The echinoderms, to which the starfish belong, are representatives of a very special group. They are not like anyone. These marine inhabitants raise many questions, among which the following are of particular interest: "What does a starfish eat?", "For whom does it pose a mortal threat?"
Stars on the seabed
These unusual decorations of the seabed have existed on the planet for a long time. They appeared about 450 million years ago. Allocate up to 1600 types of stars. These animals inhabit almost all the seas and oceans of the earth whose water is quite salty. Stars do not tolerate desalinated water; they cannot be found in the Azov and Caspian seas.
Rays in animals can be from 4 to 50, sizes range from a few centimeters to a meter. The life span is about 20 years.
Marine inhabitants have no brain, but each ray has an eye. The organs of vision resemble insects or crustaceans; they distinguish light and shadow well. Many eyes help animals to hunt successfully.
Stars breathe almost through the skin, so it is very important for them to have enough oxygen in the water. Although some species can live in decent depths of the ocean.
Structural features
It is interesting how they reproduce, how starfishes feed. Biology classifies them as echinoderms. A starfish has no blood per se. Instead, the star’s heart pumps sea water enriched with certain trace elements through the vessels. Pumping water not only saturates the animal’s cells, but also, by pumping liquid in one or another place, helps the star to move.
Starfish have a ray diagram of the structure of the skeleton - rays radiate from the central part. The skeleton of sea beauties is unusual. It consists of calcite and develops inside a small asterisk from practically several calcareous cells. What and how starfish eat depends largely on the features of their structure.
These echinoderms have on their tentacles special pedicellaria in the form of tweezers at each tip of the outgrowth. With their help, the stars hunt and clean their skins from litter clogged between the needles.
Tricky Hunters
Many are interested in how starfish eat. Briefly about the structure of their digestive system can be found below. These amazing beauties give the impression of perfect security. In fact, they are marine predators, gluttonous and insatiable. Their only drawback is slow-moving. Therefore, they prefer a motionless treat - shells of mollusks. With pleasure, a starfish eats scallop, is not averse to eating a sea urchin, sea cucumber, and even inadvertently swimming a fish too close.
The fact is that the starfish has almost two stomachs, one of which can turn out. A careless victim, captured by the pedicellaria, is transmitted to the mouth opening in the center of the rays, then a stomach is thrown over it like a butterfly net. After this, the hunter can release the prey and slowly digest it. For some time, the fish even drags its executioner along, but the victim can no longer escape. All that the starfish eats is easily digested in her stomach.
It does somewhat differently with shells: it slowly approaches the dish that it likes, braids its shell around its shell, places a mouth hole opposite the shell slit and starts to open the wings.
Once a small gap appears, an external stomach is immediately pushed into it. Now the sea gourmet calmly digests the owner of the shell, turning the mollusk into a jelly-like substance. Such a fate awaits any eaten prey, no matter whether the starfish eats scallop or small fish.
Features of the structure of the digestive system
The predator does not have any devices for capturing prey. A mouth surrounded by a ring lip connects to the stomach. This organ occupies the entire inside of the disc and is highly flexible. A 0.1 mm gap is enough to penetrate the shell flaps. In the center of the aboral side, a narrow small intestine opens from the stomach. What a starfish eats depends on the unusual structure of the digestive system.
Love of the stars at the bottom of the ocean
Most starfish are heterosexual. At 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 tricks in advance seek to postpone nutrients for the entire time of mating.
The sex glands are at the stars near the base of the rays. When mating, females and males connect the rays, as if merging in a gentle embrace. Most often, caviar and male germ cells enter the sea water, where fertilization occurs.
In the case of lack of certain individuals, stars can change sex to maintain a population in a certain territory.
The caviar of these sea inhabitants most often remains on its own until the larvae hatch. But some stars turn out to be caring parents: they carry caviar on their backs, and then larvae. For certain types of starfish, for this purpose, during mating, special bags for caviar appear on the back, well washed with water. There it can be with the parent until the larvae appear.
Division propagation
A completely unusual ability of starfish is reproduction by the method of division. The ability to grow a new ray-arm exists for almost all animals of this species. A star caught by a predator by a ray can throw it away like a lizard tail. And after a while to grow a new one.
Moreover, if a small particle of the central part remains on the beam, after a certain time a full-fledged starfish will grow out of it. Therefore, to destroy these predators, chopping into pieces, is impossible.
Who are the sea stars afraid of?
Representatives of this class have few enemies. Nobody wants to mess with the poisonous needles of sea celestials. Animals can also emit odorous substances to scare away especially voracious predators. In case of danger, the star can burrow in silt or sand, becoming almost invisible.
Among those who feed on starfish in nature, marine large birds predominate. On the shores of warm seas, they become prey for gulls. In the Pacific Ocean, the star is not averse to relish funny sea otters.
Predators harm the underwater plantations of oysters and scallops - what the starfish eats. Attempts to kill animals, chopping them into pieces, led to an increase in population. Then they began to fight with them, bringing the stars to the shore and boiling in boiling water. But there was nowhere to use these remains. There have been attempts to make fertilizer from animals, which simultaneously repels pests. But this method was not widely used.