The octopus is a representative of the order of marine mollusks belonging to the class of cephalopods. All individuals are characterized by a saccular body. Further in the article we will find out the features of these animals, how many octopus have legs. Photos of the mollusks will also be given below.
Short description
The octopus has three hearts. The main thing is driving blood over the body. The rest push her through the gills. Due to the fact that hemocyanin is present in plasma and red blood cells (copper replaces iron in it) instead of hemoglobin, the blood in animals is blue. The octopus has large eyes with a rectangular pupil. The head of the animal is well developed, has a cartilaginous skull. It provides protection to the brain with the rudimentary cortex. The size of the animal is from 50 mm to 9.8 m (between the ends of the tentacles located opposite).
Nutrition
All octopuses are predators. Their main food is crustaceans, fish, and mollusks. An ordinary octopus captures prey with all its tentacles. Holding the victim with suction cups, he bites it with his beak. Venom from the salivary glands enters the wound of prey. Octopuses are characterized by pronounced individual preferences in food and methods of obtaining it. The mollusk has four pairs of tentacles. We will find out how many legs an octopus has and whether it has hands.
Shellfish in motion
Most species live among stones, algae and rocks. The favorite shelter of 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 at all? On solid, including steep surfaces, mollusks move crawling. All tentacles are involved. Many people think that an octopus has eight legs. However, this is not quite true. During research it was found that the mollusk is repelled by two tentacles. To move forward, he uses the rest of the limbs. Hand movements are similar to those made by swimmers. A pair of hind limbs is used to move along the seabed. With their help, the mollusk also climbs on underwater rocks. Thus, the number of legs of an octopus is 2, all other tentacles serve as hands. Due to the fact that the body of the mollusks is elastic, they can penetrate through cracks and holes, the sizes of which are much smaller than their own. This allows them to hide in all kinds of shelters.
Behavior
Many species have special glands that produce a dark fluid called "ink." In the form of translucent shapeless spots, the liquid hangs in water and keeps compact for some time before it is washed out by water. Fleeing from someone fleeing, an octopus releases trickles of ink. Zoologists today do not have a consensus on the purpose of this behavior. Researcher Cousteau hypothesized that the "ink spots" of octopuses are in some ways false targets for opponents, distracting their attention. The mollusks have another device for protection. The tentacle of the mollusk captured by the enemy can come off. This is due to strong muscle contraction. For some time, the detached tentacle continues to respond to tactile stimuli and move. This is another additional distraction for those who are chasing an octopus.
Research
For a very long time there was no exact answer to the question of how many legs an octopus has. Biologists from more than twenty European centers that study marine life have been observing octopus behavior for a long time. About two thousand data were analyzed. Studies have shown 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. Researchers note that the brain sends a signal to the beginning of movement, but each tentacle makes a decision on its speed, nature and direction. Moreover, even those limbs that are torn from the body continue to perform the actions programmed earlier. Biologists also found that the octopus is equally good at limbs of the left and right sides of the body. However, preference is still given to the third front tentacle - it is intended to bring food to the mouth. Each limb has up to 10 thousand receptors, through which the inedibility or edibility of an object is determined.
Features
After finding out how many legs the octopus has and how it uses its limbs, the researchers began to study the intelligence of animals. Zoopsychologists consider these mollusks the most intelligent of all representatives of invertebrates. Such conclusions are based on practical observations. So, cephalopods have a good memory, can be trained, can distinguish geometric shapes: large from small, circle from square, vertical rectangle from horizontal. In addition, they get used to people, easily recognize those who feed them. If you spend a lot of time with the octopus, then it will become tame. These mollusks are highly trained.