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Octopus is a well-known cephalopod, distributed in almost all seas and oceans. These amazing animals can take on different shapes and colors, camouflaging themselves with their surroundings. Octopuses are valued among people due to their taste, which is why today there are entire farms for breeding these animals.
Origin of the species and description
Photo: Octopus
Octopuses (aka octopuses) are the most common representatives of the cephalopod order. Theutologists, scientists who study octopuses, distinguish two main orders that differ in their way of life: benthic and nomadic. For the most part, octopuses are bottom-dwelling creatures.
The body of an octopus consists entirely of soft tissue, therefore, in terms of paleontology, research on the origin of octopuses is difficult - after death, they immediately decompose, leaving no traces in the layer. However, European paleontologists discovered the remains of an octopus imprinted in the once soft soil rocks in Lebanon.
Video: Octopus
These traces were left approximately 95 million years ago. The remains of these octopuses are in no way different from modern octopuses - the prints were accurate, right down to the structure of the stomach. There are also other types of fossil octopuses, but the sensational discovery revealed that octopuses have not changed over millions of years of existence.
The following representatives also belong to the order of cephalopods:
- nautiluses;
- cuttlefish;
- squid.
Interesting fact: Squids are the largest representatives of cephalopods. In 2007, a female colossal squid was caught that weighed about 500 kg.
The name “cephalopod” was not obtained by chance: several (usually eight) tentacle limbs grow from the head of a representative of the order. It is also common that cephalopods do not have chitinous shells or have a very thin chitinous coating, which in no way protects them from external influences.
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Perhaps one of the most important features of their tentacles is the presence of suckers. These suckers are made of tiny complex muscles, making them more complex than regular suckers. They can apply intense pressure, enough to tear flesh. They are also very sticky. In the case of the giant octopus, one of its suction cups can lift an object weighing up to 16 kg.
Appearance and features
Photo: Giant octopus
Octopuses are made entirely of soft tissue. Its “head” has an oval shape, from which eight movable tentacles grow. The mouth with jaws that resemble the beak of a bird is located at the point where all the tentacles converge - the octopuses grab the victim and pull it into its center. The anus is located under the mantle, a leathery sac behind the squid.
The octopus's pharynx is ribbed, called the “radula,” and functions as a grater for food. The octopus' tentacles are connected by a thin, stretchy membrane. Depending on the size of the octopus, its tentacles may have one or three rows of suckers. An adult octopus has a total of about 2 thousand suckers, each of which can hold about 100 grams of weight.
Interesting fact: Octopus suction cups do not work like man-made suction cups - in a vacuum. The octopus attaches itself using muscle effort.
The octopus is also interesting because it has three hearts. The first drives blood throughout the body, and the other two hearts act as gills, pushing blood through for respiration. Some species of octopus have poison, and blue-ringed octopuses, which live on the Pacific coast, are ranked among the most poisonous animals in the world.
Fun fact: Octopuses have blue blood.
Octopuses have absolutely no bones or any kind of frame, which allows them to freely change shape. They can spread out along the bottom and disguise themselves as sand, or they can climb into the neck of a bottle or a narrow crevice in the rocks. Octopuses are also capable of changing their color to suit their environment.
Octopuses vary in size. The smallest representatives can reach a length of 1 cm, the largest - (Doflein's octopus) - 960 cm with a mass of 270 kg.
№3
Like squids, they have three hearts. One main, three-chamber and two smaller ones. The main heart pumps blood throughout the body. The two smaller ones are located near the gills (they are called gill hearts). These hearts oxygenate the blood before it reaches the main heart. The main heart then delivers oxygenated blood to all organs.
Where does the octopus live?
Photo: Octopus in the sea
They can be found in the warm waters of seas and oceans at various depths.
Octopuses choose the following places for comfortable settlement:
- deep bottom, where it comfortably disguises itself as stones and sand;
- sunken objects with many secluded places;
- reefs;
- rocks.
