The main environment for the life of the mantis shrimp is coastal marine waters. The animal prefers to stay in shallow water at a depth of at least 5 m. The lower limit of habitat is 3 m from the surface of the water. For life chooses areas with sandy or slightly silted bottom. It is found in the western part of the Pacific Ocean, the greatest density falls on the coastal waters of the Sea of Japan. In the waters of Russia, the only place where mantis shrimp meets is Peter the Great Bay, which is also the northernmost point of distribution of the species.
The mantis shrimp is a rather large representative of crustaceans, its length reaches almost 20 cm, and with claws it is even more. The body of cancer consists of segments, five thoracic are fused with head and form the so-called jaw-chest. Five pairs of thoracic limbs are transformed into the maxilla. The fishing apparatus has several outgrowths on the inside to capture prey and resembles the fore extremities of the praying mantis, for this resemblance the cancer got its name. The eyes are large, located on mobile stalks. The abdominal segments are quite large with distinct crests. The color of the body is light - from almost white to green, with a few bright spots on the last segments of the abdomen.
Mantis shrimps are exclusively bottom-dwelling. Most of the time they spend in shallow vertically dug burrows, allowing them to unfold freely. The burrows serve not only to protect against enemies, but are also a great place to ambush. The mantis shrimp patiently and motionlessly waits at the entrance for a small fish passing by, then throws out its claws with lightning speed and kills the victim.
The diet of the animal consists of a variety of crustaceans, shrimps, small fish and even crabs. Mantis shrimps have a unique ability that is not characteristic of other invertebrates: they can recognize individual individuals of their own species. This is possible due to individual odors - specific labels, which are a mixture of various organic substances that each individual leaves in the water.
The crayfish breeding period occurs at the end of May - the beginning of June. At this time, the males arrange between themselves ritual battles, during which they clap each other with claws. Sometimes these bouts end in the death of one of the participants. The winner mates with the female, the process itself lasts no more than a minute. The first three months of the young crustaceans spend in the water column. Life expectancy is about four years.
In the Red Book of Russia
Today, mantis shrimp is not endangered. In most of the range, the number of species is quite high, which allows you to catch an animal on a commercial scale. For example, in Japan, mantis shrimp is used to prepare many traditional dishes, here it is called shako. In Russia, due to the regional range, the number of individuals in the population is low and, according to indirect data, decreases. In the near future, it is important to introduce catch limits for mantis shrimps in Russian territorial waters.
It is interesting
Among all representatives of the animal world in mantis cancer, perhaps the most sensitive eyes. Human color vision is provided by only three types of receptors, while cancer has 16 of them, and 12 of them perceive the colors of the visible spectrum. Due to this, animals are able to distinguish up to 100 thousand colors and shades, while a person can hardly recognize 10 thousand. In addition, the eyes of a mantis shrimp can detect polarized light and four colors of the ultraviolet part of the spectrum that a person does not see at all. Some species of mantis shrimps are very variegated and have bright spots on the body, this provides a kind of communication between different individuals.
Mantis shrimp is a threat to the bottom dwellers of the sea, especially for small fish. Thanks to powerful claws with several sharp thorns, he instantly kills the victim and drags him to his refuge. The main feature that makes him a deadly hunter - the speed with which claws are thrown. Scientists calculated that at the time of the defeat of the victim, it is 20 m / s. If we consider the size of the cancer, then this is one of the most agile animals. The piercing blow of his claw is comparable to the action of a small bullet.
It is a mantis shrimp (Stomatopoda), a unique creature in many ways.
For example, the second name of a mantis shrimp is shrimp-mantis. But in reality he is neither cancer, nor shrimp, nor a praying mantis. This living fossil is a separate species of rotape. And aggressive and quite dangerous.
It lives in shallow depths in tropical and subtropical seas. Moreover, this cancer has an excellent memory and is able to memorize the individuals that live near it. He distinguishes his neighbors both by visual signs and by smell.
But this is not the most interesting thing about mantis shrimp.
Eyes that everyone sees
If a person can distinguish between 3 primary colors, then a mantis shrimp sees 12, that is, 9 more than we do. Imagine a color that cannot be imagined, then do it 8 more times. However, in fairness, a mantis shrimp poorly distinguishes colors that a person sees.
In addition, the mantis shrimp perceives ultraviolet and infrared light, and also sees different types of polarization of light: both linear and circular.
Minute of entertaining physics. Ultraviolet radiation (as well as infrared) is more or less familiar to us: here is the light spectrum of 7 colors of the rainbow, and here there are two more radiations beyond the limits of the spectrum, on both its sides. And the human eye can no longer see these radiation, they are called ultraviolet and infrared light.
But with polarization, everything is not so simple.
