Marine life. Octopus. Description, features. How many legs does an octopus have? Octopus has 9 tentacles and releases ink

Octopuses are the most famous of the cephalopods, but nevertheless hide many secrets of their biology. There are 200 species of octopuses in the world, allocated in a separate order. Their closest relatives are squid and cuttlefish, and distant are all gastropods and bivalves.

Giant octopus (Octopus dofleini).

The appearance of the octopus is a little discouraging. Everything in this animal is not obvious - it is not clear where the head is, where the limbs are, where the mouth is, where the eyes are. In fact, everything is simple. The sac-like body of an octopus is called a mantle, on the front side it is fused with a large head, on upper surface with bulging eyes. The mouth of octopuses is tiny and surrounded by chitinous jaws - the beak. The beak is necessary for octopuses to grind food, since they cannot swallow prey whole. In addition, they have a special grater in their throats, which grinds pieces of food into gruel. The mouth is surrounded by tentacles, the number of which is always equal to 8. Octopus tentacles are long and muscular, their lower surface is dotted with suckers of different sizes. The tentacles are connected by a small membrane - umbrella. The 20 species of finned octopuses have small fins on the sides of their bodies that are used more as rudders than engines.

Finned octopuses due to pterygoid fins resembling ears, in English language They are called Dumbo octopuses.

If you look closely, you can see a hole or a short tube under the eyes - this is a siphon. The siphon leads to the mantle cavity, into which the octopus draws water. By contracting the muscles of the mantle, he forcefully squeezes water out of the mantle cavity, thereby creating a jet stream that pushes his body forward. It just turns out that the octopus swims backwards.

Just below the eye is the siphon of an octopus.

Octopuses have a rather complex device internal organs. Yes, their circulatory system almost closed and tiny arterial vessels are almost connected with venous ones. These animals have as many as three hearts: one large (three-chambered) and two small gills. Gill hearts push blood to the main heart, which directs the flow of blood to the entire body. Octopuses have blue blood! The blue color is due to the presence of a special respiratory pigment - hemocyanin, which in octopuses replaces hemoglobin. The gills themselves are located in the mantle cavity; they serve not only for respiration, but also for the excretion of decay products (together with the renal sacs). The metabolism of octopuses is unusual, because nitrogenous compounds are excreted not in the form of urea, but in the form of ammonium, which gives the muscles a specific smell. In addition, octopuses have a special ink sac that accumulates a dye for protection.

The funnel-shaped octopus suction cups use the suction force of a vacuum.

Octopuses are the most intelligent of all invertebrates. Their brain is surrounded by special cartilage, which surprisingly resembles the skull of vertebrates. Octopuses have well developed sense organs. The eyes have reached the highest perfection: they are not only very large (occupying most of the head), but also complex. The device of the eye of an octopus is fundamentally no different from the human eye! Octopuses see each eye separately, but when they want to take a closer look at something, they bring their eyes closer and focus them on an object, that is, they also have the rudiments of binocular vision. The angle of view of the bulging eyes approaches 360°. In addition, photosensitive cells are scattered in the skin of octopuses, which allow you to determine general direction Sveta. taste buds octopuses are located ... on their hands, more precisely on suction cups. Octopuses do not have hearing organs, but they are able to pick up infrasounds.

The pupils of octopuses are rectangular.

Octopuses are often colored brown, red, yellowish, but they can change color no worse than chameleons. Color change is carried out according to the same principle as in reptiles: in the skin of octopuses there are chromatophore cells containing pigments, they can stretch and contract in a matter of seconds. Cells contain only red, brown and yellow pigment, alternating stretching and contraction of cells different color creates a variety of patterns and shades. In addition, special irridiocyst cells are located under the layer of chromatophores. They contain plates that turn, change the direction of light and reflect it. As a result of refraction of rays in irridiocysts, the skin can turn green, blue and Blue colour. Just like in chameleons, the color change of octopuses is directly related to the color of the environment, the well-being and mood of the animal. A frightened octopus turns pale, and an angry one blushes and even turns black. Interestingly, the color change directly depends on visual signals: a blinded octopus loses the ability to change color, a blinded octopus changes color only on the “seeing” side of the body, tactile signals from the tentacles also play a role, they also affect skin color.