Octopuses hide in small crevices and secluded places, and can also hunt there. Sometimes an octopus can climb into a shell left by crustaceans and sit there, but octopuses themselves never establish permanent homes.
The maximum depth at which octopuses can comfortably live is 150 m, although deep-sea representatives of the genus can descend 5 thousand meters down, like squid. Occasionally, octopuses can be found in cold waters, where they behave extremely sleepy.
They are considered to be nocturnal creatures, since during the daytime they hide in their shelters. Occasionally, being half asleep, an octopus can grab prey swimming by and, almost without waking up, eat it.
Octopuses can swim, although they don't like to do so - swimming creates a vulnerable situation where the octopus is easy to grab. Therefore, they move along the bottom using tentacles. There are no obstacles for octopuses in the form of steep rocks and vertical surfaces - the octopus makes its way along them using suction cups and grabbing onto any objects with its tentacles.
When swimming, they move slowly because they use the cuttlefish method: they take water into their mouth and push it out. Due to their slowness, they mostly hide in shelters and move when absolutely necessary.
Video
And finally, an interesting documentary about octopuses from National Geographic.
Author: Pavel Chaika, editor-in-chief of Poznavaika magazine
When writing the article, I tried to make it as interesting, useful and high-quality as possible. I would be grateful for any feedback and constructive criticism in the form of comments on the article. You can also write your wish/question/suggestion to my email [email protected] or Facebook, with respect, the author.
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What does an octopus eat?
Photo: Big octopus
Octopuses are convinced predators that are capable of swallowing almost any prey, even those larger than themselves. A hungry octopus waits patiently in a secluded place, changing its color to camouflage. When prey swims by, it makes a sharp lunge, trying to grab it with all its tentacles at once.
Speed is very important in this matter - a strong opponent can break free of his grip. Therefore, the octopus immediately pulls the prey into its mouth. Its beak bites the victim if it does not fit into the mouth, and the pharynx performs a chewing function - it crushes food into small pieces.
Interesting fact: Poisonous octopuses extremely rarely use poison to kill prey - this is more of a defense mechanism than an adaptation for hunting.
Most often, octopuses feed on the following representatives of the ocean fauna:
- any fish, including poisonous ones;
- crustaceans, which sometimes give serious resistance to octopuses;
- the octopus's favorite delicacy is lobsters, lobsters and crayfish, which, upon seeing a formidable predator, strive to swim away from it as quickly as possible;
- sometimes large octopuses can catch a small shark;
- Cannibalism is not a rare phenomenon among octopuses. Stronger individuals often eat smaller ones.
There are times when an octopus does not calculate its strength when attacking a particular victim, or a predatory fish itself tries to eat the octopus. Then a fight ensues, in which the octopus may lose a tentacle. But octopuses are weakly susceptible to pain, and their tentacles grow quickly.
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The blue-ringed octopus may look beautiful, but appearances are deceiving. The blue-ringed octopus is a highly aggressive and venomous genus. The genus contains three species. They are considered one of the most poisonous animals on the planet. Despite its small size (approximately 20 cm), its venom is so toxic that one bite is enough to kill a person. One blue-ringed octopus has enough venom to kill 26 people. What makes its bite more dangerous is that there is still no antidote, and the bite is often invisible, so the victim does not even suspect that the most dangerous poison on the planet has entered his body.
Features of character and lifestyle
Photo: Sea octopus
Octopuses are dedicated loners, very attached to their territory. They lead a sluggish, sedentary lifestyle, running from place to place only when necessary: when there is not enough food in the old territory, when enemies have appeared around, or when they are looking for a partner.
Octopuses consider each other competitors, so one octopus tries to avoid the territory in which another octopus lives. If a collision does occur and the trespasser is in no hurry to leave, a fight may occur in which one octopus risks being injured or eaten. But such collisions are extremely rare.
