Mantis sea shrimp (Odontodactylus scyallarus). stomatopods

• Class: Crustacea = Crustaceans, crayfish
• Subclass: Malacostraca = Higher crayfish
• Order: Stomatopoda = Stomatopods, mantis shrimp
• Family: Odontodactylidae = Mantis shrimp
• Species: Odontodactylus scyllarus = Peacock mantis shrimp or mantis shrimp (Peacock Mantis shrimp)

Species: Odontodactylus scyllarus = Mantis shrimp (Peacock Mantis shrimp)

• Read more: Mantis shrimp

Mantis shrimp Peacock or mantis shrimp is a very beautiful crustacean. But the male mantis shrimp have a very bright appearance. The eyes literally ripple from the variety of colors that adorn their covers. And not without reason, because these shrimp have a unique vision and probably the most complex eyes among all the animals on our planet. Features of their visual perception allow them to see objects in almost all ranges of the spectrum, which other animals are not capable of. And yet, they have the most complex eye structure.

The mantis shrimp is a very heat-loving animal, so its habitat is located in the Barrier Reef off the coast of Australia. They are found at various depths, but on average the optimum lies at a depth of 40 meters. Mantis shrimp make their home in makeshift sandy burrows or among coral debris. The length of these holes can reach 1 meter, going to a depth of up to 40 centimeters. Shrimps try to strengthen the walls of their dwelling by covering them with pieces of shells and pieces of coral.

Mantis shrimp have a bright color, but only males can boast of the most exquisite coloring. Their chitinous cover shimmers with all the colors of the rainbow. Their body is bright green, their head is blue, their forelimbs and antennae are bright red or orange. But the females are not so brightly colored and they are not so colorful. Most often, females are painted in calmer colors and have a brown or olive color of their integuments.

In length, mantis shrimp can reach 30 centimeters. Their body is laterally flattened and elongated. They got their name "praying mantis" for the ability to instantly throw out their forelimbs while hunting prey swimming nearby. The same technique is used by the mantis insect during the extraction of food but on land. Special observations have shown that such a strike from a praying mantis takes only 100 milliseconds, and this is comparable to one blink of an eye. But the strike of the mantis shrimp is already 50 times faster! Apparently, this is the fastest movement that animals are capable of.

The most formidable weapon of the mantis shrimp is the second pair of jaws, which are covered with razor-sharp spikes. They mercilessly pierce the victim's body blow after blow. This does not leave her a chance to stay alive. Therefore, mantis shrimp are also called fighting crayfish, terrorist crayfish or fighters. In this way they protect themselves from enemies, of which there are many, and earn their livelihood. Our fighters prefer to feast on fish, other shrimp, cuttlefish, marine polychaete worms, as well as mollusks and crayfish. Their unclenching tail helps them to carry out swift attacks, which throws them forward like a catapult.

But the most amazing organ of the mantis shrimp is still its eyes. They have a spherical shape and are divided in the center by parallel lines. But the main thing is that they are able to perceive and transform polarized light, which people cannot do. They see not only linear polarized light, but also circularly polarized light. And they can convert the first to the second, and vice versa. In addition, shrimp are able to see in the optical, infrared and ultraviolet ranges of the spectrum. This is what helps them to recognize the fluorescent marks on the body of other shrimp as danger signals or as threat signals to each other.

Very little is known about reproduction. When keeping these crustaceans in aquariums, it was often necessary to observe females with egg laying on their abdomens, but no one was lucky enough to see juveniles ...

Mantis shrimp, or mantis shrimp, belongs to the group of marine crustaceans. There are about 400 species of mantis shrimp that inhabit the shallow subtropical and tropical waters of the Indian and Pacific Oceans. Mantis shrimp spend most of their lives hidden in rocks and burrows at the bottom of the sea. They have colorful shells and body postures that resemble those of a praying mantis. Mantis shrimp are consumed as a delicacy mainly in Asian and Mediterranean countries. Because of their attractive morphology, Mantis shrimp are often collected from the wild and kept in private aquariums. Despite these factors, they are still abundant in the wild. Mantis shrimp are not on the endangered species list.

