Octopus

The body of the octopus is short, soft, oval in the back. The mouth opening is located at the place where its tentacles meet, and the anal opening opens under the mantle . The mantle resembles a wrinkled leather bag. The octopus's mouth is equipped with two powerful jaws that look like a beak of a parrot . In the throat there is a grater ( radula ), which grinds food.

The head carries eight long tentacles - “hands”. "Hands" are interconnected by a thin membrane and have from one to three rows of suction cups. On all eight tentacles of an adult octopus there are about 2000 of them, each of which has a holding power of about 100 g, and, unlike human ones, the octopus suckers require effort in holding, and not in suction, that is, they are held only by muscular effort.

The octopus has three hearts : one (the main) drives blue blood throughout the body, and the other two - gill - push blood through the gills.

Some species of octopus are poisonous. Blue-ringed octopuses (several species from the genus Hapalochlaena ; English Blue-ringed octopus ), living on the western shores of the Pacific Ocean, are among the most poisonous animals in the world ^[2] .

Octopuses have an unusual ability - due to the lack of a skeleton, they can change shape. For example, some octopuses during hunting are flattened at the bottom, disguising themselves as a flounder. The ability of octopuses to penetrate through surprisingly small holes is known.

Nervous system and sensory organs

The brain of an octopus is highly developed (one of the most developed among invertebrates), has an embryonic cortex. The ring covers the esophagus ^[3] . The eyes are large, with a lens similar to a human (however, the retina , unlike the human, is not inverted: the photoreceptors are directed towards the light ^{[4] [5]} ). The pupil is rectangular.

Octopuses are capable of perceiving sound , including infrasound . On each "arm" there are up to ten thousand taste buds that determine the edibility or inedibility of the subject.

In 2015, the decoding of the octopus genome Octopus bimaculoides was announced . It turned out to be almost as large as the human one : 2.7 billion base pairs (in humans - 3.1 billion). This is quite a lot for invertebrates, although not a record. The octopus coding for the proteins of the genes is about 34 thousand (while in humans - less than 25 thousand) ^{[6] [7]} .

The number of chromosomes is known, in particular, for Octopus vulgaris (2n = 60), O. variabilis ( O. minor ; 2n = 56), O. ocellatus (2n = 60) ^[8] .

An ordinary octopus has the ability to change color, adapting to the environment . This is explained by the presence in his skin of cells with various pigments ^[9] , which, under the influence of impulses from the central nervous system, can stretch or contract depending on the perception of the senses. The usual color is brown. If the octopus is scared, it turns white, if angry, it blushes.

The length of adults varies from 1 centimeter (in males of the species Argonauta argo ) to 4 meters (in Haliphron atlanticus ). The mass of octopus reaches 50 kg. There is evidence that the Doflein octopus can reach a length of 960 cm and a mass of 270 kg.

Rarely exceeds 5 years, an average of 1-3 years.

They live in all tropical and subtropical seas and oceans, from shallow water to a depth of 100-150 m. They prefer rocky coastal zones, looking for caves and crevices in the rocks for habitation.

Predators They eat mollusks , crustaceans , fish . An ordinary octopus captures prey with all eight tentacles. The octopus with its beak bites the victim, holding it with suction cups. In this case, the salivary gland venom from the pharynx enters the victim's wound. Strongly expressed individual preferences in food and in the method of obtaining it.

Most species of octopus lead a benthic lifestyle, living among stones, rocks and algae. In the Far East, the favorite shelter of young animals is the empty shells of the seaside scallop. In the afternoon, octopuses are less active than at night, so they are considered nocturnal animals.

On a hard surface (including a sheer surface), the octopus moves crawling using tentacles with suction cups. It can also swim tentacles backward, setting itself in motion by a kind of jet propulsion device - collecting water into the cavity in which the gills are located and with force pushing it in the direction opposite to the movement through the funnel , which plays the role of a nozzle . The direction of movement changes by turning the funnel. Both ways of moving the octopus are rather slow: when swimming, it is inferior in speed to the fish. Therefore, the octopus prefers to hunt from an ambush, mimicking the environment, and trying to hide from its pursuers ^[10] .