"Furious" blue reef octopus (Amphioctopus marginatus) of unusual coloring. At rest, these octopuses are brown with blue suckers.

The largest giant octopus reaches a length of 3 m and weighs 50 kg at the same time, most species are medium and small in size (0.2-1 m in length). A special exception is the male Argonaut octopus, which is much smaller than the females of its species and barely reaches a length of 1 cm!

The habitat of various species of octopuses covers almost the entire world, only in the polar regions you will not find them, but still they penetrate north further than other cephalopods. Most often, octopuses are found in warm seas in shallow waters and among coral reefs at a depth of up to 150 m. Deep-sea species can penetrate to a depth of 5000 m. Shallow-water species usually lead a sedentary benthic lifestyle, most of the time they hide in reef shelters, between rocks, under stones and come out only for hunting. But among octopuses there are also pelagic species, that is, those that constantly move in the water column away from the coast. Most pelagic species are deep sea. Octopuses live alone and are very attached to their site. These animals are active in the dark, they sleep with their eyes open (they only narrow the pupils), in a dream the octopuses turn yellow.

The same blue reef octopus in a calm state. These octopuses are very fond of settling in bivalve shells.

There is an opinion that octopuses are aggressive and dangerous to humans, but this is nothing more than prejudice. In reality, only the most large species and only during the breeding season. Otherwise, octopuses are cowardly and cautious. Even with an enemy of equal size, they prefer not to get involved, but hide from large ones by everyone. possible ways. There are many ways to protect these animals. First, octopuses can swim fast. Usually they move along the bottom on half-bent tentacles (as if crawling) or swim slowly, but when frightened, they can jerk at speeds up to 15 km / h. A fleeing octopus seeks to hide in a shelter. Since octopuses have no bones, their body has amazing plasticity and is able to squeeze into a very narrow crack. Moreover, octopuses build shelters with their own hands, surrounding the crevices with stones, shells and other debris, behind which they hide like behind a fortress wall.

Octopus in hiding surrounded himself building material- flaps of shells.

Secondly, octopuses change color, masquerading as the surrounding landscape. They do this even in a calm environment (“just in case”), and skillfully imitate any surface: stone, sand, broken shells, corals. The octopus imitator from Indonesian waters imitates not only the color, but also the shape of 24 species of marine organisms (sea snakes, stingrays, brittle stars, jellyfish, flounders, etc.), and the octopus always imitates the species that the attacking predator is afraid of .

Mimic octopus (Thaumoctopus mimicus) masquerading as a spiny lobster.

On soft soils, octopuses burrow into the sand, from which only a pair of inquisitive eyes sticks out. But all these methods of protection are nothing compared to the know-how of octopuses - the "ink bomb". They resort to this method of protection only when they are very frightened. A floating octopus releases a dark-colored liquid from its bag, which disorients the enemy and not only ... The liquid affects the nerve receptors, for example, deprives the sense of smell for a while predatory moray eels, a case is known when a liquid got into the eyes of a scuba diver and changed his color perception, for several minutes the person saw everything in yellow. The musk octopus also smells like musk ink. Moreover, often the released liquid does not dissolve in water instantly, but retains the shape of ... the octopus itself for several seconds! Here is such a decoy and chemical weapon slips an octopus on his pursuers.

And this is an octopus imitator, but already pretending to be a stingray.

Finally, if all the tricks did not help, the octopuses can enter into an open battle with the enemy. They show an unbending will to live and resist to the last: they bite, try to gnaw through the nets, try to mimic to the last breath (there is a known case when an octopus, pulled out of the water, reproduced on its body ... lines from the newspaper on which it was lying!), captured for one tentacle, the octopuses sacrifice it to the enemy and discard part of the arm. Some species of octopuses are poisonous, their poison is not fatal to humans, but causes swelling, dizziness, and weakness. An exception is the blue-ringed octopus, whose nerve-paralytic venom is lethal and causes cardiac and respiratory arrest. Luckily, these Australian octopuses are small and secretive, so accidents are rare.

Large blue-ringed octopus (Hapalochlaena lunulata).

