Mantis Shrimp

The mantis shrimp's second pair of thoracic appendages is adapted for powerful close-range combat. These claws can accelerate at a rate comparable to that of a .22 caliber bullet when fired, having around 1500 newtons of force with each swing/attack. The appendage differences divide mantis shrimp into two main types: those that hunt by impaling their prey with spear-like structures and those that smash prey with a powerful blow from a heavily mineralised club-like appendage. A considerable amount of damage can be inflicted after impact with these robust, hammer-like claws. This club is further divided into three subregions: the impact region, the periodic region, and the striated region. Mantis shrimp are commonly separated into distinct groups (most are categorized as either spearers or smashers but there are some outliers) as determined by the type of claws they possess: * Spearers are armed with spiny appendages - the spines having barbed tips - used to stab and snag prey. These raptorial appendages resemble those of mantises, hence the common name of these crustaceans. This is the type found in most mantis shrimp. * 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 prey 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. This is found in the families Gonodactylidae, Odontodactylidae, Protosquillidae, and Takuidae. * Hatchet: An unusual, highly derived appendage that only a few species have. This body plan is largely unresearched. (raptorial claw, ballistic claw) of mantis shrimp]] 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. In smashers, these two weapons are employed with blinding quickness, with an acceleration of 10,400 g (102,000 m/s2 or 335,000 ft/s2) and speeds of 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. Even if the initial strike misses the prey, the resulting shock wave can be enough to stun or kill. The collapsing bubbles also produce light, which is termed sonoluminescence. 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 and cephalopods, which their barbed claws can more easily slice and snag. The appendages are being studied as a microscale analogue for new macroscale material structures.

showing the structure of the eyes. The three dark spots are pseudopupils, indicating the ommatidia that are pointing towards the camera's POV]] eyes]] The eyes of the mantis shrimp are mounted on mobile stalks and can move independently of each other. The extreme mobility allows them to be rotated in all three dimensions, yet the position of their eyes has shown to have little effect on the perception of their surroundings. Mantis shrimp are thought to have the most complex eyes in the animal kingdom and the most complex front-end for any visual system ever discovered. Each compound eye is made up of tens of thousands of ommatidia, clusters of photoreceptor cells. This phenomenon, called "spectral tuning", is species-specific. Cheroske et al, did not observe spectral tuning in Neogonodactylus oerstedii, the species with the most monotonous natural photic environment. In N. bredini, a species with a variety of habitats ranging from a depth of 5 to 10 m (although it can be found down to 20 m below the surface), spectral tuning was observed, but the ability to alter wavelengths of maximum absorbance was not as pronounced as in N. wennerae, a species with much higher ecological/photic habitat diversity. The diversity of spectral tuning in Stomatopoda is also hypothesised to be directly linked to mutations in the retinal binding pocket of the opsin. The huge diversity seen in mantis shrimp photoreceptors likely comes from ancient gene duplication events. One consequence of this duplication is the lack of correlation between opsin transcript number and physiologically expressed photoreceptors. Mantis shrimp can perceive wavelengths of light ranging from deep ultraviolet (300 nm) to far-red (720 nm) and polarised light. In mantis shrimp in the superfamilies Gonodactyloidea, Lysiosquilloidea, and Hemisquilloidea, the midband is made up of six ommatidial rows. Rows 1 to 4 process colours, while rows 5 and 6 detect circularly or linearly polarised light. Twelve types of photoreceptor cells are in rows 1 to 4, four of which detect ultraviolet light. Despite the impressive range of wavelengths that mantis shrimp have the ability to see, they do not have the ability to discriminate wavelengths less than 25 nm apart. It is suggested that not discriminating between closely positioned wavelengths allows these organisms to make determinations of its surroundings with little processing delay. Having little delay in evaluating surroundings is important for mantis shrimp, since they are territorial and frequently in combat. ]] Their UV vision can detect five different frequency bands in the deep ultraviolet. To do this, they use two photoreceptors in combination with four different colour filters. They are currently believed to be insensitive to infrared light. The optical elements in these rows have eight different classes of visual pigments and the rhabdom (area of eye that absorbs light from a single direction) is divided into three different pigmented layers (tiers), each for different wavelengths. The three tiers in rows 2 and 3 are separated by colour filters (intrarhabdomal filters) that can be divided into four distinct classes, with two classes in each row. Each consists of a tier, a colour filter of one class, another tier, a colour filter of another class, and then a last tier. These colour filters allow the mantis shrimp to see with diverse colour vision. Without the filters, the pigments themselves make up only a small segment of the visual spectrum, from about 490 to 550 nm. Rows 5 and 6 are also segregated into different tiers, but have only one class of visual pigment, the ninth class, and are specialised for polarisation vision. A tenth class of visual pigment is found in the upper and lower hemispheres of the eye.) and four for analysing polarised light. By comparison, most humans have only four visual pigments, of which three are dedicated to seeing colour, and human lenses block ultraviolet light. The visual information leaving the retina seems to be processed into numerous parallel data streams leading into the brain, greatly reducing the analytical requirements at higher levels. The midband covers only about 5 to 10° of the visual field at any given instant, but like most crustaceans, mantis shrimps' eyes are mounted on stalks. In mantis shrimp, the movement of the stalked eye is unusually free, and can be driven up to 70° in all possible axes of movement by eight eyecup muscles divided into six functional groups. By using these muscles to scan the surroundings with the midband, they can add information about forms, shapes, and landscape, which cannot be detected by the upper and lower hemispheres of the eyes. They can also track moving objects using large, rapid eye movements where the two eyes move independently.

