Echinoderms, which include the starfish, are representatives of a very special group.
They do not look like anyone. These sea creatures raise many questions, among which the following are of special interest: “What does a starfish eat?”, “For whom does it pose a deadly threat?”.
These extraordinary ornaments of the seafloor have existed on the planet for quite a long time. They are distinguished by up to 1600 species of stars. These animals inhabit almost all seas and oceans of the earth, whose water is quite salty.
Stars do not tolerate desalted water, they do not meet in the Azov and Caspian seas. The rays of animals can be from 4 to 50, sizes range from a few centimeters to one meter. The life span of animals is about 20 years. Sea women have no brain, but every ray has an eye. The organs of vision resemble insects or crustaceans; they can distinguish light and shadow well. A lot of eyes help animals to hunt successfully.
Stars breathe practically through their skin, so they need to have enough oxygen in the water. Although some species may live in decent depths of the ocean.
Features of the structure
It is interesting how the stars multiply and how they feed. Biology classifies them as echinoderms. A starfish has no blood per se. Instead, the heart of the star pumps seawater, enriched with some trace elements, through the vessels. The pumping of water not only saturates the cells of the animal but also by injecting fluid in one or another place helps the star to move.
Sea stars have a radiation pattern of the skeleton structure – the rays depart from the central part. The skeleton of sea beauties is unusual. It consists of calcite and develops inside a small star practically from a few lime cells. What and how sea stars eat depends largely on their structure.
These echinoderms have on their tentacles special pedicellariae in the form of tweezers at each tip of growth. With their help, stars hunt and clean their skins from the debris clogged between the needles.
Many people are interested in how the stars of the sea feed. Briefly about the structure of their digestive system can be found below. These amazing beauties create an impression of perfect safety. In fact, they are sea predators, voracious, and insatiable. The only drawback is their quietness. That is why they prefer the fixed dainty – shells of clams. With pleasure, a starfish eats a scallop, does not mind eating a sea urchin, trepang, and even a fish that has inadvertently swum too close.
The fact is that the starfish has almost two stomachs, one of which can turn outward. The careless victim, grabbed by pedicellariae, is transferred to the mouth hole in the center of the rays, and then, like a net, the stomach is thrown over it. After that, the hunter can release the prey and slowly digest it. For some time, the fish even drags its hangman, but the victim will not get out. All that the starfish eats is easily digested in its stomach.
It does a little differently with shells: slowly approaching a favorite dish, braiding the shell with its rays, placing the mouth opening against the sink gap, and begins to move the doors.
It is worth at least a small slit, in which the outer stomach is pushed immediately. Now the sea gourmand quietly digests the owner of the sink, turning the mollusk into a jelly-like substance. This fate awaits any eaten victim, whether the starfish eats a scallop or a small fish.
Features of the structure of the digestive system
The predator does not have any devices for capturing the prey. The mouth, surrounded by a ring lip, is connected to the stomach. This organ occupies the entire interior of the disc and has high flexibility. A slit of 0.1 mm is enough to penetrate the shell casings. In the center of the abdominal side opens the narrow short intestine, coming from the stomach. What the starfish eats depends largely on the unusual structure of the digestive system.
Most sea stars are of different sexes. During the love games, the individuals are so busy with each other that they stop hunting and have to fast. But it’s not fatal, because, in one of the stomachs, these tricks in advance tend to delay the nutrients for the whole mating time.
The sex glands are at the stars near the base of the rays. When mating female and male combine the rays as if merging in a gentle embrace. Most often, caviar and male sex cells get into seawater, where fertilization takes place.
In case of a shortage of certain individuals, the stars may change the sex to maintain the population in a certain area.
The caviar of these sea creatures most often remains on its own until the larvae hatch. But some stars turn out to be caring parents: they wear caviar on their backs, and then the larvae. Certain species of sea stars have special caviar bags on their backs during mating, which are well washed with water. There it can be with a parent until the larvae appear.
Reproduction by division
Absolutely extraordinary ability of sea stars is a reproduction by the method of division. The ability to grow a new ray arm exists in almost all animals of this species. A star grabbed by a predator by the beam can throw it away like a lizard’s tail. And after a while to grow a new one.
Moreover, if a small particle of the central part of the ray is preserved, after a certain time a full-fledged sea star will grow out of it. Therefore, it is impossible to destroy these predators, cutting into pieces.
Who are the starfishes afraid of?
Representatives of this class have few enemies. No one wants to get involved with the poisonous needles of sea celestials. Animals still know how to secrete odorous substances to scare away particularly voracious predators. In case of danger, a star can bury itself in mud or sand, becoming almost invisible.
Among those who feed on sea stars in nature, sea birds dominate. On the shores of warm seas, they become prey to seagulls. In the Pacific Ocean, a star is not averse to cheerful Sea otters.