Mantis Shrimp: Characteristics, Smashers and Spearers | Sea Life, Islands and Oceania

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MANTIS SHRIMP

mantis shrimp (Odontodactylus scyllarus)

Mantis shrimp are considered the strongest pound for pound punchers. Some species are among the most colorful shrimp. They come in a variety of specular psychedelic colors. One is aptly named the peacock shrimp. They also have very acute sight when it come to color. Tiny and unique-looking mantis shrimp are voracious predators in their larval and adult phases. They are feared by the fishermen community.There come in two varieties — spearers and smashers, which describe how they attack their prey.

Mantis shrimp are carnivorous marine crustaceans of the order Stomatopoda. They are regarded as “living fossils” as they branched off from other members of the class Malacostraca (which includes crabs, lobsters and krill) around 340 million years ago. Today they are found in tropical and subtropical coastal waters around the world. Although some live in temperate seas, most species live in tropical and subtropical waters in the Indian and Pacific Oceans between eastern Africa and Hawaii.

There are more than 450 species of mantis shrimp known. They range in color from shades of brown to vivid colours, They typically grow to around 10 centimeters (3.9 inches). The biggest ones can reach up to 38 centimeters (15 inches) They are among the most important predators in many shallow, tropical and subtropical marine habitats. Despite being common, they are poorly understood, as many species spend most of their lives sheltering in burrows and holes. [Source: Wikipedia]

Alice Clement wrote: They are fearsome marine carnivores known to deliver a dizzyingly fast and painful blow, with the fastest self-powered strike in the animal kingdom. They also live a colourful life. During mating season they fluoresce (emit light) and have complex eyes to watch these displays. In fact, they have up to 16 colour receptors, whereas humans have just three..They belong to the suborder Unipeltata, which appeared some 190 million years ago. [Source: Alice Clement, Research Associate in the College of Science and Engineering, Flinders University, The Conversation October 10, 2022]

Websites and Resources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Fishbase fishbase.se ; Encyclopedia of Life eol.org ; Smithsonian Oceans Portal ocean.si.edu/ocean-life-ecosystems

Mantis Shrimp Characteristics

peacock mantis shrimp (Odontodactylus scyllarus)

A mantis shrimp's carapace (the hard, thick shell of a a crustacean) covers only the rear part of the head and the first four segments of the thorax. Attached to the abdomen's middle line are several pairs of pleopods, maxillepeds or swimmerets used for swimming, which also have special filaments and gills for respiration. Some mantis shrimp species have specialised calcified 'clubs' that can strike with great power, while others have sharp forelimbs used to seize the prey (hence the term "mantis" in their common name).

Mantis shrimp possess the most complex eyes in nature. They rotate separately 180 degrees like a chameleon and provide superb spatial perception. They also provide extraordinary “trinocular vision" using visual receptors in three distinct bands and 16 different kinds of light-sensing retinal cells, including four for ultraviolet lights and polarized light. In contrast humans have only four kinds of retinal cell types and can not see ultraviolet or polarized light. In addition, mantis shrimp are believed to have eight cone types in their eyes for detecting color will most fish have four.

Mantis shrimp eyes process much of the information they receive before it even reaches the brain, reducing the work load on the brain. Each tiny dome on the surface of the shrimp’s eye is a separate cornea that admits light. The cornea connects to a crystalline cone and photoreceptors called a rhabdon. The most specialized light processing occurs in the middle photoreceptors. These give detailed readings from available light.

Mantis Shrimp Behavior

Mantis shrimp can be aggressive but are typically solitary sea creatures spend most of their time hiding in rock formations or burrowing intricate passageways in the sea bed. They rarely exit their homes except to feed and relocate, and can be active during the day, nocturnal, or crepuscular (active at twilight), depending on the species. Unlike most crustaceans, they sometimes stalk, hunt and chase prey. They feed on fish, shrimps, krill, marine worms, snails and other mantis shrimp. Sometimes they'll eat crabs or hermit crabs. It is not unusual for them to kill animals biger than themselves. [Source: Wikipedia]

eyes of mantis shrimp (Odontodactylus scyllarus)

Mantis shrimp are long-lived and exhibit complex behavior, such as ritualised fighting. Some species use fluorescent patterns on their bodies for signalling with their own and maybe even other species. They can learn and remember well, and are able to recognise individual neighbours with which they frequently interact. They can recognise them by visual signs and even by individual smell. Many have developed complex social behaviours to defend their space from rivals.

