The phylum of mollusks is divided into 7 classes: unshelled, monoplacophoran, armored, spadepod, bivalves, gastropod and cephalopod.
Shellless (Aplacophora) molluscs have a worm-like body up to 30 cm long, entirely covered by a mantle, and no shell. On the ventral side they have a groove with a ridge - the vestige of a leg. Nephridia are absent. This group of mollusks are hermaphrodites.
One of two subclasses - sulcate-bellied mollusks - live in the seas at depths from 15 m to 4 km. They burrow into the mud or live on corals. 250–300 species.
Monoplacophora are marine, predominantly fossil forms. The head and leg can be pulled into the shell by muscles. They breathe with 5–6 pairs of feathery gills. The heart consists of 2 ventricles and 4 atria. The nervous system includes four longitudinal nerve trunks connected by a peripharyngeal ring.
The heyday of monoplacophorans was from the Cambrian to the Devonian. To date, 1 genus with 8 species has been preserved.
The class of armored mollusks (Polyplacophora) includes about 1000 species of marine bottom animals, found in all seas, mainly in shallow waters. Shellfish live on rocks and rocks and feed on algae and detritus. Some of them are consumed by humans as food.
The oblong body, 0.5–30 cm long, is divided into a head, torso and leg, with which the shelled mollusks stick to the substrate. The dorsal side of the body is covered with a shell consisting of eight scutes. The respiratory organs are gills, the heart consists of two atria and one ventricle. The sense organs include eyes, located on the dorsal surface of the body, and organs of touch. Most shell mollusks are dioecious with external fertilization; develop with metamorphosis.
The body of spadefoot (Scaphopoda) molluscs is enclosed in a tusk-like shell. Body length 0.4–25 cm. There are holes at the ends of the shell; through the front of them, spadefoots can extend their head and leg outward. Above the base of the head there are hunting tentacles that serve for touching and capturing food (mainly foraminifera). These mollusks are dioecious; external fertilization. A floating larva emerges from the egg.
About 600 species lead a burrowing lifestyle in the seas at various depths (up to 6 km).
The shell of bivalve mollusks consists of two valves that cover the body of the mollusk from the sides. From the back, the valves are connected to each other by an elastic bridge - ligament, and from the inside - by muscles. The thickened dorsal edge of the valves bears projections that form a lock. The shell has dimensions from several millimeters to tens of centimeters. The giant tridacna grows up to 1.5 m in length, and the weight of this animal can exceed 200 kg. Tridacna can live up to a hundred years.
Bivalve mollusks have no head - this is the result of adaptation to a sedentary lifestyle. For the same reason, the sense organs are poorly developed: there are organs of touch, balance (statocysts), and chemoreceptors (osphradia on the gills). Some have eyes. On the ventral side of the body there is a leg that serves for attachment to the substrate. Respiratory organs are double-pinnate gills (in primitive forms) or gill plates. The heart consists of a ventricle and two atria.
The class has been known since the Cambrian. About 150 families and 20,000 species. Bivalve molluscs, found in marine and fresh waters, feed on plankton and detritus, filtering water through siphons at the back of the shell. Some drill into hard rock and wood (using the sharp teeth of a shell or dissolving the rock with the acid released). Shipworm damages the bottoms of ships and piers, boring long passages into them. Some bivalves (oysters, mussels, scallops) are eaten.
The shells of gastropods (Gastropoda) mollusks are twisted into a spiral and are distinguished by a wide variety of shapes. In some mollusks, the shell is immersed inside the body or is absent altogether. On the head there are a pair of tentacles with eyes. During evolution, gastropods have lost bilateral symmetry. In many species, symmetrical organs located on the right side of the body were reduced. Some species have a kind of lung - a cavity filled with air or water with oxygen dissolved in it. There are both hermaphrodites and dioecious forms.
