp is in a class of its own. This colorful specimen has earned a reputation for being one of the most fearsome creatures of the deep. Here are 10 facts worth knowing about the pint-sized bruisers.
1. Mantis shrimp aren't actually shrimp.
2. They pack a powerful punch.
The peacock mantis shrimp (Odontodactylus scyllarus) uses two appendages called dactyl clubs to pummel prey like aquatic Rock 'Em Sock 'Em Robots—that is, if kids’ toys could punch fast enough to boil water and split fingers to the bone. These wrecking ball "fists" spring forth from their bodies at 50 mph, accelerating quicker than a .22-caliber bullet. At those speeds, the water surrounding them briefly reaches the temperature of the Sun’s surface. When the dactyl clubs hit their target, they deliver 160 pounds of force, smashing through shells like a lightning-fast crab mallet.
3. There are hundreds of species of mantis shrimp.
Mantis shrimp come in a variety of species, and we’re aware of about 550 of them. Stomatopods from different species range in size from smaller than an inch to longer than a foot. They’re usually classified by murder method—either smashing, as detailed above, or spearing. In place of dactyl clubs, spearers have two sharp appendages on the front of their bodies built for harpooning prey. Spear-wielding mantis shrimp don’t move as fast as their club-fisted counterparts (their strikes are about 10 times slower), but the threat of death by impalement is intimidating on its own.
4. Their vision is unparalleled.
Peacock mantis shrimp have the most complex set of peepers in the animal kingdom. Each eye contains 12 photoreceptors that allow them to sense different types of color. For comparison, human eyes typically contain three types of light-sensitive cells for seeing red, blue, and green. This has led some to conclude that mantis shrimp perceive the world in a psychedelic rainbow of vibrant color we can’t begin to comprehend. But in reality, the crustaceans are actually worse at differentiating between subtle variations in hue than we are.
A study from the University of Queensland found that when mantis shrimp were shown colors with a difference in wavelength less than 25 nanometers, they had trouble telling them apart. But just because mantis shrimp may not see the variations between powder blue and periwinkle doesn’t mean their vision isn’t extraordinary. On the contrary, their optic abilities are on a completely separate level from ours, functioning more like a satellite than anything found in nature. Scientists believe that mantis shrimp take all the visual information they see into their brains at once without processing it, allowing them to react to their surroundings as quickly as possible. Their independently roaming eyes and trinocular vision also make them excellent hunters.
5. They share a secret language.
In addition to the all epic abilities listed above, mantis shrimp are one of the only creatures capable of seeing polarized light. This has allowed them to develop a secret code that’s undetectable to other species. The Haptosquilla trispinosa species of mantis shrimp wields feathery feeding appendages called maxillipeds that are marked with iridescent, blue spots. The cells of these features reflect light in a unique way. Instead of bouncing light into a reflective structure like the polarizing cells developed by humans, the cells distribute light across the spot’s surface. The brilliant light is plainly visible to other mantis shrimp, allowing them to signal members of their species while staying hidden from predators.
6. You won't find mantis shrimp in most aquariums.
You’d think a mantis shrimp’s technicolor exterior would make it a staple at most aquariums, but this creature is rarely kept in captivity. The same dactyl clubs that allow them to shatter shellfish are also capable of cracking a glass tank. When aquariums do accept a ruthless specimen into their collection, it must kept behind shatterproof acrylic glass. On top of that, a captive mantis shrimp needs to be the sole occupant of its specially constructed home, lest it decides to treat its tank-mates as punching bags.
7. They make menacing sounds.
It’s only natural that a creature as ferocious as the stomatopod would have a threatening call to match. California mantis shrimp have been known to make low, rumbling growling sounds both in the wild and the lab. Male mantis shrimp often emit grunts at dawn and dusk, the periods of the day when they’re most likely to be hunting for food or guarding their homes. Scientists theorize that the growls are meant to attract mates and ward off competitors.
8. Mantis shrimp are helping scientists build better body armor.
The mantis shrimp’s super-powered punching abilities raise a puzzling question: How can the animal deliver such a deadly blow without injuring itself? To get to the bottom of the mystery, researchers looked at the composition of the peacock mantis shrimp’s built-in weaponry. They found that the creature’s dactyl clubs consisted of an outer coating of hydroxyapatite, a hard crystalline calcium-phosphate ceramic material. Beneath the surface lies the key to the animal’s anti-fracturing qualities. Layers of elastic polysaccharide chitin underlying the shell are positioned in a way to act as shock absorbers, reducing the possibility of cracks. The design is so effective that researchers modeled a type of carbon fiber material after it with potential applications in aircraft panels and military body armor.
9. They practice social monogamy.
The life of a mantis shrimp isn’t all cold-blooded killing. Some species of stomatopods are known to engage in the rare practice of social monogamy, a behavior that’s especially remarkable among crustaceans. This means mantis shrimp will choose one partner to share food, shelter, and raise offspring with over the course of a lifetime.
What may sound romantic to humans serves a practical purpose for mantis shrimp: Research has shown that certain mantis shrimp tend to cluster outside reefs instead of living in the heart of the action. Without the need to go looking for someone new to mate with on a regular basis, mantis shrimp couples are able to enjoy a relatively safe, sedentary lifestyle secluded from predators.
10. They're older than dinosaurs.
Stomatopods began evolving independently from other crustaceans nearly 400 million years ago, about 170 million years before the first dinosaurs appeared on the scene. Since then they’ve followed an isolated, evolutionary lineage that’s resulted in some of their more unique characteristics. Their biology is so bizarre that scientists have assigned them the nickname "shrimp from Mars."
This article was originally published in 2016; it has been updated for 2022.