During the day, octopuses hide in a shelter, and at night they go out into more open spaces to hunt. Octopuses like to choose various traces of human activity as a home: boxes, bottles, car tires, etc. They live in such houses for a long time. There is cleanliness around the octopus's house: they remove excess debris and dead algae, as if sweeping the surroundings with a stream of water. They put leftovers and garbage in a separate pile.
In the winter, octopuses descend to the depths, in the summer they live in shallow water, and they can sometimes be found on the shore - octopuses are often thrown out by waves.
Nutrition
Octopuses, however, like other cephalopods, are predatory creatures; their diet consists of a variety of small fish, as well as crabs and lobsters. They first capture their prey with their tentacles and kill them with poison, then they begin to absorb them, since they cannot swallow whole pieces, they first grind the food with their beak.
Social structure and reproduction
Photo: Little octopus
Twice a year, the female begins to look for a male to mate with. They form a strong couple and find a home together, which they arrange in such a way that it is comfortable to keep an eye on the eggs. Typically, such housing is located in shallow waters.
Octopuses do not have courtship and fights for a female. The female herself chooses the male with whom she wants to have offspring: due to her lazy lifestyle, this is usually the closest male she can find.
The female lays about 80 thousand eggs. She stays with the offspring and zealously protects the clutch. The incubation period lasts 4-5 months, during which the female does not go out hunting, becomes completely exhausted and, as a rule, dies from exhaustion by the time her children appear. The male also takes part in the life of future children, protecting the female and eggs, as well as removing dirt and all kinds of debris from them.
After emergence, the larvae are left to their own devices; for the first two months they eat plankton and swim with the current. Thus, they often become food for cetaceans that feed on plankton. At two months the larva becomes an adult and begins to lead a bottom-dwelling lifestyle. Rapid growth allows many individuals to survive. At the age of four months, an individual octopus can weigh 1-2 kilograms. In total, octopuses live 1-2 years, males live up to 4 years.
Interesting Facts
Natural enemies of the octopus
Photo: Octopus
Among the natural enemies of the octopus, we can distinguish those who pose the greatest danger to it:
- sharks, including reef sharks;
- seals, sea lions and fur seals;
- dolphins and killer whales often play with octopuses, eventually eating them or leaving them alive;
- some large fish.
If an octopus is found by a predator in a state of secrecy, the first thing it will do is try to swim away. Many species release clouds of ink at the enemy and then swim away - this is how the octopus buys time until the enemy sees it or is in a state of shock. Also, for the purpose of self-preservation, octopuses hide in narrow crevices and wait until the enemy leaves.
Another unique way of protecting the octopus is autotomy. When the enemy grabs the creature by the tentacle, the octopus deliberately detaches it from the body and flees. This is similar to how a lizard sheds its tail if it is grabbed by it. The tentacle subsequently grows back.
Interesting fact: Some octopuses have been observed engaging in autocannibalism—eating their own tentacles. This is due to a disease of the nervous system, in which the octopus, experiencing the slightest hunger, eats the first thing that, literally, “comes to hand.”
Scientists believe that octopuses are the most intelligent species of invertebrates. They show intelligence and observation in all kinds of experiments. For example, octopuses can open jars and primitive latches; Individual octopuses are able to put cubes and circles into certain holes that match in shape. The high intelligence of these creatures makes them rare prey for marine life, most of which do not have this indicator.
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What organ is similar in structure to humans and octopuses?
When studying the animal, a striking similarity between the eyes of an octopus and a human was revealed. The so-called convergent similarity (common characteristics in organisms of different systematic groups) is expressed in the presence of:
- retina;
- lens (in a cephalopod it is more rounded due to different degrees of refraction of light in air and water);
- pupil (has a rectangular shape);
- iris;
- cornea.
Octopuses can also focus their vision on objects located at different distances, but focusing in them occurs not due to a change in the curvature of the lens, but by bringing it closer or further to the retina.