All octopuses are active predators. They feed on crabs, lobsters, bottom mollusks, and fish. Octopuses catch moving prey with tentacles and immobilize with poison, and the suction force of the tentacles is great, because only one suction cup of a large octopus develops a force of 100 g. They gnaw through the shells of inactive mollusks with their beak and grind with a grater, the poison also slightly softens the shells of crabs.

Swimming giant octopus moves back side body forward and head back.

A clutch of spiny octopus (Abdopus aculeatus) peeps between the tentacles of a caring mother.

Female octopuses are exemplary mothers. They braid the masonry with their hands and carefully lull it, blow off the smallest debris with water from their siphon, they do not eat anything all the time they incubate (1-4 months) and eventually die from exhaustion (sometimes their mouths even grow). Males also die after mating. Octopus larvae are born with an ink sac and can make an ink veil from the first minutes of life. In addition, small octopuses sometimes decorate their tentacles with stinging cells. poisonous jellyfish, which replace their own poison. Octopuses grow quickly, small species live only 1-2 years, large ones - up to 4 years.

A giant octopus displays a web (umbrella) between its outstretched tentacles.

In nature, octopuses have many enemies, they feed on them. big fish, seals, sea ​​lions and seals, sea birds. Large octopuses can dine with a small relative, so they hide from each other no less than from other animals. People have been hunting octopuses for a long time. Most of these animals are harvested in the Mediterranean Sea and off the coast of Japan. In Eastern and Mediterranean cuisine, there are many dishes with octopus meat. When catching octopuses, they use their habit of hiding in secluded places, for this, broken jugs and pots are lowered to the bottom, inside which octopuses crawl, then they, together with a false house, are raised to the surface.

Common octopus (Octopus vulgaris) Paul "draws lots" - opens the feeder.

It is difficult to keep octopuses at home, but they are welcome guests in public aquariums. It is interesting to watch these animals, they can develop elementary conditioned reflexes, octopuses solve some tasks no worse than rats. For example, octopuses perfectly distinguish between various geometric figures, and they recognize not only triangles, circles, squares, but they can also distinguish a lying rectangle from a standing one. With good care, they recognize the person caring for them and greet him, crawling out of the shelter. The most famous pet was the common octopus Paul from the aquarium "Center marine life» in Oberhausen (Germany). The octopus became famous for accurately predicting the victory of the German football team during the 2010 World Cup. Of the two feeders offered, the octopus always opened the feeder with the symbols of the winning team. The mechanism of the "prophecies" remained unknown, Paul died in 2010 at the age of about 2 years, which corresponds to the natural life expectancy.

One of the most amazing adaptations that most cephalopods have evolved over the years is the ink bomb. The uniqueness of this weapon was the reason for writing this article.
If you have read articles on my site about the structure of octopuses, cuttlefish or squids, you have noticed that many of these animals have a special organ in their body - an ink sac filled with a special liquid - ink. At the moment of danger, cephalopods are thrown out of the funnel, with the help of which they carry out jet propulsion, a jet of these same inks.
Having blurred in the water in a thick opaque cloud, the ink creates, as it were, an inky veil, under the cover of which the mollusk quickly flees, leaving its enemy to wander in the dark.

Mollusk ink contains an organic substance from the melanin group, similar in composition to the pigment that is used to color human hair.
The shade of ink is not the same for different cephalopods: in octopuses it is usually black, and in cuttlefish it is brown.

Ink is produced in a special organ - a pear-shaped outgrowth of the rectum, called the ink sac. The ink bag is a dense vial divided into two parts by a partition. The upper part is reserved for a spare tank, it stores ready-to-use ink. The lower part of the bag is filled with the tissue of a special gland, its cells are stuffed with grains of paint.
Old, mature cells are gradually destroyed, their dye dissolves in the enzymes of the gland and ink is obtained, which goes to the "warehouse" - in the upper part of the ink bag. There they are stored until needed.

In case of danger, the mollusk does not throw out the entire supply of ink at a time. For example, an ordinary octopus can put six ink curtains in a row, and after half an hour it will completely restore the spent "ammunition".
The coloring power of the ink liquid is extremely high. For example, a cuttlefish in five seconds can completely color the water in a large aquarium with vomited liquid, and giant squid spewing from an ink funnel so much liquid that sea ​​water cloudy for hundreds of meters.