Thanks to the soft, flexible body, octopuses can penetrate through holes and crevices, much smaller than the usual sizes of their bodies, which allows them to hide in sophisticated shelters in all sorts of ways. They even settle in crates, cans, car tires and rubber boots. They prefer shelters with a narrow entrance and a spacious room. They keep their dwellings clean: they “sweep” them with a stream of water from a funnel, put the leftovers outside in a garbage heap. At the approach of enemies (including divers or scuba divers ) they flee, hiding in crevices of rocks and under stones.

As they flee, octopuses of many kinds produce trickles of ink - a dark liquid produced by special glands. This liquid hangs in water in the form of shapeless translucent spots and for some time keeps compact until it is washed out by water. Zoologists have not yet reached a consensus on the purpose of this behavior. Cousteau suggested in the book “In the World of Silence” that these spots are a kind of false goal, designed to distract the attention of the attacker and allow the octopus to gain time to hide ^[11] .

Octopuses have a way of protection - autotomy : the tentacle captured by the enemy can come off due to a strong contraction of the muscles, which in this case break themselves. The torn tentacle for some time continues to move and respond to tactile stimuli, which serves as an additional distraction for the predator chasing the octopus ^[12] .

Many species winter in deeper waters, and in summer migrate to shallow water.

Many zoopsychologists consider octopuses to be the most “intelligent” among all invertebrates in many respects: they can be trained, have good memory, distinguish geometric shapes - they distinguish a small square from a larger one; a rectangle positioned vertically from a rectangle positioned horizontally; circle from a square, rhombus from a triangle. They recognize people, get used to those who feed them. If you spend enough time with the octopus, it becomes tame. Well trained ^[13] . However, discussions about the rationality of octopuses continue ^{[14] [15] [16]} .

Single, territorial. Often settles next to octopuses of the same size.

The nest is a hole in the ground, lined with a shaft of stones and shells. Ball-shaped eggs, connected in groups of 8-20 pieces. After fertilization, the female arranges a nest in a hole or cave in shallow water, where it lays up to 80 thousand eggs. The female always takes care of the eggs: she constantly ventilates them, washing them with a stream of water from the siphon . With tentacles, she removes foreign objects and dirt. During the entire period of development of eggs, the female remains at the nest without food and often dies after hatching juveniles. Females of deep-sea octopuses spend several years near the clutch, since eggs develop especially long because of the low water temperature ^[17] .

Eating octopus is common in many cultures. In Japanese cuisine, octopus is a common product from which dishes such as sushi and takoyaki are prepared . They are also eaten alive. Live octopuses are cut into thin pieces and eaten for several minutes, while the tentacle muscles continue to convulse.

Octopuses eat in the Hawaiian Islands . Octopuses are often used in Mediterranean cuisine . At present, octopuses in salted-dried form and as part of sea cocktails in brine are also widespread in Russia.

Octopus is a source of vitamins B ₃ , B ₁₂ , potassium , phosphorus and selenium . Cook octopuses carefully to get rid of mucus, odor and ink residue.

The ink of octopuses and other cephalopods is in demand among artists for their durability and beautiful brown tone (known as “ sepia ”, which came from the ancient Greek name for cuttlefish ) ^[18] .

^[nineteen]

• Childbirth incertae sedis
  • † Genus Paleocirroteuthis
  • † Genus Proteroctopus
  • † Genus Styletoctopus
• † Family Palaeoctopodidae
  • † Genus Keuppia
  • † Genus Palaeoctopus
• Suborder Cirrina
• Suborder Incirrina
  • Superfamily Argonautoidea
  • Superfamily Octopodoidea

Before the invention of scuba gear , which made it possible to observe the life of marine life in natural conditions, knowledge about their lifestyle and behavior was quite limited. In that era of octopuses, the idea was formed of ferocious, treacherous and extremely dangerous animals. The reason for this was probably their frightening appearance: serpentine tentacles, the gaze of large eyes, suckers, serving (as was mistakenly thought) to suck blood from the victims. The responsibility for the death of people in the sea under unclear circumstances was often assigned to octopuses. The human imagination gave rise to tales of giant octopuses that could not only kill a man, but also sink a large sailing ship.