Interesting Mantis Shrimp Facts:

Mantis shrimp are typically 2 to 7 inches long. Large species grow up to 12 inches long.

Mantis shrimp are brightly colored. The shell of most species is covered in various shades of blue, green, red and orange. The forearms are often spotted.

The eyes of the mantis shrimp are located on long stalks that can move independently. They have exceptional vision, which is used both to detect prey and to identify possible predators in a timely manner.

Mantis shrimp have the most complex eyes in the animal kingdom, which can see ultraviolet and polarized light. They have trinocular vision, which means they can see one object using one of three different parts of the eye.

All Mantis shrimp can be classified into spearmen and strikers based on the morphology of the appendages and the tactics they use to kill prey.

Spearmen have spiny appendages that are used to strike at soft forms such as various types of worms and fish.

The "strikers" have round hard appendages that easily break the shell of snails, oysters, crustaceans and mollusks.

The Mantis shrimp attack is very fast - 50 times faster than the blink of an eye. At a speed of 10 meters per second, their impact has the power of a 0.22 caliber bullet.

"Strikers" are known for their incredibly strong impacts, which can break the glass of an aquarium.

Most species of mantis shrimp are solitary and territorial creatures. They desperately protect their home from intruders.

The males of this shrimp are able to recognize their neighbors due to smell and morphological characteristics.

Some species of mantis shrimp are monogamous and spend up to 20 years together. During mating rituals, shrimp mantises often fluoresce.

Females may lay their eggs in burrows or hold them in their front paws until they hatch. Some species show parental care. The female lays two sets of eggs, one for her and one for the father to take care of the eggs until they hatch.

Shrimp larvae swim in the water as part of marine zooplankton for up to 3 months. They exhibit aggressive behavior even at the larval stage.

The Mantis shrimp can live for over 20 years in the wild.

Description

The body of the stomatopods is large (from 10 to 34 cm long) and is divided into the following sections (or tagmas): protocephalon, jaw-thorax - from fused three jaw and four thoracic segments, chest - from four free segments and a powerfully developed segmented abdomen. The first pair of thoracic legs is sensory, the second to fifth pairs are grasping, and the last three pairs are walking. On the 1st-5th pairs of pectoral legs there are gills. The prehensile legs have an unusual feature: the last segment in them is sharp, serrated, blade-like and inserted into the longitudinal furrow of the penultimate segment like a penknife. The first pair of grasping legs is the largest, they grab the prey, and the rest of the grasping legs hold it. According to the structure of prehensile legs, stomatopods are similar to praying mantis insects, which was the reason for their name.

The abdominal region is longer than the anterior part of the body. The first five ventral legs are biramous, leaf-shaped, with pinnate setae. The functions of the anterior abdominal legs are very diverse. Thanks to their strokes, stomatopods swim. In addition, on all the anterior abdominal legs there are gills, which look like thin-walled, multiply branching appendages. The first two pairs of ventral legs in males are modified into a copulatory apparatus. The last pair of ventral legs are flattened. Together with the telson, they form the caudal fin. development with metamorphosis.

Vision

Mantis shrimp have one of the most complex visual systems ever studied. While humans have three types of color-sensitive cones in their eyes, mantis shrimp have 16. What's more, mantis shrimp can adjust the sensitivity of their long-wavelength vision to adapt to their environment. This phenomenon, known as "spectral tuning", is expressed differently in different species. Cheroske and colleagues found no spectral tuning in Neogonodactylus oerstedii, a species that lives in the most evenly lit environment. At N. bredini, a species that lives in various environments with a depth of 5 to 10 m (occasionally up to 20 m), spectral tuning is fixed, but its ability to change the length of the most felt wavelength is not as pronounced as in N. wennerae, the species with the greatest ecological and luminal diversity of habitats.