Various species of the class live on land (from alpine highlands and tundra to tropical forests and deserts) and in water. Land snails, which live for several years, endure the winter in hibernating burrows clogged with mucus. Aquatic forms crawl along the bottom; some are part of the plankton, moving with the help of a modified fin or keel leg. A typical freshwater representative is the pond snail. The shells of the porcelain cowrie snail were used in many countries as coins, and red and violet dyes – purple – were extracted from murex. Slugs are agricultural pests. Grape snail consumed by humans as food. About 40,000 (according to some sources, more than one hundred thousand) species are divided into three subclasses: prosobranchial, opisthobranchial and pulmonate. Extinct gastropods have been known since the Cambrian or even Proterozoic; 15,000 species.
The class Cephalopoda is the most highly organized group of mollusks. The head is clearly separated. Part of the leg has evolved into 8 or 10 tentacles ("arms") surrounding the mouth. At the end of the tentacles, with which the animal grabs prey, there are suction cups, often equipped with horny hooks. The mouth contains powerful horny jaws, reminiscent of a parrot's beak. With its help, cephalopods tear food apart, and the teeth of the radula grind it into pulp. The fact is that the brain of these mollusks surrounds the esophagus on all sides, preventing them from swallowing large pieces of food.
Remains of the shell are sometimes preserved under the skin in the form of a horny plate; the external shell was found mainly in extinct forms. The only modern cephalopods that still retain an external spiral shell are nautiluses. The circulatory system is well developed; blood has a blue color due to hemocyanin, which is part of red blood cells. Cephalopods breathe with gills; some are capable of staying on land for a long time (several hours or even days) thanks to the water stored in the mantle cavity.
At the entrance to the mantle cavity there is a funnel (siphon), which is the second part of the modified leg. Thanks to the reactive force arising from the water thrown back from it, the animal moves forward with the rear end of its body. Muscle contractions occur with a very high frequency, which ensures uniform movement. This is achieved, in particular, by the high conductivity of the nerves - in some squids their thickness reaches 18 mm. The squid has a recorded speed of 55 km/h. Cephalopods can also swim, helping themselves with their tentacles. Some squids, pushing water out of a siphon at the surface of the sea, can rise several meters into the air.
The organs of vision are perfect. Eyes, similar to humans, have a lens and a retina; in giant squids their size exceeds 40 cm. There are also miniature thermolocators on their fins. Sensitive organs of smell (or taste) are concentrated on the inner surface of the tentacles and on the suckers. The developed organs correspond to a large brain.
For passive protection from enemies, autotomy is used (cephalopods “throw away” the tentacles by which the enemy grabbed them) and ink curtains, possibly poisonous, are sprayed to the side. In addition, special cells scattered throughout the skin -
Cuttlefish and squid. Top row, left to right: common cuttlefish, firefly squid, giant squid, Tasmanian euprymna. Bottom row, from left to right: common cuttlefish squid, flying squid, Atlantic squid, common loligo Cephalopods live in the seas (up to a depth of 5 km), preferring warm bodies of water. Some forms live among coastal rocks, others at great depths. Some swim in the water column, others crawl along the bottom. Almost all are predators, feeding on fish, crustaceans, and other mollusks; prey is caught with tentacles, killing it with the secretion of poisonous glands. Many cephalopods (squid, cuttlefish, octopuses) are consumed by humans. The class is divided into two subclasses: quadribranchs (extinct ammonites and the only extant genus of nautiluses) and bibranchs (cuttlefish, squids, octopuses and extinct belemnites). About 600 modern species.
Indeed, squids, unlike cuttlefish or octopuses, do not seek to charm the female, trying on catchy colors and protecting a convenient area of the bottom from competitors, and not proudly displaying prominent parts of their body, hinting at their readiness for a prolonged act.
The main characteristic of the process of how squids reproduce is speed and practicality, no sentimentality, only a short meeting to transfer the necessary part of mating - the spermatophore. Squid reproduction occurs using a special tube containing sperm, the length of which can vary from a centimeter to a meter. A spermatophore is a rather complex biological device, equipped with a powerful ejection apparatus, a sensitive hair, a complex shell and a kind of “tube” that releases glue.
