The mantis shrimp is not your average shrimp. In fact, it's not a shrimp at all. It's a stomatopod crustacean only distantly related to the shrimp — and this stomatopod is deadly. The cigar-sized mantis shrimp packs a surprisingly big punch, with raptorial appendages and fierce muscles that can deliver a 60-mile-per-hour (96-kilometer-per-hour) blow that's strong enough to crush aquarium glass or smash a crab instantaneously. And, if defending itself, a mantis shrimp could cut through a human's finger within milliseconds — an injury that can lead to amputation. That's why marine biologist Katie Watson says it's best to keep your distance.
"Nicknamed the thumb splitter, they can cause painful injuries if they are not treated with care," Watson says in an email. "They can also shatter fins or a camera lens, so don't get too close, and as a fundamental rule of diving: look, but don't touch."
Muscle power is only one factor behind the mantis shrimp's ferocity. The crustacean has a system of biological springs, latches and levers that work in tandem to deliver piercing strikes. This is the fastest limb movement in the animal kingdom, says Watson.
While its power is impressive, the mantis shrimp boasts much more than brute strength. Here are seven mind-blowing facts about the mighty and marvelous mantis shrimp.
1. Mantis Shrimp Eyes Are a Scientific Wonder
The mantis shrimp, like all crustaceans, has compound eyes. But unlike fellow crustaceans — and every other living being — they have the most complex visual system in the world. With up to 16 photoreceptors and the ability to see UV, visible and polarized light, the mantis shrimp's eyes put our 20/20 vision to shame. They're the only animals known to see circularly polarized light, and they can see colors and images accessible to no other animal on Earth.
2. They Have Their Own Communication Code
A complex visual system is the mantis shrimp's key for communication. Since the crustaceans have the power to see and alter polarized light that other animals can't, they use this light manipulation to communicate — almost like a secret code. In research published in the journal Scientific Reports in 2016, researchers discovered that mantis shrimp polarizers alter light across a structure, not through its depth like typical polarizers. Most other creatures can't see this type of light, so those that use it are less likely to attract predators or those competing for food. This realization was more than just mind-blowing; scientists say it could lead to new optical human technologies across everything from cameras to sunglasses.
3. Mantis Shrimp Also "Speak" Through Rumbles
At dawn and dusk, mantis shrimp make rumbling growl and grunt sounds to defend their territory and attract mates. Researchers describe this as a low-frequency rumbling that's created via muscle vibrations. Fellow mantis shrimp "hear" these rumbles through sensory body hairs. So far, scientists have only witnessed males producing sound; analyzed females didn't make a peep.
4. Their Colors Can Glow Like a Retro Lite Brite
Mantis shrimp colors run the gamut, from browns to vibrant reds, blues and greens. Some species are even biofluorescent, a trait that lets the crustacean absorb blue light as it hits their bodies, then re-emit it as a different color. "The wavelengths of their fluorescent coloration travels better underwater than color pigmentation," Watson says. "The fluorescence increases the apparent size of the mantis shrimp which helps attracts females during mates and warns off competitive males." This illumination may also attract prey, but Watson notes research to prove the phenomenon is ongoing.
5. You'll Rarely See Mantis Shrimp at Aquariums
In 2001, two mantis shrimp sneakily made their way into the Monterey Bay Aquarium by hitchhiking on imported rocks. The result was like a sci-fi thriller. Crabs, snails and barnacles essential to the aquarium ecosystem and filtration went missing. But the aquarium couldn't put its workers at risk trying to catch the mantis shrimp barehanded. Instead, they had metal tongs at the ready to grab it when exposed, then place it with another mantis shrimp they snagged the year prior.
This is not an uncommon scene when mantis shrimp sneak into aquariums. That's why the crustacean is rarely kept in captivity. When they are, aquariums need shatterproof acrylic glass and a tank free of critters given their threatening traits.
6. But You May Find Them in Tropical Waters
Except, the chance of actually seeing the sneaky mantis shrimp in person is pretty tricky. Mantis shrimp are remarkable hiders. They spend most of their time tucked away in rocky and sandy burrows. Mantis shrimp prefer shallow marine waters, mostly in tropical and subtropical regions. They can also live in coral reefs or rock crevices. This habitat is ideal hunting grounds. The mantis shrimp stays tucked away until prey gets close, then boom — it strikes, instantly kills and feasts, all in mere seconds.
7. Mantis Shrimp Are Threatened by Climate Change
Earth's warming oceans threaten nearly all sea life, and the mantis shrimp isn't spared. "Calcified marine organisms [like the mantis shrimp] face a double-edged sword as climate change is projected to increase ocean warming and acidification," Watson says. "This is predicted to result in increased energy demands, growth restriction, physiological stress and changes in mineralization. For mantis shrimp to maintain the integrity of their highly specialized weapon appendage, precise mineral composition and mechanical properties in different layers of exoskeleton are needed."
Watson says some research indicates mantis shrimp can tolerate long-term increases in temperature and acidification, but the degradation of coral reefs paired with overfishing could affect them just like other reef dwellers: lost habitat and decreased vertebrate and invertebrate diversity.