The middle strip of the eye consists of six rows of specialized ommatidia - rosettes of light-sensitive cells. Four rows contain up to 16 different pigments: 12 of them are sensitive to color, and the rest are used as color filters. The vision of mantis shrimp perceives both polarized light and multispectral images. Their eyes (mounted on independent movable stalks) are themselves multicolored and are considered the most complex eyes of the animal kingdom.

Each compound eye contains up to 10,000 adjacent ommatidia. The eye consists of 2 flattened hemispheres separated by 6 parallel rows of specialized ommatidia, collectively referred to as the "median stripe". Thus, the eye is divided into three regions. This allows the mantis shrimp to see objects with three different parts of the eye. In other words, each eye has trinocular vision and depth perception. The upper and lower hemispheres are primarily used to distinguish between shapes and movement, as are the eyes of many other crustaceans.

Rows 1-4 of the middle band are specialized in color perception, from ultraviolet to longer wavelengths. Their ultraviolet vision picks up five different wavelengths in the far UV range. For this, two photoreceptors are used in combination with four different color filters. There is currently no evidence for the ability of mantis shrimp to see infrared light. The optical elements in these rows include 8 different classes of visual pigments, and the rhabdom (the area of ​​the eye that receives light from one direction) is divided into three different pigment layers (tiers), each for its own wavelength. The three tiers in rows 2 and 3 are separated by color filters (interabdominal filters), which can be assigned to 4 distinct classes, two classes in each row. The design resembles a sandwich: a tier, a color filter of one class, another tier, a color filter of another class, and finally another tier. These color filters allow mantis shrimp to see many colors. Without filters, pigments perceive only a small fraction of the color spectrum: approximately 490-550 nm. Rows 5-6 are also divided into different tiers, but have only one class of visual pigment (ninth) and specialize in polarized light. They register different planes of polarization. The tenth class of visual pigments is found only in the upper and lower hemispheres of the eye.

The middle band covers only 5-10 degrees of the field of view, but, like most crustaceans, the eyes of mantis shrimp are fixed on stalks. The eye movements of mantis shrimp are unusually free along any axis - up to 70 degrees - thanks to 8 independent eye muscles, combined into 6 groups. With the help of this musculature, the mantis shrimp scans the environment through the middle lane, collecting information about shapes, silhouettes, and terrain that is inaccessible to the upper and lower hemispheres of the eye. They can also follow moving objects using sharp, sweeping eye movements performed by both eyes independently. Through a combination of these various techniques, including moving in the same direction, the middle lane can cover a significant portion of the field of view.

Some species have at least 16 types of photoreceptors, divided into four classes (the spectrum they perceive is also refined by color filters in the retina), 12 of which are designed for color analysis at various wavelengths (including six sensitive to ultraviolet), and four for analysis polarized light. For comparison, most people have only four visual pigments, of which three distinguish colors, and ultraviolet light is blocked by the cornea. At the exit from the retina, visual information is converted into many parallel data channels leading to the central nervous system, which significantly reduces the need for further processing.

At least two species have been found to be able to perceive circularly polarized light. Some of their biological quarter-wave plates work more reliably across the entire visual spectrum than any current artificial polarizers and suggest they could inspire a new type of optical media more efficient than the current generation of Blu-ray.

Type of mantis shrimp Gonodactylus smithii is the only organism known to be able to perceive the four linear and two circular polarization components needed to obtain all four Stokes parameters that completely describe the polarization. Hence, they have optimal polarization vision.

The vast variety of photoreceptor arrangements in mantis shrimp most likely arose from gene duplication sometime in the past. A curious consequence of this duplication is a discrepancy between the number of opsin transcripts and physiologically presented photoreceptors. One species can have 6 different opsin genes, but only one spectral type of photoreceptor is represented. Over time, mantis shrimp have lost their original phenotype, although some still have 16 different photoreceptors and 4 light filters. Species that live in different light environments experience selection pressure to maintain photoreceptor diversity and retain their original phenotype better than species that live in murky waters or are predominantly nocturnal.