Although mantis shrimp typically display the standard types of movement seen in true shrimp and lobsters, one species, Nannosquilla decemspinosa, has been observed flipping itself into a crude wheel. The species lives in shallow, sandy areas. At low tides, it is often stranded by its short rear legs, which are sufficient for movement when the body is supported by water, but not on dry land. The mantis shrimp then performs a forward flip in an attempt to roll towards the next tide pool. This shrimp has been observed rolling repeatedly for two meters (6.6 feet), but usually doesn’t travel more than one m (3.3 feet).

Mantis Shrimp Smashers and Spearers

The two main categories of mantis shrimp — spearers and smashers — favour different locations for burrowing. The spearing species build their habitat in soft sediments and the smashing species make burrows in hard substrata or coral cavities. A few species have a primitive appendage called a hatchet. Spike Smashers (hammers or primitive smashers): possibly the "missing link" to relate the two most common (spear and smasher) to each other. They are very uncommon.

Smashers possess a much more developed club and a more rudimentary spear (which is nevertheless quite sharp and still used in fights between their own kind); the club is used to bludgeon and smash their meals apart. The inner aspect of the terminal portion of the appendage can also possess a sharp edge, used to cut prey while the mantis shrimp swims. Spearers are armed with spiny appendages — the spines having barbed tips — used to stab and snag prey. [Source: Wikipedia]

Both types strike by rapidly unfolding and swinging their raptorial claws at the prey, and can inflict serious damage on victims significantly greater in size than themselves. Smashers use this ability to attack crabs, snails, rock oysters, and other molluscs, their blunt clubs enabling them to crack the shells of their prey into pieces. Spearers, however, prefer the meat of softer animals, such as fish, which their barbed claws can more easily slice and snag.

Mantis Shrimp Smashers

range of mantis shrimp (Odontodactylus scyllarus)

According to the Washington Post: “The title of fastest punch in the animal kingdom firmly belongs to the peacock mantis shrimp, whose club-like appendages reach the speed of a .22-caliber slug, shatter clamshells with ease and can slice human fingers to the bone.”

Smashers employ their club-like weapons with blinding quickness — with an acceleration of 10,400 g (102,000 meters per second squared or 335,000 feet per second squared. and speeds of 23 mters per second (83 kilometers per hour, 51 mph) from a standing start. Because they strike so rapidly, they generate vapor-filled bubbles in the water between the appendage and the striking surface—known as cavitation bubbles. The collapse of these cavitation bubbles produces measurable forces on their prey in addition to the blows themselves, whose instantaneous forces have been measured to be 1,500 newtons. This means that prey is hit twice — first by the claw blow and then by the collapsing cavitation bubbles that immediately follow. Even if the initial strike misses the prey, the resulting shock wave can be enough to stun or kill. [Source: Wikipedia]

Mantis shrimp are able to throw deadly blows just nine days after birth according to research, published in the Journal of Experimental Biology by researchers who looked at the larvae of several different species of mantis shrimp. According to to BGR: Mantis shrimp are capable of their incredible feats of fisticuffs thanks to a spring-like mechanism built into their front legs. The exoskeleton of the shrimp actually deforms, holding stored energy and then releasing it like a rubber band all at once as soon as the shrimp decides it’s time to go hands-on. Because of the transparent nature of especially young mantis shrimp, the researchers were able to study this mechanism in great detail. [Source: Mike Wehner, BGR, May 2, 2021]

“In studying the tiny shrimp, the authors of the paper reveal that juvenile mantis shrimp as small as a grain of rice possess the same punching ability as their parents. Because the baby shrimp are smaller but use a similar spring mechanism in their legs, you’d think that they might punch even faster, but with less overall force, when compared to the adults. That doesn’t seem to be the case, and the research team offers a few guesses as to why that might be. “Theoretically, they should be producing the highest acceleration but we don’t find that,” Jacob Harrison of Duke University, lead author of the work, said in a statement. “There are limitations to these spring and latch structures that we don’t fully understand, but whenever biology moves away from theoretical models it highlights some pretty interesting areas for us to learn.”