Initially, the spermatophore is located in the male's needham sac and is transferred to the female upon meeting with the help of a penis or a modified hand equipped with special clamps that provide a strong grip. There is a place on the female’s body intended for placing the spermatophore; depending on the type of squid, this can be the oral membrane, a hole in the area under the beak or on the back of the head, the inner side of the mantle or the gill area. Having gotten rid of the “cargo,” the male leaves his girlfriend and no longer participates in the reproduction process; sometimes a long period passes from the moment the tube with sperm is handed over to fertilization. It is possible that the father of the little squids has long been dead when they are born, since the male is quite unceremonious and can calmly transfer the spermatophore to a female who has not yet reached puberty and is not capable of spawning.
As soon as the spermatophore is removed from the male and attached to the body of the female, its membrane comes into contact with sea water, causing the sensitive hair to rupture the thin membrane, provoking the so-called spermatophore reaction.
Water penetrates inside the spermatophore and puts pressure on the spring, due to which the inner shell of the cunning natural device also breaks. The spring literally flies out and pulls out the inner part of the organ, but at the same time the “tube” is triggered, releasing glue that securely fastens the sac with sperm to the female’s skin.
It turns out that the sperm is ready for spawning and all that remains is to wait until the female decides to reproduce, which, by the way, happens only once in the life of squids. If the female is a sexually mature individual, she will soon begin to lay eggs, which pass near the spermatophore attached in the gill area. When placing the device on the back of the head, sweeping occurs through holes located on the sides of the neck, but in any case fertilization is guaranteed.
Thus, several dozen eggs are laid, which the female can hide in a secluded place, for example, among dense thickets of algae. However, spawning often occurs directly at the bottom, where there is a concentration of squid, and many clutches of whitish and oblong eggs look like a huge carpet.
In most species, the larvae bear little resemblance to their parents immediately after birth, but within 2 months the small squid change in appearance and become sexually mature participants in the endless chain of spermatophore transmission.
By the way, there is still a mystery in the reproduction of some species of cephalopods, for example, in the species of hook-bearing squid, no males have been found, however, fertilization with the help of a spermatophore occurs, and the apparatus is placed in a long incision on the abdomen, which the female cannot make with her beak.
Deep-sea inhabitants of the depths of the sea are in no hurry to reveal their own secrets to humans; you can know how squid reproduce, but not imagine what makes this species of cephalopods literally produce offspring, without showing the slightest sympathy for each other.
Scientific mysticism. In Japanese cuisine there is a dish called “Dancing squid" The clam is placed in a bowl of rice and topped with soy sauce. The killed animal begins to move. Mystic? No. The sauce contains sodium.
The squid's nerve fibers react to it by contracting. Interaction is possible within several hours after the mollusk is caught from the sea. Have you ever caught pike?
When cutting it after 5-10 hours of lying out of the water, you find that the fish is twitching and its heart is beating. What about chickens running around after their heads are separated? So, there is no surprise in the posthumous dances of the squid. There is more of it in the creature's life. Let's talk about her.
Description and features of squid
It is called the primate of the sea. This indicates the upper stage of evolution that the squid occupies among cephalopods. In his class, the hero of the article has the most developed brain and even has a cartilaginous semblance of a skull.
Bone formation helps protect the thinking organ. It enables the squid's complex behavior. The animal is capable of cunning, deception and other intellectual tricks.
The trick is to combine the brain with other organs and functions of the animal. Yes, y giant squid the thinking center is shaped like a donut. The hole in the center is reserved for the esophagus. In other words, squid - shellfish, which eats through the brain.
The mouth of the hero of the article is so powerful that it resembles the beak of a bird. The density of the chitinous jaws allows them to pierce the skulls of large fish. The animal doesn’t care about thick fishing line either; it bites through it.
If the mollusk is nevertheless caught and ends up in a human mouth, embarrassment may occur. There have been several recorded cases of undercooked squid expelling sperm. Most precedents are recorded in Japan and Korea. Thus, in January 2013, mollusk sperm caused the hospitalization of a visitor to one of the restaurants in Seoul.