Assumptions about the benefits of the visual system

The benefits of polarization sensitivity are not entirely clear; however, other animals use polarization vision for mating signals and covert communication without attracting the attention of predators. This mechanism may confer an evolutionary advantage; it also requires only minor changes in the cells of the eye and can easily develop under the influence of selection.

The eyes of mantis shrimp may allow them to distinguish between different types of coral, prey (which is often transparent or translucent), or predators such as barracuda with iridescent scales. Or the mantis shrimp's way of hunting (involving the extremely rapid movement of its claws) may require very precise information about space, in particular, an accurate perception of distance.

During courtship rituals, mantis shrimp actively fluoresce, and the wavelength of this fluorescence matches the wavelength perceived by the pigments in their eyes. Females are only fertile during certain phases of the tidal cycle; therefore, the ability to distinguish the phase of the moon helps to prevent futile efforts. It can also give the mantis shrimp information about the power of the tide, which is important for organisms living in shallow water.

According to some suggestions, the ability to see ultraviolet allows you to notice prey that would otherwise be difficult to recognize against the backdrop of a coral reef.

Studies show that the resulting color perception of mantis shrimp is not much different from that of a human. Their eyes are a mechanism that operates at the level of individual cones and helps the brain work. This system pre-processes visual information in the eye, not in the brain; otherwise, it would require a larger brain and a lot of energy to process such a stream of continuous data. Although their eyes are very complex and not yet fully understood, the principle of the system seems simple. It is similar to the human eye, only it works in reverse. In the lower temporal cortex of the human brain, there are a huge number of color-specialized neurons that process visual impulses from the eyes and create color images. Instead, mantis shrimp use different types of photoreceptors in their eyes, producing the same result as human color neurons. This is an innate and more efficient system for an animal that needs to constantly analyze colors. Humans have fewer photoreceptor types but more color neurons, while mantis shrimp appear to have fewer color neurons but more photoreceptor classes.

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Range and habitat

The vast majority of species live in tropical and subtropical seas at shallow depths. Mantis shrimp are edible and are found in the Far Eastern seas off the Russian coast. Common in the Mediterranean Squilla mantis. Large stomatopods are fished in the Indian and Pacific Oceans.

Lifestyle

Most stomatopods dig holes in the seabed. Small types of genera Gonodactylus and Coronida hide in crevices and crevices between coral branches. Some smaller species use the burrows of larger ones.

Distributed in warm seas and lead a predatory lifestyle. Stomatopods spend most of their time in burrows. Crawling out, they crawl along the surface of the ground with the help of their hind pectoral legs, as well as trapping legs, which at the same time bend and on which the cancer relies like crutches. Crayfish can swim quite fast. Mantis shrimp burrow into the soil with the front end of the body, wielding the rostrum and mandibles. The finished burrow usually has two exits, and the water, guided by the flapping of the anterior abdominal legs, flows freely through it. Burrows Lysiosquilla excavathrix reach a depth of 1 meter.

Notes

1. Birshtein Ya. A., Pasternak R. K. Superorder Hoplocaridae (Hoplocarida) // Animal Life. Volume 2. Mollusks. Echinoderms. Pogonophores. Seto-maxillary. Hemishordates. Chordates. Arthropods. Crustaceans / ed. R. K. Pasternak, ch. ed. V. E. Sokolov. - 2nd ed. - M.: Education, 1988. - S. 349-351. - 447 p. - ISBN 5-09-000445-5
2. Susan Milius (2012). "Mantis shrimp flub color vision test". science news. 182 (6): 11. doi:10.1002/scin.5591820609. JSTOR 23351000.
3. Thomas W. Corwin (2001). "Sensory adaptation: Tunable color vision in a mantis shrimp". Nature. 411 (6837): 547–8. doi:10.1038/35079184. PMID 11385560 .
4. "Evolutionary variation in the expression of phenotypically plastic color vision in Caribbean mantis shrimps, genus Neogonodactylus.". marine biology. 150.

The shrimp mantis is a truly unique creature. It has some features that are not found among other representatives of the terrestrial fauna, therefore it is the object of close study. Our article will tell you about these amazing crustaceans, their varieties and lifestyle.