The person is sensitive to color (wavelength) and the brightness of the light. But the third, equally important characteristic, polarization, is generally not available to us. Polarization is the oscillation of a light wave in space. To understand what it is, imagine the strained rope on which the light "lies". If we shake the rope on one side, then the light will wave in inertia. Such oscillations will be called linear.
And if we shake the channel with circular movements, the waves of light, moving forward, will begin to describe the circles. This is circular polarization.
All this exists next to us, but we do not see! A cancer mantis sees!
In general, the polarization of light is a phenomenon in which all extra electromagnetic waves are “removed” from the “common” light, and only those that lie in the polarization region remain. The human eye is not able to see polarized light, but we encounter the very effect of polarization every day: using anti-glare lenses in sunglasses or filters for cameras.
Also, a person, for example, has binocular vision: our eyes create two pictures (in the image for each eye), which are combined into one. But the eyes of a mantis shrimp see 3 images at once! Each! Total - 6 pictures at a time. It can be said that a mantis shrimp has sekstakular vision.
Such superman eyes allow crustaceans to recognize different types of corals, prey and predators.
Striking power of impact
This amazingly beautiful animal is as dangerous as it is beautiful.
Praying mantises are of two kinds: “grabbers” and “attackers”.
The first have a nondescript look and live in the sand. They catch what floats above their heads. Such a cancer is the owner of several pairs of grasping legs (to remember how they look, imagine the front legs of a praying mantis). Moreover, the first pair of grasping legs is the largest and resembles a penknife. It is to her that a mantis shrimp catches its prey, and with the rest of its legs tries to keep it. A victim caught in such “hugs” has almost no chance of escaping.
The second crayfish, the “attackers”, are officially called peacock because of their colorful appearance. And unofficially - “thumb splitters”, which means “finger splitters”. In general, any praying mantis shrimps are very aggressive, but these, finding another animal dangerous or suspicious, attack the victim with a sharp, powerful kick, the strength of which is comparable to a hit of a 22 caliber bullet!
In this case, our underwater Mohammed Ali beats with such power that it literally breaks the water upon impact. At the site of the click of a claw, a so-called cavitation bubble is formed: an area filled with hot steam and gas released from the burst water. The temperature of these bubbles is comparable to the temperature on the surface of the sun! They literally glow in the dark.
This bubble instantly bursts, after which a powerful shock wave is formed, which itself can kill the victim. During the strike, the claw moves under water at a speed of 72 kilometers per hour, so that the hunting throw of mantis shrimps is officially recognized as the fastest among all animals.
Some aquarists in the pursuit of exotic pets rashly plant their mantis shrimp. Before the first pierced aquarium.
The mantis shrimp is not embarrassed that the sacrifice is much greater than themselves or if it is another crustacean with a powerful shell. The first blow rotates the victim stunned, and again finishes it. Moreover, the mantis shrimp is almost the only crustacean capable of stalking its prey, and even if the animal misses the attack for the first time, the victim will be unsung.
The secret of such speed and tremendous strength lies in the special structure of the hunting paws of the mantis shrimp. These animals use the so-called “latch mechanism”: their paws contain a large muscle, which contracts for a very long time, and a latch that holds back this very muscle. And at the moment of impact, the latch opens, and the muscle straightens out at a tremendous speed - something like a shot from a bow or crossbow is obtained.
Also on the hunting paws of crayfish mantises of both species there is a chitinous structure in the form of a saddle. This structure has a complex name: a hyperbolic paraboloid or a saddle (anticlastic) surface. And until recently, humanity believed that it was it who invented it (erroneously, by the way).
The hyperbolic paraboloid is known to engineers, architects and jewelers as a very strong surface: curved on both sides, it distributes pressure evenly over the entire surface. And she is known to lovers of chips.
It is very simple, but at the same time strikingly strong form, which in the case of mantis shrimps enhances the effect of the spring: unclenching, giving the blow maximum force.
Why the paws of the mantis cancer are not worn out and not broken? The secret of their strength is in the content of the hydroxyapatite mineral, which absorbs the impact force. This mineral is also found in the human body: in the teeth and bones. It is thanks to him that our bones are so strong. But in a mantis shrimp, hydroxyapatite fibers are arranged in a spiral, which makes the surface of the fists as strong as possible and does not allow microscopic cracks to develop into fractures. This structure is called the Buligan structure and has no analogues in the animal world.
Once, scientists placed microphones in an aquarium with mantis shrimps and unexpectedly recorded unusual sounds that resembled the roar of dinosaurs. This happened relatively recently, so that biologists still do not know exactly how and why animals “sing”, and most importantly, how these sounds are made.
But they sound frankly frightening.
Other texts of Sasha Roush about the animal world can be found on her Telegram channel Viridi Green.