Sea squid in the “dancing” dish came to life when they began to chew it. The animal threw 12 spindle-shaped sacs of sperm into the mucous membrane of the restaurant visitor’s tongue and cheeks. The foreign substance caused a burning sensation. The woman spat out the dish and called the doctors.
No such cases have been recorded in Russia. There are regions where squid is a common dish, for example, the Far East. However, in our country, shellfish are cleaned of internal organs and boiled well. In Asian countries, squid are rarely cleaned.
The squid is classified as a cephalopod due to its body structure. The limbs do not come from him. The leg, transformed in the process of evolution into 10 tentacles, extends from the head of the animal, surrounding the mouth. The eyes of the mollusk have a familiar location. The structure of the organs of vision is similar to that of humans. At the same time, each eye is able to follow a different object.
The squid's body is a muscular mantle with a thin plate of chitin. It is located on the back and is the remnant of the shell. Squids do not need its frame, because they have developed jet propulsion.
By taking in water, contracting their bodies, and throwing out currents, mollusks swim faster than many fish. When spaceships and the first rockets were created, scientists were inspired by squids. Next, details about their lifestyle.
Squid lifestyle and habitat
Lanterns could also be invented by looking at squids. Their bodies are equipped with photophores. In caught mollusks these are bluish dots on the skin. If big squid, photophores reach a diameter of 7.5 millimeters.
The structure of the “lamp” is reminiscent of the design of car headlights and lanterns. The light source is bacteria. They feed on squid ink. The mollusk fills the photophores with dark liquid when it wants to turn off the light. By the way, on the body of one mollusk there can be “lamps” of 10 different designs. There are, for example, “models” that can change the direction of the rays.
Some squids are even named after their ability to beam. Thus, the Firefly lives in Tayami Bay off the coast of Japan. More precisely, the mollusk lives at a depth of 400 meters. The colony washes ashore in June-July. This is the time for excursions, when tourists admire the bright blue waters of the bay. Scientists, at this time, are racking their brains as to why squids need photophores. There are several versions.
The most realistic: - light attracts cephalopod prey, that is, small fish. Second opinion: - the glow of squids scares away predators. The third assumption regarding the role of photophores is related to the communication of mollusks with each other.
400-500 meters is the standard depth limit at which it can live squid. Lives Below is just a gigantic view. Its representatives are also met 1000 meters under water. At the same time, the giant squid rises to the surface. Specimens measuring 13 meters long and weighing almost half a ton were caught here.
Most squid live at depths of about 100 meters, searching for muddy or sandy bottoms. Cephalopods flock to it in winter. In summer, squids rise to the surface.
Most of the population lives in the North Atlantic Ocean. Here squid fishing carried out from to the North Sea. The Mediterranean is also rich in cephalopods.
Squids are also found in the Adriatic. It is difficult to track individuals because the animals migrate. The incentive to move is the search for food. In addition to fish, crustaceans, other mollusks, even relatives are used.
They are caught with two tentacles, injecting paralyzing poison into the victim. The squid tear off small pieces of flesh from the immobilized ones, slowly eating them. Having gained strength and waited until summer, squids begin to reproduce. Fertilization leads to the laying of eggs. It looks like a sausage, with a film on top and eggs inside. Afterwards, the parents leave.
After about a month, centimeter-long offspring are born, immediately beginning an independent life. It is possible only where the water salinity is 30-38 ppm per liter of water. This is why there are no squids in the Black Sea. The salinity of its waters does not exceed 22 ppm.
Types of squid
Let's start with the Pacific squid. This is what we usually see on the shelves of domestic stores. True, Russians are accustomed to calling the mollusk Far Eastern, after the place of catch.
The sizes of individuals start from a quarter and end with half a meter. This is along with the tentacles. Single squids reach 80 centimeters. The species lives at depths of up to 200 meters. The desired water temperature is 0.4-28 degrees Celsius.
The second of the main types of squid is Komandorskiy. It is also sold in Russia, sometimes outpacing the Pacific in terms of sales. The commander's species is smaller, growing to a maximum of 43 centimeters.