Six species of mantis shrimp have been reported to be able to detect circularly polarised light, which has not been documented in any other animal. They perform this feat by converting circularly polarized light into linearly polarized light via quarter-waveplates formed from stacks of microvilli. Some of their biological quarter-waveplates perform more uniformly over the visual spectrum than any current man-made polarising optics, and this could inspire new types of optical media that would outperform early 21st century Blu-ray Disc technology. The species Gonodactylus smithii is the only organism known to simultaneously detect the four linear and two circular polarisation components required to measure all four Stokes parameters, which yield a full description of polarisation. It is thus believed to have optimal polarisation vision. It is the only animal known to have dynamic polarisation vision. This is achieved by rotational eye movements to maximise the polarisation contrast between the object in focus and its background. Since each eye moves independently from the other, it creates two separate streams of visual information.

]] What advantage sensitivity to polarisation confers is unclear; however, polarisation vision is used by other animals for sexual signaling and secret communication that avoids the attention of predators. This mechanism could provide an evolutionary advantage; it only requires small changes to the cell in the eye and could easily lead to natural selection. The eyes of mantis shrimp may enable them to recognise different types of coral, prey species (which are often transparent or semitransparent), or predators, such as barracuda, which have shimmering scales. Alternatively, the manner in which they hunt (very rapid movements of the claws) may require very accurate ranging information, which would require accurate depth perception. The capacity to see UV light may enable observation of otherwise hard-to-detect prey on coral reefs. Females are fertile only during certain phases of the tidal cycle; the ability to perceive the phase of the moon may, therefore, help prevent wasted mating efforts. It may also give these shrimps information about the size of the tide, which is important to species living in shallow water near the shore. Researchers suspect that the broader variety of photoreceptors in the eyes of mantis shrimp allows visual information to be preprocessed by the eyes instead of the brain, which would otherwise have to be larger to deal with the complex task of opponent process colour perception used by other species, thus requiring more time and energy. While the eyes themselves are complex and not yet fully understood, the principle of the system appears to be simple. It has a similar set of sensitivities to the human visual system, but works in the opposite manner. In the human brain, the inferior temporal cortex has a huge number of colour-specific neurons, which process visual impulses from the eyes to extract colour information. The mantis shrimp instead uses the different types of photoreceptors in its eyes to perform the same function as the human brain neurons, resulting in a hardwired and more efficient system for an animal that requires rapid colour identification. Humans have fewer types of photoreceptors, but more colour-tuned neurons, while mantis shrimp appear to have fewer colour neurons and more classes of photoreceptors. However, a study from 2022 failed to find unequivocal evidence for a solely "barcode"-like visual system as described above. Stomatopods of the species Haptosquilla trispinosa were able to distinguish high and low-saturation colors from grey, contravening Thoen and colleagues.

at Wakatobi National Park Sulawesi, partially out of its burrow]] Mantis shrimp are long-lived and exhibit complex behaviour, such as ritualised fighting, or by the use of fluorescent patterns on their bodies for signalling with their own and perhaps even other species. Many have developed complex social behaviours to defend their space from rivals; mantis shrimp are typically solitary sea creatures that may aggressively defend their burrows, either rock formations or self-dug intricate burrows in the seabed. They are rarely seen outside their homes except to feed and relocate. They can learn and remember well, and are able to recognise neighbouring mantis shrimp with which they frequently interact. They can recognise them by visual signs and even by individual smell. Mantis shrimp can be diurnal, nocturnal, or crepuscular (active at twilight), depending on the species. Unlike most crustaceans, they sometimes hunt, chase, and kill prey. Although some live in temperate seas, most species live in tropical and subtropical waters in the Indian and Pacific Oceans, encompassing the seas between eastern Africa and Hawaii. Mantis shrimp live in burrows where they spend the majority of their time. The spearing species build their habitat in soft sediments and the smashing species make burrows in hard substrata, such as cavities in coral. These two habitats are crucial for their ecology since they use burrows as sites for retreat and as locations for consuming their prey. In the monogamous species, the mantis shrimp 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. Although stomatopods typically display the standard types of movement seen in true shrimp and lobsters, one species, Nannosquilla decemspinosa, has been observed rolling itself into a crude wheel (somewhat resembling volvation). The species lives in shallow, sandy areas. At low tides, N. decemspinosa 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 thus performs a forward flip in an attempt to roll towards the nearest tide pool. N. has been observed to roll repeatedly for , but specimens typically travel less than .