Name and nicknames

The name is due to a certain resemblance to the praying mantis insect - a brave predator and a strong opponent for any natural enemy. But, in fairness, it is worth noting the following. If the praying mantis had to fight with the crustacean of the same name, he would not have had any chances. And the fight would hardly have lasted more than a few fractions of a second.

There are about 450. All of them have gained ambiguous fame, and therefore they are often called fighters, murderers, terrorists. In fact, these animals are not shrimp, much less praying mantis, it is more correct to call them stomatopods.

It is worth noting that nature has awarded stomatopods with a surprisingly beautiful appearance. Hence another nickname - peacock shrimps.

Characteristic appearance

Consider the features of the structure. What is the length of the body, the shape of the fighting limbs, and how many pairs of antennae does the mantis shrimp have?

Like all crustaceans, stomatopods have 5 pairs of limbs: the first pair is short sensitive legs, the second is a powerful weapon, the remaining three pairs are designed for walking. On the front of the body there are also pairs of antennae-antennae.

The mantis peacock shrimp can be up to 40 cm long, but representatives of the vast majority of subspecies usually do not exceed a decimeter.

Mantis shrimp strike

The folded limbs with which the stomatopods strike the enemy outwardly resemble the paws of a praying mantis. But the mechanism of their action is more like a crossbow. The muscle is stretched like a bowstring to throw the limb forward with a force comparable to a large-caliber pistol bullet when descending.

Just imagine: in the moment you blink, theoretically a mantis shrimp could hit the victim 50 times! To consider how the impact occurs, scientists can only use high-speed slow motion shooting.

It is also interesting that the mantis shrimp, whose impact force reaches 150 kg, weighs less than 100 grams. And the speed of departure of the limb can reach 80 km / h. This is comparable to an overclocked bus.

cavitation explosion

Scientists have discovered another unique ability of stomatopods. They hit the victim not only with the help of kinetic energy. Ultra-fast movement, which no other living creature on the planet is capable of, creates even faster eddies underwater. Water particles are heated to enormous temperatures. The resulting cavitation bubble explodes at the moment of contact with the body of the victim.

To observe this phenomenon, researchers have to slow down the shooting by 50,000 times.

The mantis shrimp easily copes with the shells of crabs, crushes and cuts off their claws, can kill fish passing by at high speed to death, and often attacks even those who are many times larger than it (for example, octopuses). Experienced divers try not to touch the stomatopods, because for curiosity you can pay with broken and even torn off fingers.

"Crushers" and "Piercers"

Scientists divide all stomatopods into 2 groups, each of which includes many species. The former are armed with claws resembling heavy maces, which is why they are called "crushers". At the ends of the limbs of the representatives of the second group there are spikes resembling bayonet-knives. This group is conditionally called "piercers".

In the behavior of the first and second, there are also some features. Most of the "crushers" live in cracks in the natural folds of the relief. "Piercers" prefer to build their own dwellings - they dig holes.

unique eyes

Phenomenal vision is another gift of nature that the mantis shrimp has received. Photos of stomatopods allow only a partial assessment of the capabilities of their eyes. In the illustrations, we can see that the organs of vision work autonomously from each other, which allows us to view the space almost 360 degrees.

However, we can learn the most interesting things only with the help of high-precision modern technology.

The human eye has 2 types of receptors. The mantis shrimp has 16 of them! Stomatopods see not only in black and white and color, but also in infrared and ultraviolet. In addition, they are able to recognize polarized light.

For comparison, we can cite the fact that all the shades we see consist of three primary colors: blue, yellow and red. And the mantis shrimp has not 3, but as many as 16. The human brain simply could not analyze the extravaganza of color that is available to stomatopods.

Mantis in the aquarium

Spectacular appearance and active behavior, which is certainly interesting to watch, could not go unnoticed by aquarists. In their environment, stomatopods are called mantis shrimp. But if you dreamed about such a pet, do not flatter yourself. A handsome man, like no other, capable of seeing beauty, will destroy everything around him and quickly kill his neighbors. The shrimp mantis will easily deal with aquarium glass, because its blow is comparable to a shot from a 22-caliber pistol.