Standard size is 25-30 centimeters. Representatives of the species are distinguished by their ability to swim to depths of up to 1,200 meters. The young live near the surface. This is what mostly ends up on the shelves. The extermination of the species became the reason for the founding of the Komandorsky State Reserve. Squid fishing is prohibited there.
It remains to mention the European squid. Meat one individual weighs up to 1.5 kilos. The body length of the animal is 50 centimeters. The species swims to depths of up to 500 meters, usually staying at 100 meters. Individuals have short tentacles and a light body. In the Pacific species it is, for example, gray, and in the Komandorsky species it is reddish.
There are also Giant, Peruvian and Argentine squid. They can only be seen outside of Russia. The big view was talked about. Peruvian is inedible. Harm to squid lies in the ammonia taste and, in fact, the content of ammonia itself in the meat. The Argentinean variety is tender in taste, but loses it when frozen. Sometimes, Argentine clams are found in cans.
Squid feeding
In addition to fish, crayfish, worms and the like, the hero of the article catches plankton. Another dietary product is associated with benefits of squid for the environment. Cephalopods feast on algae. Their squid is scraped off the rocks.
This improves the appearance of the bottom and prevents the water from blooming. If the target is a living creature, the hero of the article hunts from an ambush, tracking down the victim. The poison is injected by the radula. This is a set of cloves in an elastic shell. They not only deliver poison, but also hold prey while it tries to escape.
Reproduction and lifespan of squid
Squid seed sacs are located in a special tube. They could have met her while cleaning the carcasses. The length of the tube is from 1 centimeter to 1 meter, depending on the type of mollusk. Females receive seed material into a depression near the mouth, on the back of the head, or in the mouth.
The location of the fossa depends, again, on the species squid Price receiving sperm, sometimes months of gestation. Males do not select mates based on age. Often, the seed is transferred to an immature female and stored in her until reaching the reproductive period of life.
When children appear, the father may no longer be alive. Most squids die at the age of 1-3 years. Only giant individuals live longer. Their limit is 18 years. Old squid, as a rule, lose their taste and are harsh even with minimal heat treatment. So, they try to catch and prepare young animals for food. Its meat is considered dietary.
Squid calories is only 122 units per 100 grams of product. Proteins account for 22 grams. Fats make up less than 3 grams, and only 1 gram is allocated for carbohydrates. The rest of the mass is water. In the bodies of squids, like most animals, it is the basis.
Squids are the largest and most agile cephalopods. About 300 species of these animals are known in nature, among which there are amazing life forms. Their closest relatives are octopuses and cuttlefish. The hellish vampire squid, classified as a separate order, occupies a special systematic position. In fact, it is an intermediate form between squid and octopus.
Southern sepioteuthis squid (Sepioteuthis australis).
The general physique of squids is similar to octopuses and cuttlefish. Their internal organs are placed in a cavity sac - the mantle. The large head is crowned in front by a bun of 8 arms. In addition, near the mouth there are two more hunting tentacles armed with powerful suckers; in some species the suckers turn into hooks.
A squid with outstretched arms and hunting tentacles.
Between the tentacles are beak-shaped jaws. The blood of these mollusks is blue. The excretory organs of squid produce ammonia, which gives their meat a specific smell. Like cuttlefish and octopuses, squids are highly intelligent; their brains are enclosed in a cartilaginous box - a kind of prototype of the skull. True, their chromatophores (pigmented skin cells) are very poorly developed, so squids cannot change body color and thus transmit signals to their relatives. But their intelligence is manifested in the ability to quickly process information, which is very important for such active animals. These mollusks have the thickest nerve fibers among all living creatures, their thickness (and therefore the speed of the nervous system) is 100 times greater than the thickness of human nerves!
The eyes of squids are relatively large and are similar in structure to the eyes of vertebrates. They also have binocular vision, which allows them to focus their gaze on prey and determine the distance to it with great accuracy.