Cephalopods are born with sacs filled with ink and ready to use their defensive weapons. So, one little cuttlefish, barely getting out of the egg shell, marked its birth with five ink volleys.

Not so long ago, biologists did unexpected discovery. It turned out that the traditional idea of ​​the ink curtain of cephalopods should be thoroughly revised. Numerous observations of the use of their ink weapons by mollusks have shown that the ejected ink does not immediately begin to dissolve in water, but only when someone stumbles upon them or they stumble upon something.
The ink liquid can hang in the water for a long time (up to 10 minutes or more) as a dark compact drop. The most striking thing is that the shape of this drop resembles the outlines of the animal that threw it out - an octopus, cuttlefish or squid.
The predator, instead of the escaping mollusk, grabs this drop. That's when it explodes and envelops the enemy in a dense dark cloud. The shark is thrown into disarray when a shoal of squid simultaneously, like a multi-barreled mortar, throws out a whole series of ink bombs. The shark starts darting from side to side, grabbing one imaginary squid after another, and soon finds itself in a cloud of scattered ink.

In the middle of the last century, Dr. D. Hall published in the English journal Nature interesting observations on the maneuvers that the squid resorts to, replacing itself with an ink ghost.
The scientist put the squid in a tub and tried to catch it with his hand. When his fingers were already a few centimeters from the target, the squid suddenly darkened and, as it seemed to Hal, froze in place. In the next moment, the scientist grabbed... an ink mock-up, which turned into a dark cloud of ink. The deceiver swam at the other end of the tub. Hal tried again, but now he was watching the squid closely. Now he could see the process of forgery.
As his hand approached the squid, it did turn dark. Then he threw out an ink bomb and at that moment turned sharply pale, becoming almost invisible in the water, and darted invisible to the far end of the tub.
The scientist was struck by the subtlety of the execution of the maneuver. After all, Kalmar not only left an ink model in his place, he played a skillful performance!
First, he abruptly changed the color of the body to dark, attracting the attention of the enemy, then instantly replaces himself with another dark spot - an ink model. The predator automatically fixes its gaze on it, and at this moment the squid, having abruptly changed its color to an almost imperceptible one, instantly disappears from the scene.

It should be noted that similar experiments and observations were carried out as early as 1878 by the Belgian scientist L. Frederick, who wrote that the cuttlefish first throws out ink drops similar to it in shape and, thanks to such an imitation, escapes from enemies, but this observation was not given due importance .
This is often found with many discoveries that go against the generally accepted opinion of the scientific world. Almost a century passed before Frederick's observation was "discovered" again.

But that's not all about the amazing weapons of cephalopods.
It turned out that the ink liquid has another amazing property. The American biologist McGuinity conducted a series of experiments on the California octopus and the moray eel, two sworn enemies. And here's what he installed.
It turns out that octopus ink paralyzes the sense of smell predatory fish. Moray eels, having plunged into an ink cloud, cease to recognize the smell of an octopus lurking nearby, even when it stumbles upon it. The action of the octopus "drug" lasts more than an hour!
Later it was found that the effect of ink is dangerous for the cephalopods themselves, especially in high concentrations. In the wild, in the sea, the octopus avoids the ink by running away from the poisoned place. It is not easy for him to do this in a limited space.
In a pool or aquarium, octopuses can die if the concentration of ink in the water reaches a critical level.
This makes keeping octopuses and other cephalopods problematic in small aquariums. Although, if you make the water running, the problem can be solved. In addition, octopuses quickly get used to their owner-feeder and do not get nervous over trifles, releasing ink into the water.

Is cephalopod ink dangerous for humans?
The answer to this question can be found in the book "Spearfishing", published back in 1960 by the famous English writer D.Aldridge, an amateur and expert in spearfishing.
He's writing:
"... I behaved so freely with octopuses that I got a jet of ink right in my face. And since I was without a mask, the liquid got into my eyes and blinded me. The world, however, this did not darken, but turned into a wonderful amber color. Everything seemed amber to me, as long as the film of ink was held in front of my eyes. This lasted about ten minutes. Getting ink in my eyes didn't affect my vision in any way."

