Bathysquilloidea Gonodactyloidea Erythrosquilloidea Lysiosquilloidea Squilloidea Eurysquilloidea Parasquilloidea Mantis shrimps are carnivorous marine crustaceans of the order Stomatopoda (from Ancient Greek στόμα (stóma) 'mouth' and ποδός (podós) 'foot').

Stomatopods branched off from other members of the class Malacostraca around 400 million years ago,[2] with more than 520 extant species of mantis shrimp known.

[4] Dubbed "sea locusts" by ancient Assyrians, "prawn killers" in Australia,[5] and now sometimes referred to as "thumb splitters" due to their ability to inflict painful wounds if handled incautiously,[6] mantis shrimp possess powerful raptorial appendages that are used to attack and kill prey either by spearing, stunning, or dismembering; the shape of these appendages are often used to classify them into groups: extant mantis shrimp either have appendages which form heavily mineralized "clubs" that can strike with great power, or they have sharp, grasping forelimbs used to swiftly seize prey (similar to those of praying mantis, hence their common name).

Mantis shrimp are commonly separated into distinct groups (most are categorized as either spearers or smashers but there are some outliers)[9] as determined by the type of claws they possess: 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.

[15] The collapse of these cavitation bubbles produces measurable forces on their prey in addition to the instantaneous forces of 1,500 newtons that are caused by the impact of the appendage against the striking surface, which means that the prey is hit twice by a single strike; first by the claw and then by the collapsing cavitation bubbles that immediately follow.

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.

[20] Each eye consists of two flattened hemispheres separated by parallel rows of specialised ommatidia, collectively called the midband.

[23] Cheroske et al. did not observe spectral tuning in Neogonodactylus oerstedii, the species with the most monotonous natural photic environment.

The diversity of spectral tuning in Stomatopoda is also hypothesised to be directly linked to mutations in the retinal binding pocket of the opsin.

Over the years, some mantis shrimp species have lost the ancestral phenotype, although some still maintain 16 distinct photoreceptors and four light filters.

[clarification needed] It is suggested that not discriminating between closely positioned wavelengths allows these organisms to make determinations of its surroundings with little processing delay.

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.

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.

By combining different techniques, including movements in the same direction, the midband can cover a very wide range of the visual field.

[44] 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.

[45] The eyes of mantis shrimps 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.

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.

Stomatopods of the species Haptosquilla trispinosa were able to distinguish high and low-saturation colors from grey, contravening Thoen and colleagues.

[49] 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.

[citation needed] Mantis shrimp can be diurnal, nocturnal, or crepuscular (active at twilight), depending on the species.

Stomatopod body size undergoes periodic growth which necessitates finding a new cavity or burrow that will fit the animal's new diameter.

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).

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.

In Japanese cuisine, the mantis shrimp species Oratosquilla oratoria, called shako (蝦蛄), is eaten boiled as a sushi topping, and occasionally raw as sashimi.

The shrimp can be steamed, boiled, grilled, or dried, used with pepper, salt and lime, fish sauce and tamarind, or fennel.

[citation needed] 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.

While some aquarists value mantis shrimps, others consider them harmful pests, because they are voracious predators, eating other desirable inhabitants of the tank.