How and what does the starfish eat: features, description and interesting facts

Echinoderms, which include the starfish, are representatives of a very special group. They do not look like anyone. These marine inhabitants cause a lot of questions, among which the following are of particular interest: "What does the starfish eat?", "For whom is it a mortal threat?".

Stars on the seabed

These extraordinary ornaments of the seabed exist on the planet long enough. They appeared about 450 million years ago. Allocate up to 1600 kinds of stars. These animals inhabit almost all the seas and oceans of the earth, the water of which is fairly salty. The stars do not tolerate desalinated water, they can not be found in the Azov and Caspian seas.

The rays in animals can be from 4 to 50, the sizes range from a few centimeters to a meter. The life expectancy is about 20 years.

Marine inhabitants do not have a brain, but each eye has an eye. The organs of vision resemble insects or crustaceans, a good distinction is between light and shadow. A lot of eyes help animals successfully hunt.

Breathe the stars almost through the skin, so they are very important enough oxygen in the water. Although some species can live on decent depths of the ocean.

Features of the structure

It is interesting how they reproduce, how the starfish feed. Biology classifies them as a class of invertebrate echinoderms. A starfish does not have blood as such. Instead, the heart of the star pumps through the vessels sea water, enriched with certain trace elements. Pumping water not only saturates the animal's cells, but also by injecting fluid in one or another place helps the star to move.

Starfish have a radial pattern of the structure of the skeleton - rays from the central part. The skeleton of sea beauties is unusual. It consists of calcite and develops inside a small sprocket made up of several calcareous cells. What and how the starfish feed, largely depends on the characteristics of their structure.

These echinoderms have on their tentacles special pedicellariae in the form of tweezers at each tip of the outgrowth. With their help, the stars hunt and clean their skins from the litter hammered between the needles.

Sly hunters

Many are interested in how the starfish feed. Briefly on the structure of their digestive system can be found below. These amazing beauties give the impression of perfect security. In fact, they are sea predators, gluttonous and insatiable. Their only drawback is the slow pace. Therefore prefer a motionless delicacy - shells of mollusks. With pleasure, the starfish feeds on the scallop, does not mind eating the sea urchin, trepanga, and even inadvertently swam too close to the fish.

The fact is that the starfish has almost two stomachs, one of which can be turned outward. The imprudent victim, caught by the pedicellaria, is transferred to the mouth opening in the center of the rays, then a stomach is poured over her like a net. After this, the hunter can release the prey and slowly digest it. Some time the fish even drags its executioner with him, but the victim can not escape. All that the starfish feeds is easily digested in her stomach.

She does a little differently with the shells: she slowly approaches the dish she likes, braids the shell with her rays, places her mouth in front of the shell slit and begins to open the doors.

It is necessary to appear at least a small gap, it immediately pushes the external stomach. Now the sea gourmet calmly digests the host of the shell, turning the mollusc into a jelly-like substance. Such a fate awaits any eaten sacrifice, it does not matter whether the starfish feeds on a scallop or small fish.

Features of the structure of the digestive system

The predator does not have any devices for capturing prey. The mouth, surrounded by a ring lip, connects to the stomach. This body occupies the entire interior of the disk and has high flexibility. A gap of 0.1 mm is enough to penetrate the shell sashes. In the center of the aboral side, a narrow, small intestine opens from the stomach. What the starfish feed on depends largely on the unusual structure of the digestive system.

Love of stars on the ocean floor

Most of the sea stars are of different sexes. For the time of love games, individuals are so busy with each other that they stop hunting and are forced to fast. But this is not fatal, because in one of the stomachs these cunning people tend to postpone the nutrients in advance for the duration of mating.

The sex glands are located near the stars near the base of the rays. When mating, the female and male individuals join the rays, as if merging in a gentle embrace. Most often, caviar and male germ cells enter the sea water, where fertilization takes place.

In case of shortage of these or that individuals, the stars can change the sex to maintain the population in a certain territory.

Caviar of these inhabitants of the sea is often left to itself until the hatching of the larvae. But some stars turn out to be caring parents: they wear caviar on their backs, and then larvae. For certain species of sea stars, for this purpose, during the mating on the back, there are special bags for caviar, which are well washed with water. There, she can stay with the parent until the appearance of the larvae.

Multiplication by division

Absolutely extraordinary ability of sea stars - reproduction by way of division. The ability to grow a new hand-ray exists for almost all animals of this species. A star caught by a predator by a ray can throw it away like a lizard's tail. And after a while grow new.

Moreover, if a small particle of the central part remains on the ray, a full starfish will grow out of it after a certain time. Therefore, it is impossible to destroy these predators, cutting them into pieces.

Who are afraid of starfish

The representatives of this class have few enemies. Nobody wants to get involved with the poisonous needles of the sea gods. Animals still know how to extract odoriferous substances to deter particularly greedy predators. In case of danger, the star can be buried in mud or sand, becoming almost invisible.

Among those who eat starfishes in nature, marine large birds predominate. On the shores of warm seas, they become prey for seagulls. In the Pacific Ocean cheerful otters do not mind staring.

Predators damage the underwater plantations of oysters and scallops - to what the starfish feeds. Attempts to kill animals, cutting them into pieces, led to an increase in the population. Then they began to fight with them, bringing the stars ashore and boiling in boiling water. But there was nowhere to use these remains. There were attempts to make a fertilizer from animals, while repelling pests. But this method has not received wide distribution.