Mantis shrimp

Common Name:

Mantis shrimp

Scientific Name:

Stomatopoda

Type:

Invertebrates

Diet:

Carnivore

Size:

Up to 16 inches long

Weight:

Around 1.5 pounds

What are mantis shrimp?

Despite their name, mantis shrimp are not true shrimp but a type of stomatopod: a relative of crabs and lobsters that has been on Earth for over 400 million years. There are more than 400 different species of mantis shrimp.

Peacock mantis shrimp—also called harlequin or painted mantis shrimp—are arguably the best-known of the family. These critters get their name from their kaleidoscope shell—like a peacock’s tail—and their hinged forearms which resemble that of a praying mantis and are kept tucked away until the moment of attack. These solitary, aggressive animals are famous for their ferocious punch—as fast as a bullet and strong enough to snap a crab’s claw.

Habitat and appearance

Mantis shrimp live in warm, shallow waters in the Indian and Pacific oceans. To build a home, they use their raptor-like front arm to dig burrows on the seabed surrounding a coral reef. When they move on, other marine animals may take up residence in the abandoned burrow.

Growing to around the length of a butter knife, peacock mantis shrimp have rainbow shells—usually blue, green, and yellow—and red legs. Their purple eyes sit on top of stalks above their head and can move independently of one other for a better view.

(Learn about the peacock mantis shrimp with your kids.)

Not all mantis shrimp boast these spectacular colors. Zebra mantis shrimp—the largest of all the species—are named for their cream and brown stripes, while Red Sea mantis shrimp are beige with thin red stripes and a dark rear end.

But all these animals are best known for their mighty front claws—responsible for their impressive hunting skills.

Hunting and punching

Mantis shrimp are small but impressive predators that can kill prey bigger than themselves. Depending on the species, mantis shrimp use one of two hunting strategies: “Spearer” species lay in wait then skewer unsuspecting fish by using a large spike at the end of their arms. Meanwhile “smashers” like the peacock mantis shrimp use their hammer-like claws to attack their hard-shelled prey—such as crabs and clams—with a powerful punch.

So how does that punch work? When not in use, the shrimp’s clubbed arm is fastened securely in place by a latch, allowing energy to build up. A saddle-shaped spring within the arm helps store even more energy. When the latch is released, the spring propels the animal’s claw forward in the fraction of a second—50 times faster than we can blink—to hit their prey. At 75 feet per second, it is one of the fastest limb movements of any animal.

The strike is so fast—the speed of a .22 caliber bullet—that it causes bubbles to form and collapse in the water. This energy release creates an impressive force thousands of times the shrimp’s bodyweight that combines with the initial strike to smash open the shell of a mantis shrimp’s prey, killing the animal inside.

Remarkably, mantis shrimp are unharmed by the blow thanks to complex layers within the club which absorb the impact and prevent the claw from cracking. This innovative design has inspired the development of materials for armor, sports helmets, and vehicles.

Mantis shrimp use the same technique to defend themselves from predators. However, they only use this energy-intensive method of self-defense if they must. When under threat, they perform a behavioral display known as a meral spread before resorting to violence: standing on their hind legs, puffing up their chest, and spreading their arms to look as large and intimidating as possible. If the predator isn’t put off by this display, the shrimp will attack.

Superior vision

These crustaceans have among the most complex eyes in the animal kingdom. Their eyes work both independently and together so they can scan the horizon as well as focus in on prey. Each eye has three focal points, allowing the animal to perceive depth with either eye.

Human eyes have three photoreceptors—cells that detect color—to distinguish between blue, green, and red light. With a staggering 12 photoreceptors, mantis shrimp can see 12 different wavelengths of light. Strangely, however, they are worse at detecting subtle color differences than humans so it’s not clear what purpose these photoreceptors serve.

(How mantis shrimp send secret messages using twisted light.)

Unlike humans, mantis shrimp can see UV light and polarized light, which is made up of waves, and are the only animal known to detect circularly polarized light, which travels in a spiral. Researchers suspect this ability could allow them to communicate by displaying patterns on their shells that are visible to other mantis shrimp but not other ocean creatures. This might help them attract a mate or indicate that their burrow is already occupied.

Reproduction

When they’re ready to mate, mantis shrimp leave the safety of their burrow and zigzag across the sand until they find a partner. The female will store the male’s sperm until she is ready to spawn.

After laying her eggs, the female glues them together with a sticky substance secreted from a cement gland on her abdomen, gathers them up, and carries them into her burrow to look after them until they hatch. The young larvae can deliver the species’ famed punch after around nine days.

While not all species are monogamous, zebra mantis shrimp can live together in their burrow for life. But, with the male responsible for all the hunting, the female could starve to death if he is killed while out looking for food, or if he abandons her for a larger female who can produce more eggs.

Threats to survival

Like other reef species, mantis shrimp are likely affected by warming sea temperatures, ocean acidification, habitat destruction, and pollution. They are preyed on by large fish, cuttlefish, squid, and octopus.

Peacock mantis shrimp are popular among aquarium enthusiasts but can be difficult to keep in captivity because they often eat other species and can break glass tanks with their claws.

Although it is possible for humans to eat mantis shrimp—they are considered a delicacy in Asian countries—it’s not common because they put up such a fight.