=== Evolutionary history === , a primitive Carboniferous mantis shrimp]] Although the Devonian Eopteridae have been suggested to be early stomatopods, their fragmentary known remains make the referral uncertain. The oldest members of Unipeltata date to the Triassic.

* Family Gonodactylidae ** Gonodactylus smithii * Family Hemisquillidae ** Hemisquilla ensigera ** Hemisquilla australiensis ** Hemisquilla braziliensis ** Hemisquilla californiensis * Family Lysiosquillidae ** Lysiosquillina maculata, zebra mantis shrimp or striped mantis shrimp * Family Nannosquillidae ** Nannosquilla decemspinosa ** Platysquilla eusebia * Family Odontodactylidae ** Odontodactylus scyllarus, peacock mantis shrimp ** Odontodactylus latirostris, pink-eared mantis shrimp ** Odontodactylus brevirostris * Family Pseudosquillidae ** Pseudosquilla ciliata, common mantis shrimp * Family Squillidae ** ** Rissoides desmaresti ** Squilla empusa ** Squilla mantis * Family Tetrasquillidae ** Heterosquilla tricarinata, New Zealand File:Austrosquilla osculans 61399682.jpg|Austrosquilla osculans File:Specimen of Bathysquilla crassispinosa.JPG|Bathysquilla crassispinosa, museum specimen File:Gonodactylus platysoma.jpg|Gonodactylus platysoma File:Kasim philippinensis (MNHN-IU-2014-23089) 001.jpeg|Kasim philippinensis, museum specimen File:Mantis shrimp.jpg|Lysiosquillina maculata File:Mantis Shrimp Sole and Eel - Lysiosquillina maculata (cropped).jpg|Lysiosquillina maculata outside its burrow File:Pullosquilla thomassini (10.3897-zookeys.721.20588) Figure 4.jpg|Pullosquilla thomassini File:Squilla mantis.jpg|Squilla mantis File:Vossquilla kempi (10.1590-2358-2936e2017012) Figure 3 (cropped).jpg|Vossquilla kempi A large number of mantis shrimp species were first scientifically described by one carcinologist, Raymond B. Manning; the collection of stomatopods he amassed is the largest in the world, covering 90% of the known species whilst 10% are still unknown.

, Thanh Hóa, Vietnam]] The mantis shrimp is eaten by a variety of cultures. In Japanese cuisine, the mantis shrimp species Oratosquilla oratoria, called , is eaten boiled as a sushi topping, and occasionally raw as sashimi. Mantis shrimp are also abundant along Vietnam's coast, known in Vietnamese as bề bề, tôm tích or tôm tít. In regions such as Nha Trang, they are called bàn chải, named for its resemblance to a scrub brush. The shrimp can be steamed, boiled, grilled, or dried, used with pepper, salt and lime, fish sauce and tamarind, or fennel. , Việt Nam]] In Cantonese cuisine, the mantis shrimp is known as "urinating shrimp" () because of their tendency to shoot a jet of water when picked up. After cooking, their flesh is closer to that of lobsters than that of shrimp, and like lobsters, their shells are quite hard and require some pressure to crack. One common preparation is first deep-frying, then stir-frying with garlic and chili peppers. They may also be boiled or steamed. In the Mediterranean countries, the mantis shrimp Squilla mantis is a common seafood, especially on the Adriatic coasts (canocchia) and the Gulf of Cádiz (galera). In the Philippines, the mantis shrimp is known as tatampal, hipong-dapa, pitik-pitik, or alupihang-dagat, and is cooked and eaten like any other shrimp. In Kiribati, mantis shrimp called te waro in Gilbertese are abundant and are eaten boiled. In Hawaii, some mantis shrimp have grown unusually large in the contaminated water of the Grand Ala Wai Canal in Waikiki. The dangers normally associated with consuming seafood caught in contaminated waters are present in these mantis shrimp.

in an aquarium]] Some saltwater aquarists keep stomatopods in captivity. The peacock mantis is especially colourful and desired in the trade. While some aquarists value mantis shrimp, others consider them harmful pests, because they are voracious predators, eating other desirable inhabitants of the tank. Additionally, some rock-burrowing species can do more damage to live rock than the fishkeeper would prefer. The live rock with mantis shrimp burrows is considered useful by some in the marine aquarium trade and is often collected. A piece of live rock not uncommonly conveys a live mantis shrimp into an aquarium. Once inside the tank, it may feed on fish and other inhabitants, and is notoriously difficult to catch when established in a well-stocked tank. While there are accounts of this shrimp breaking glass tanks, they are rare and are usually the result of the shrimp being kept in too small a tank. While stomatopods do not eat coral, smashers can damage it if they try to make a home within it.