From this we can conclude that cephalopod ink is not particularly dangerous for humans.

It is interesting to note that deep-sea cephalopods that live in the eternal darkness of the sea abyss do not have ink weapons. This can be understood - why in total darkness ink? Instead, cuttlefish and squid, living in the dark, throw out a cloud of brightly glowing symbiotic bacteria that blinds the enemy.

Well, in conclusion, I would like to say that ink, for example, cuttlefish is used to prepare many dishes of oriental and Mediterranean cuisine. So the benefits of them are not only in paint and ink for writing.

Can an octopus really produce ink?

The ink contains an organic dye from the melanin group, similar in composition to the pigment that dyes our hair. The shade of ink is not the same for all cephalopods: for cuttlefish it is blue-black (in a strong dilution of the “sepia” color), for octopuses it is black, for squids it is brown.

The ink is produced by a special organ - the pear-shaped outgrowth of the rectum. It's called an ink bag. This is a dense bubble, divided by a partition into two parts. The upper half is reserved for a spare tank, it stores ink, the lower half is filled with the tissues of the gland itself. Her cells are stuffed with grains of black paint. Old cells are gradually destroyed, their paint dissolves in the juices of the gland - ink is obtained. They enter the "warehouse" - they are pumped into the upper vial, where they are stored until the first alarm.

Not all contents of the ink sac are ejected at once. An ordinary octopus can put a "smoke screen" six times in a row, and after half an hour it completely restores all the spent ink. The coloring power of the ink liquid is unusually great. In five seconds, a cuttlefish paints all the water in a tank with a capacity of five and a half thousand liters with ejected ink.

And giant squids spew so much inky liquid from the funnel that the sea waves become cloudy in a space of a hundred meters!

Cephalopods are born with a sac filled with ink. One almost microscopic baby cuttlefish, barely getting out of the egg shell, immediately colored the water with five ink volleys.

And here is what an unexpected discovery was made by biologists in the last decade. It turned out that the traditional idea of ​​the "smoke screen" of cephalopods should be thoroughly revised. Observations have shown that the ink thrown out by cephalopods does not dissolve immediately, not before they stumble upon something. For a long time, up to ten minutes or more, they hang in the water as a dark and compact drop. But the most striking thing is that the shape of the drop resembles the outlines of the animal that threw it out. The predator, instead of the fleeing victim, grabs this drop. That's when it "explodes" and envelops the enemy in a dark cloud. The shark is completely confused when a flock of squid simultaneously, like from a multi-barreled mortar, throws out a whole series of "ink bombs". She rushes back and forth, grabs one imaginary squid after another, and soon everything is hidden in a thick cloud of ink scattered by her.

The zoologist put the squid in a tub and tried to catch it with his hand. When his fingers were inches from the target, the squid suddenly darkened and seemed to Hal to freeze in place. In the next moment, Hal grabbed... an ink mock-up that fell apart in his hands. The deceiver swam at the other end of the tub. Hal tried again, but now he kept a close eye on the squid. When his hand approached again, the squid darkened again, threw out the "bomb" and immediately became deathly pale, then darted invisible to the far end of the tub.

What a subtle maneuver! Squid did not just leave his image instead of himself. No, it's a dressing up scene. At first, it attracts the attention of the enemy with a sharp change in color. Then he immediately replaces himself with another dark spot - the predator automatically fixes his gaze on it - and disappears from the scene, having changed his outfit. Please note: now his color is not black, but white.

Cunning on inventions of nature.

Octopuses are a class of cephalopods. (Cephalopoda) known for their intelligence, the uncanny ability to merge with environment, a unique style of movement (jet propulsion), as well as splashing ink. On the following slides, you will discover 10 fascinating facts about octopuses.

1. Octopuses are divided into two main suborders

We know about 300 living species of octopuses, which are divided into two main groups (suborders): 1) finned or deep-sea octopuses (Cirrina) and 2) finless or true octopuses (Incirrina). The fins are characterized by the presence of two fins on the head and a small inner shell. In addition, they have antennae on their arms (tentacles) near each sucker, which may play a role in feeding. Finless, includes many of the most famous species of octopus, most of which are bottom-dwelling.