Squids differ from other cephalopods in their oblong-cylindrical body shape. They do not have membranes between the tentacles, but on the sides there are small diamond-shaped wings. In some species they can stretch almost the entire length of the body, and this makes squids similar to cuttlefish. Wings play a supporting role in swimming. The forward movement is carried out by pushing water out of a special siphon tube, thus creating a very powerful jet stream. Squids can turn the siphon in different directions and instantly change the direction of movement, reverse; moreover, if necessary, many species are able to jump out of the water and fly tens of meters above the waves.
Bartram's flying squid (Ommastrephes bartramii) glides above the waves with its tentacles and wings spread out.
The hellish vampire squid looks very unusual. This is the only species of these mollusks that has a real membrane between the tentacles. Because of this, it was first classified as an octopus, and only later did scientists discover signs of squid in this species. Now this species is classified as a special order and occupies an intermediate position between true squids and octopuses. This relict inhabitant of great depths received its unflattering name because of its bright red color and ability to phosphorescent in the dark; nothing else unites it with hell and especially vampires.
The hellish vampire squid (Vampyroteuthis infrnalis) reaches a length of only 37 cm and has nothing demonic in its appearance.
Most squids are not very brightly colored; they are more often white, bluish, and pinkish in color. Their body is devoid of complex patterns, but many of them are able to glow in the dark in purple or blue. This glow is provided by special bacteria that live in the tissues of mollusks. The accumulation of many phosphorescent squids is a fabulous sight! The sizes of these animals also vary widely. Most species of squid are small, their length ranges from 25 cm to 1 m. But there are exceptions to this rule. The smallest species is the dwarf piglet squid, barely reaching a length of 10 cm, and the largest is the giant squid. The existence of these animals has been known since ancient times; the northern peoples have many legends describing the kraken - a monster with tentacles that attacks entire ships. Scientists could not find the giant squid for a long time, so the kraken was declared a fiction. And only in the second half of the twentieth century, as a result of the development of the ocean, researchers began to come across, first, huge pieces of tentacles, and then the entire remains of colossal mollusks. Of course, they do not attack ships, but the size of the giant squid is amazing: it reaches 18 m in length, of which about 12 m are tentacles!
The pygmy piglet squid (Helicocranchia pfefferi) gets its name from its barrel-shaped body and tiny “snout”, which is actually a photophore.
Squids live exclusively in salty waters - from the warm tropics to the Arctic regions. In the seas and oceans they have mastered all niches: some species live in the water column at a depth of 100-500 m, others prefer to stay close to the surface, others are found exclusively at great depths (up to 1500 m) and never see the sun. Deep-sea squid are often solitary, but small species that live near the surface live in schools. All types of squid are very mobile and spend their entire lives swimming; they do not have permanent habitats. Moreover, many species perform daily vertical migrations, rising to the surface of the water at night, as well as annual spawning migrations. In the latter case, in three months of travel, squids cover more than 3000 km, that is, on average they swim 30 km per day! It is not surprising that their migrations take place at cruising speed. Flying squids are especially mobile; many of their species can reach speeds of up to 70 km/h! The smallest species, on the contrary, are planktonic; instead of actively swimming, they drift with the current. This drift is provided by another amazing ability of these animals - neutral buoyancy. In the body of planktonic squids there is a bladder filled with ammonium chloride (ammonia). This liquid is lighter than water, so the mollusks, even if motionless, do not drown.
The body of the Hawaiian short-tail squid (Euprymba scolopes) is colored with symbiotic luminescent bacteria (Vibrio fischeri).
Depending on the size of the squid itself, its prey can be both small planktonic organisms and relatively large animals: fish, pteropods, squid of other species, and even its own juveniles. The giant squid preys on large deep-sea fish. Cases of attacks on sperm whales are often attributed to this mollusk, citing its large size, but this is not true, since even the largest squid weighs up to 800 kg, and the sperm whale weighs 30-50 tons. It is clear that even with long tentacles, the giant squid is not able to cope with such prey. Contrary to the tales of sailors, it also never attacks ships, since it lives at great depths. No one has ever seen a living, healthy giant squid; only dead or dying specimens have fallen into the hands of researchers. Squids catch their prey using tentacles (not to be confused with hands), and in some mollusks the tentacles can significantly lengthen and shorten. By casting this unique fishing rod, the squid is able to catch prey without approaching it closely. Fluorescence is also used to lure victims.