In research labs, these creatures are kept in high-impact plastic containers. And only one by one. After all, engaging in battle with a relative for stomatopods is a common thing. And the shell that protects the mantis shrimp is powerless against the claws of its fellow. Such fights invariably end in the death of one of the fighters. In the underwater world there is no proportional creature capable of defeating the mantis shrimp, but this is within the power of its relative.

Promising Research

The shrimp praying mantis is of interest not only to wildlife lovers. They are very interested in the military, because the unique structure of the claw-sledgehammer can form the basis for the development of the latest weapons. American biologists are already working on a secret order from the US Department of Defense.

But the formidable predator of the mantis shrimp can also do a good job. Its unique eye, the structure of which a person has not yet been able to reproduce artificially, can become the basis for the development of diagnostic equipment. It has been established that stomatopods can even see cancer cells. If scientists manage to create a lens similar to the eye of a mantis shrimp, this will allow us to recognize tumors in the early stages, before metastases appear.

Research is ongoing. Scientists working with these amazing crustaceans suspect that they have not revealed all their secrets to modern science.

Scientific name: Odontodactylus scyallarus (Odontodactylus scyallarus)
Common names: peacock mantis, painted mantis, harlequin mantis, mantis shrimp
The size: 3-18 cm
Minimum aquarium size: 5 l
Aggressiveness: Aggressive. Will attack other aquarium inhabitants.
22-25°С, sg 1.023-1.025, pH 8.1-8.4, dKH 8-12
Food preferences: Carnivorous
Spreading: Indian and Pacific Oceans, from Guam to East Asia

General information:
Everywhere among aquarists this species is known as Odontodactylus scyallarus. This wonderful crustacean is one of the 500 species of stomatopods known today. These are predatory crustaceans, originally from the Indian and Pacific Oceans, where they can be found on sandy, stone or shell bottoms, often close to reefs at a distance of 3-40 m. This predator uses its wonderful eyesight while hunting, quietly and calmly waiting for prey will not be in range, and then grabs it with his second pair of legs.

These shrimp got their name due to their external resemblance to an insect - a praying mantis. Individual representatives of this species can reach up to 30 cm in length, and sometimes even large individuals were found. The shell of this shrimp covers only the back of the head and the first three segments of the chest. Their color is quite diverse, ranging from various shades of brown to bright neon colors.

This type of shrimp, as a rule, try not to settle in a common reef aquarium. Even more, these shrimp are considered pests and often get into the aquarium by accident, along with live rocks. If aggressive mantis shrimp are launched into the common they will begin to hunt and kill their neighbors. If you hear strange rattling noises from the tank at night and/or your fish disappear from the tank, there is a good chance that a peacock shrimp got in.

However, despite the fact that most aquarists consider them pests, mantis shrimp have their own fans, many of whom run species aquariums specifically for them. If you also had such an idea, remember that these shrimp should live alone in the aquarium. These creatures are very aggressive and will fight for territory. It is very important not to keep any fish with them, as these shrimp are carnivorous and very voracious. In a home aquarium, peacock shrimp can be fed frozen squid, shrimp, and crab.

In order for these shrimps to feel good and be satisfied, they definitely need a sandy bottom and some kind of mink or cave where they can hide after molting. They should not be very deep - crevices or holes in living stones will be enough. If there are no live stones in the aquarium, a piece of PVC pipe will do. In order for a shrimp to look healthy and with a good shell, you should avoid too much light, which in peacock mantises spoils it, which makes the shrimp more susceptible to disease.

And the final words about these fascinating, although not so easy to keep, creatures - if possible, large mantis shrimp should live only in acrylic aquariums. The impact force of a large adult of this species is equal to a 22-caliber bullet. These large shrimp have been known to break glass aquariums, either while digging in the substrate or by throwing themselves straight at the glass. That is why it is desirable to keep them in strong, stable acrylic aquariums.