2 Octopus Tentacles Are Called Arms

The average person won't be able to tell the difference between tentacles and arms, but marine biologists clearly separate the two. The arms of cephalopods are covered with suckers along their entire length, and the tentacles have suckers only at the tips and serve to capture food. By this standard, most octopuses have eight arms and no tentacles, while the other two orders of cephalopods, cuttlefish and squid, have eight arms and two tentacles.

3. Octopuses release ink to protect themselves.

When threatened by predators, most octopuses release a thick cloud of black ink made up of melanin (the same pigment that affects the color of our skin and hair). You might think that the cloud merely serves as a visual distraction to buy the octopuses time to escape, but it also affects predators' sense of smell (sharks that can smell hundreds of meters away are particularly vulnerable to this olfactory attack).

4 Octopuses Are Extremely Intelligent

Octopuses are the only marine animals, other than whales and pinnipeds, that are capable of solving certain problems and recognizing various patterns. But regardless of the intelligence level of octopuses, it is very different from human: 70% of octopus neurons are located along the entire length of their arms, not in the brain, and there is no conclusive evidence that these are able to communicate with each other.

5. Octopuses have three hearts

All vertebrates have one heart, but octopuses are equipped with three: one pumps blood throughout the octopus's body (including the animal's arms), and two distill blood through the gills, with which they breathe underwater. There is another key difference from vertebrates: the main component of octopus blood is hemocyanin, which contains copper atoms, and not iron-containing hemoglobin, which explains the blue color of octopus blood.

6 Octopuses Use Three Ways To Move

A bit like an underwater sports car, the octopus moves in three different ways. If there is no need to hurry, they walk along the ocean floor using their flexible tentacle arms. To move faster underwater, they actively swim in the right direction by bending their arms and body. In the event of a real rush (for example, attacking a hungry shark), octopuses use jet propulsion, ejecting a jet of water (and ink to disorientate the predator) from the body cavity and away, as quickly as possible.

7. Octopuses are masters of disguise

Octopus skin is covered with three types of specialized cells that can quickly change color, reflectivity, and transparency, allowing the animals to blend in with their surroundings. Pigment-containing cells - chromatophores, are responsible for the red, orange, yellow, brown, white and black colors of the skin, and also give it shine, which is ideal for masking. Thanks to this arsenal of cells, some octopuses are able to disguise themselves as algae!

8. Giant octopus, considered the largest species of octopus

Forget all the movies about octopus monsters with tentacles as thick as tree trunks that sweep helpless sailors overboard and drown them. big ships. The biggest known species octopus - giant octopus (Enteroctopus dofleini), on average weighs about 15 kg, and the arms (tentacles) are about 3-4 m long. However, there is some doubtful evidence of significantly large individuals giant octopus, weighing more than 200 kg.

9 Octopuses Have A Very Short Lifespan

You may want to consider buying an octopus as a pet, for the reason that most species have a lifespan of about a year. Evolution has programmed male octopuses to die a few weeks after mating, and females stop feeding while waiting for eggs to hatch, and often starve to death. Even if you spay your octopuses (probably not every veterinarian in your city specializes in such operations), it is unlikely that your pet will live longer than a hamster or gerbil mouse.

10. The octopus squad has another name.

You may have noticed that in this article only one term "octopuses" was used, which is familiar to everyone and does not hurt the ear. But this detachment of cephalopods is also known as the octopus (octopus in Greek means "eight legs").

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The common octopus (Octopus vulgaris) is the most famous member of the cephalopod molluscs. This order includes 180 different species. All of them are united appearance, body structure and habitat features. Octopuses are found in both tropical and cold seas. Large octopuses are sometimes called octopuses.
Like any other shellfish, the octopus has a soft, boneless body that is sac-shaped. The leg, characteristic of molluscs, has been transformed into 8 tentacles with suckers along inner surface. Its head with two large spherical eyes (in a giant octopus, the eye can reach 40 cm in diameter) smoothly turns into tentacles. With their help, the mollusk moves, climbs underwater rocks and captures prey.
In addition to vision, octopuses have a well-developed sense of touch and smell. In their travels along the seabed, octopuses rely mainly on the sense of smell - eyes in muddy water can let down. But these animals do not hear very well: it is believed that they react only to very loud sounds.

