Marine life. Octopus. Description, features. How many legs does an octopus have?

Octopus is a representative of a group of marine mollusks belonging to the class of cephalopods. For all individuals, a sack-like body is characteristic. Further in the article we will find out the features of these animals, how many octopus legs. Photos of shellfish will also be given below.

Short description

The octopus has three hearts. The main thing is the blood over the body. The rest push it through the gills. Because hemocyanin is present in the plasma and red blood cells (in it copper replaces iron) instead of hemoglobin, the blood of the animals is blue. The octopus has large eyes with a rectangular pupil. The head of the animal is well developed, it has a cartilaginous skull. It provides protection to the brain with rudimentary bark. The size of the animal is from 50 mm to 9.8 m (between the ends of the tentacles opposite).

Food

All octopuses are predators. Their main food is crustaceans, fish, mollusks. Ordinary octopus captures prey with all its tentacles. Keeping suckers sacrifice, he bites her with his beak. The poison from the salivary glands gets into the wound of the prey. For octopuses are characterized by pronounced individual preferences in food and ways of obtaining it. The mollusk has four pairs of tentacles. How many legs the octopus has and whether it has hands, we will find out further.

Molluscs in motion

Most species live among rocks, algae and rocks. The favorite shelter for young animals in the Far East, for example, are empty scallop shells. Due to the fact that octopuses are very active at night, they are considered nocturnal animals. So, how many legs does an octopus have? How does he use his limbs? On hard, including steep surfaces, mollusks move crawling. In this case, all tentacles are involved. Many believe that the octopus has eight legs. However, this is not quite true. During the research it was found out that the mollusk was repelled by two tentacles. To move forward, he uses the rest of his limbs. Movement "hands" are similar to what swimmers do. A pair of hind limbs is used to move along the seabed. With their help, the clam also climbs on underwater rocks. Thus, the number of legs in the octopus is 2, all other tentacles perform the function of the hands. Due to the fact that the body of the mollusks is elastic, they can penetrate through the cracks and holes, the dimensions of which are much smaller than their own. This allows them to hide in all sorts of shelters.

Behavior

Many species have special glands that produce a dark liquid - "ink." In the form of semi-transparent shapeless spots, the liquid hangs in water and holds for a while compactly, before it is washed away by water. Escaping from someone to get away, the octopus lets out trickle of ink. Today zoologists have no common opinion on the purpose of this behavior. Researcher Cousteau hypothesized that the "ink spots" of octopuses are in some way false targets for opponents, distracting their attention. There are shells for another protection device. The tentacle of a clam seized by an enemy can come off. This is due to a strong muscle contraction. For some time, the severed tentacle continues to respond to tactile stimuli and move. This is another additional distraction for those pursuing the octopus.

Research

For a very long time there was no exact answer to the question of how many legs the octopus has. Biologists from more than twenty European centers dealing with the study of marine life observed the behavior of octopuses for a long time. About two thousand data were analyzed. In the course of research, it was found that two tentacles are definitely legs. As a rule, animals move slowly. But in case of danger, mollusks can reach speeds of up to 15 km / h. The researchers note that the brain sends a signal to the beginning of the movement, the decision on its speed, nature and direction each tentacle takes independently. In this case, even those limbs that are detached from the body, continue to perform the actions programmed earlier. Biologists also found that the octopus equally well knows the limbs of the left and right sides of the body. However, preference is still given to the third anterior tentacle - it is intended to bring food to the mouth. Each limb has up to 10,000 receptors, through which the inedibility or edibility of the object is determined.

Features

Finding out how many legs the octopus has and how it uses its limbs, the researchers have begun to study the intelligence of animals. Zoopsiologists consider these mollusks to be the most intelligent of all representatives of invertebrates. Such conclusions are based on practical observations. So, the cephalopods have good memory, they can be trained, they are able to distinguish geometric figures: large from small, circle from square, vertical rectangle from horizontal. In addition, they get used to people, they easily recognize those who feed them. If you spend a lot of time with an octopus, then it will become tame. These mollusks are perfectly trained.