“One possibility is that water resistance is simply too strong to overcome for the smaller shrimp, reducing the speed at which they punch. Another theory is that the shrimp’s spring-actuated punching power is enhanced as it grows due to chances in its exoskeleton or other parts.

Mantis Shrimp Spearers

Spearers have specialized claws that fold up like knife blades. Lethal to marine life and dangerous to humans, they are strong enough to break glass and flip out in fraction of a second to spear or smash fish, crabs or rival mantis shrimp. One biologist told National Geographic, "I had a letter from a South African surgeon who picked one up while diving. His finger was so badly mangled that they had to amputated."

One spearer species has a first pair of leg-like maxillepeds near the mouth that are slender, hairy, and used for cleaning. The second pair of maxillepeds has relatively large lethal jackknifr-shaped claws. The shrimp uses these as spears to capture prey. The third, fourth and fifth set of maxillepeds are small legs that end in a flat oval shape called chelone. The chelone is used to bring food into the mouth. The last three pairs long and slender and are used as walking legs.

These mantis shrimp spear or slice through their prey in a quick slashing motion. After immobilizing their prey they drag it into their burrows to eat. According to Animal Diversity Web (ADW): The sharp claw is assisted by 6 spines found at the last joint. Their strike is one of the fastest movements known in the animal kingdom, reaching a velocity of 10 meters per second. It takes them less then 8 milliseconds to strike, which is about 50 times faster than the blink of an eye. A millisecond is equal to a millionth of a second. These claws are strong enough to dig through sand, rocks and even lacerate a hand, which is why they are also known as "thumb splitters", "finger poppers", "killer shrimp" and "thumb busters".

According to the Hilton Head Island Packet: They can be found along coastal shores, usually living in an abandoned burrow, sometimes U-shaped and move in and out to capture nearby prey when spotted. According to the Great Barrier Reef Foundation. “They have a unique set of “thumb splitters” or small appendages that they use to break or crack open shells of other crustaceans to retrieve food and nutrients. They are the fastest known organism due to their quick jabbing appendages that can reach up to 170 miles per hour,” according to Lamar University. [Source: Sarah Claire McDonald, Hilton Head Island Packet, July 8, 2022]

Mantis Shrimp Reproduction and Development

According to Animal Diversity Web: In males, the testes form a pair of delicate tubules that attach to sperm ducts that open at the penis, which is a modified long, slender, structure found at the base of the last pair of legs. The female ovaries form a broad mid band in the animals thoracic/abdomen region and the oviducts open at the middle of the 6th maximelleped . The eggs are developed and carried by the anterior legs, making it look as if the mother was eating her babies. [Source: Katherine Yi, Animal Diversity Web (ADW)]

According to graduate student Jennifer Wortham from the University of Lafayette, Stomatopod mating behavior varies considerably with each species, ranging from monogamous relationships to "promiscuous systems". Wortham's research deals mainly with mating strategies of successful males and the importance of their burrows as sexual resource. The larvae differ from the parents and they must go through several stages of metamorphosis before reaching an adult state. However, the metamorphic stages are not well known because they are hard to identify, "they seem to mature by developing their thoracic limbs, degenerating them, and then reforming them again.

In a lifetime, mantis shrimp can have as many as 20 or 30 breeding episodes. Depending on the species, the eggs can be laid and kept in a burrow, or they can be carried around under the female's tail until they hatch. Also depending on the species, males and females may come together only to mate, or they may bond in monogamous, long-term relationships.

In the monogamous species, the mantis shrimps remain with the same partner up to 20 years. They share the same burrow and may be able to coordinate their activities. Both sexes often take care of the eggs (bi-parental care). In Pullosquilla and some species in Nannosquilla, the female lays two clutches of eggs – one that the male tends and one that the female tends. In other species, the female looks after the eggs while the male hunts for both of them. After the eggs hatch, the offspring may spend up to three months as plankton.

Image Sources: Wikimedia Commons, NOAA

Text Sources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.

Last Updated April 2023