Naturalist's Notes
Let's watch the octopus in its native element - the deep sea, among the coral reefs, illuminated by the faint greenish light of the distant sun.
Here he lurks at the bottom, tucking his tentacles under him. It almost merges with the sandy bottom. Octopuses are able to change color and do it more skillfully and faster than chameleons! If the octopus wants to scare away the enemy, then it quickly changes colors, and if it is annoyed, it fills with crimson colors. It's all about the pigment cells of the octopus skin. Different cells contain different pigments, and the subcutaneous muscles can stretch and compress the pigment cells. When all cells are compressed - the octopus is pale, when cells with a certain pigment are stretched, then the granules of their pigment occupy much large area than in the compressed state, and thus form the color of the octopus.
A crab appears from a small crevice in the reef and walks slowly, rearranging its stilted legs. Carefully lowering the claw into the bottom silt, he fishes out small worms and sends them to his mouth.
The octopus spots its prey. Easily "fluttering" from the bottom, he grabs her with his movable tentacles. The crab's attempts to defend itself with a huge claw are unsuccessful: the octopus squeezes it, breaks off the claw and bites the victim's shell. When he sets sail from this place, only a few pieces of crab shell remain on the sand.
Octopuses are the most intelligent among invertebrates: they can distinguish colors, shapes. The uniqueness of octopuses was confirmed by his research by the Dutch biologist Tan-Kot.
But suddenly the plot changes, and the octopus turns from a hunter into a potential victim. A moray eel emerges from a small grotto in the reef! This predator induces simply panic fear on the octopus. The mollusk freezes and is afraid to move, hoping to go unnoticed. But the moray eel does not have to look at the octopus - it easily finds it by smell. It prepares for defense: it turns sharply black, and then suddenly “jumps” to the side, shooting a jet of water. He covers his maneuver with the release of an "ink bomb" - a jet of thick black liquid.
What does she represent? This liquid secret weapon of all cephalopods, produces a special organ - a pear-shaped outgrowth of the rectum. It's called an ink bag. As soon as cephalopod gets into danger, immediately shoots out ink. Moreover, he can shoot several times in a row (five or six), then the ink supply ends, and after half an hour it is restored.
These inks are unique weapon: they not only create a "smoke screen", but contain special substances that completely discourage the sense of smell in fish. But not so long ago it turned out that the ink thrown out of the bag is not just a "smoke screen"! They take a shape resembling an octopus. At the same time, the octopus immediately turns pale and hides after the release of ink. And the predator takes the ink for the prey being pursued!
Having released the ink, the octopus falls like a stone to the bottom. Murena, rushing after him, falls straight into the ink cloud. Having sailed through it, she rushes in search of a mollusk, but cannot find it: her sense of smell "does not work", she does not smell the octopus at all, although she is very close to it.
But what if the octopus was not lucky and he did not manage to escape from the moray eel? In this case, he would part with the tentacle that the predator grabbed - let him bite off, it's not a pity. The octopus, like other cephalopods, has the ability to regenerate - restore lost limbs.
Our octopus continues its journey along the seabed. He looks into different caves, looking for something, but does not find it. Finally, he discovers a suitable grotto, spacious, with a narrow entrance into which the predator cannot squeeze through (and the octopus itself can crawl through any crack).
In the grotto, the octopus - it's time to say that this is a female - puts things in order: it takes out small pebbles, and with larger stones and shells “barricades” the entrance. Tired, she falls asleep - tucking her tentacles under her, she freezes at the bottom of the grotto. But one pair of her tentacles does not sleep, but remains elevated - "follows" what is happening. These "locators" will catch even the slightest fluctuation in the water.
After a short rest, the female begins to lay eggs. In a basket woven from her tentacles, she places small gelatinous lumps of caviar. Now she will not even have time for food - she will zealously guard and care for her offspring. With tentacles, the female gently cleans the masonry, with suction cups, like a vacuum cleaner, removing debris from the eggs. And as soon as the little octopuses appear and spread out in different directions, the mother octopus will die...