The words "octopus" and "octopus" have become common metaphors for organizations representing public danger: the mafia , monopoly , secret societies, totalitarian sects and the like (for example, the television series " Octopus ").

The negative attitude towards octopuses is reflected in fiction. Victor Hugo in the novel " Workers of the Sea " (1866) colorful, but inaccurately describes the octopus as a living embodiment of absolute evil:

With many vile mouths this creature comes to you; the hydra merges with the person, the person merges with the hydra. You are one with her. You are a captive of this embodied nightmare. A tiger can gobble you up, an octopus - it's scary to think! - sucks you. He pulls you toward him, draws you in, and, bound, glued together by this living mucus, helpless, you feel how slowly you spill over into a terrible bag, which this monster is.

It is terrible to be eaten alive, but there is something even more indescribable - to be drunk alive.

Octopuses were somewhat rehabilitated with the spread of scuba gear. Jacques Yves Cousteau , who was one of the first to observe octopuses in their natural habitat, in his book “ In the World of Silence ” describes the first attempts to get acquainted with these creatures:

It was this idea of ​​an octopus that dominated us when we first entered the underwater world. However, after the first meetings with the octopus, we decided that the words "drunk alive" are applicable more to the condition of the author of the passage, than to the person who met the octopus in practice.

Countless times we have exposed our own individuals to the risk of becoming a victim of the addiction of octopus to unusual drinks. At first, we felt a natural disgust at the thought of the need to touch the mucous surface of rocks or marine animals, but quickly became convinced that our fingers are not so scrupulous in this regard. So, for the first time, we decided to touch the living octopus. And there were many around and on the bottom, and on the rocky slopes. Once Dumas gathered courage and took the bull by the horns, in other words, removed the octopus from the cliff. He did this not without fear, but he was reassured by the fact that the octopus was small, and Dumas clearly represented a gulp too big for him. But if Didi was a little cowardly, then the octopus itself was just in a panic. He wriggled desperately, trying to save himself from the four-armed monster, and finally broke free. The octopus flew away irregularly, pumping water through itself and throwing out trickles of its famous ink liquid.

Soon we were boldly approaching cephalopods of any size.

There is no reliable evidence of an octopus attacking a person, nevertheless, certain species pose a serious danger because of the poisonous bites on which a person can provoke them, persistently trying to get in touch with them.

In 1814, Japanese artist Katsushika Hokusai published an erotic engraving called “The Dream of a Fisherman's Wife, ” which depicts two octopuses and a woman. Engraving has gained great fame throughout the world and over the centuries ^[20] .

In the second episode of the television movie Wild Future (100 million years into the future) there are swamps - the land descendants of octopuses.

The image of the octopus sucking out the brain was used in the first episodes of the 4th season of the television series “ Grimm ”.

The image of funny harmless playful octopus children was used in the Soviet cartoon " Octopuses ", based on the poem by Eduard Uspensky's "Jolly Family".

Squidward is an octopus from the American animated series SpongeBob SquarePants .

Fans of the Detroit Red Wings NHL hockey club have a tradition that originated in 1952 - throwing octopuses on ice in the Stanley Cup playoffs , eight clam limbs, according to the fans, symbolized eight victories that had to be gained to win the trophy ^{[21 ]} .

• Octopus Paul
• Fighting octopus

• Sai Montgomery. The soul of an octopus. Secrets of consciousness of an amazing creature = Montgomery Sy. The Soul of an Octopus: A Surprising Exploration into the Wonder of Consciousness. - M .: Alpina Non-fiction, 2018 .-- 317 p. - ISBN 978-5-91671-827-0 .