This is what phosphorescent squids look like in complete darkness.
Reproduction in squids usually occurs once a year in certain spawning areas with a favorable hydrological regime. During this period, the males wrap their arms around the female and present her with a spermatophore. The female places this packet of sperm next to her eggs and immediately hurries to the bottom. One female lays up to several dozen eggs, similar to elongated snow-white cans. Sometimes the female hides them in a shelter, sometimes attaches them to algae, and more often places them on a flat bottom. In places of mass squid spawning, many clutches form a continuous carpet, which sways fantastically under the influence of currents. The larvae of many squids at first are not very similar to their parents, but they grow very quickly and reach sexual maturity by 1-2 years.
Mating Tasmanian squid (Euprymna tasmanica).
Since squids are common species of animals, they are hunted by everyone in the sea. Small species are eaten by gulls, albatross, petrels, as well as larger squid. Dolphins hunt for larger shellfish, and the largest and deep-sea species are the main food of sperm whales. They use many tricks to protect themselves from enemies. Firstly, squids, like octopuses, have an ink sac containing a dark liquid, which they release in case of danger, disorienting the enemy. Secondly, fast-swimming species rely on speed, including flight, which saves them from many fish. Finally, in deep-sea species, photophores (luminescent organs) serve as deterrents. It turns out that squids are able not only to passively glow, but also to regulate the glow, suddenly flashing with bright lights. Moreover, the magic lamp squid is capable of releasing a luminous liquid: while the enemy wanders in the sparkling cloud, the squid quietly disappears from view.
A newborn squid against the background of eggs, inside of which its fellow embryos are visible.
Squid are caught in large quantities in almost all fishing areas. Their meat is used in the cuisine of many countries; it is nutritious and tasty, cooks quickly and is easily digestible. The harvest of these animals must be regulated to avoid overfishing. Many deep-sea species are still little studied and are known from isolated specimens accidentally collected.
The message about the squid will tell you in detail about the life of these amazing creatures.
Message about the squid
Squids are the largest and most mobile cephalopods. They can move at a speed of 200 km per hour. By the way, squids are the closest relatives of cuttlefish and octopuses.
Usually have dimensions of 0.25-0.5 m, but giant squids of the genus Architeuthis can reach 16.5 meters
General characteristics of mollusks
In general, their physique resembles cuttlefish and octopuses. All internal organs of squids are hidden in a cavity sac - the mantle. The large head in front is crowned with a bunch of 8 so-called arms. Two more hunting tentacles are placed near the mouth. They are equipped with powerful suction cups, which in some cases turned into hooks.
Squids live only in salt water. Their habitat ranges from the Arctic regions to the warm tropics. Some of them are located at a depth of 100-500 m, other species stay on the very surface of the water, and still others live at great depths, not seeing the sun at all.
It is worth noting that squids are neutrally buoyant. There is a bladder in their body that is filled with ammonia. The liquid in the bubble is lighter than the water itself, so the squids, being motionless, still do not drown.
What do squids eat?
What squids eat generally depends on their size. They can feed on both small planktonic organisms and fairly large animals - fish, pteropods, mollusks and even their own kind.
Squids catch prey using their tentacles, which can contract and elongate to better grasp and hold it. Thus, he can catch the prey without coming close to it. Sometimes, in order to lure prey, the squid releases a special substance - fluorescence.
What types of squid are there?
There are approximately 300 known species of these creatures, but the most common and famous are:
- European
- Pacific
- Komandorsky
- Argentinian
- Ordinary
How do squids reproduce?
The process of reproduction in animals occurs once a year and only in certain spawning areas where the hydrological regime is favorable. When the time comes to reproduce, the male presents the female with a gift in the form of a spermatophore - a bag of sperm. The female places it along with her eggs, of which there may be more than a dozen, and hurries to the bottom. It happens that a caring mother attaches her clutch to seaweed, hides it in a secluded corner, or simply places it at the bottom.
