Echinoderms, which include the starfish, are representatives of a very special group. They don't look 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 seafloor
These extraordinary decorations of the seabed have existed on the planet for a long time. They appeared about 450 million years ago. There are up to 1600 types of stars. These animals inhabit almost all the seas and oceans of the earth, the water of which is quite s alty. 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.
Women of the sea don't have a brain, but every ray has an eye. The organs of vision resemble insects or crustaceans, distinguish wellLight and shadow. Many eyes help animals to hunt successfully.
The stars breathe almost through their skin, so it is very important for them to have enough oxygen in the water. Although some species can live at decent depths of the ocean.
Building features
It's interesting how they breed, how starfish feed. Biology classifies them as invertebrate echinoderms. The starfish has no blood as such. Instead, the heart of the star pumps sea water enriched with some microelements through the vessels. Pumping water not only saturates the cells of the animal, but also, by pumping fluid in one place or another, helps the star move.
Sea stars have a ray skeletal structure - rays extend from the central part. The skeleton of sea beauties is unusual. It is composed of calcite and develops inside a small star from almost a few calcareous cells. What and how starfish eat depends largely on the characteristics 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.
Cunning 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, voracious and insatiable. Their only drawback is their slowness. Therefore, they prefer a motionless delicacy - mollusk shells. With pleasure, a starfish eats a scallop, is not averse to eating a sea urchin, a trepang, and even a fish that has inadvertently swam too close.
The fact is that the starfish has almost two stomachs, one of which can turn outward. A careless victim, seized by pedicellaria, is transferred to the mouth opening in the center of the rays, then the stomach is thrown over it like a net. After that, the hunter can release the prey and slowly digest it. For some time, the fish even drags its executioner along with it, but the victim can no longer escape. Everything a starfish eats is easily digested in its stomach.
She does things with shells a little differently: she slowly approaches the dish she likes, braids the shell with her rays, places the mouth opening opposite the slit of the shell and begins to push the valves apart.
As soon as a small gap appears, the external stomach immediately pushes 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 victim eaten, whether the starfish feeds on scallops or small fish.
Features of the structure of the digestive system
The predator does not have any devices for capturing prey. Mouth surrounded by an annular lipconnects to the stomach. This organ occupies the entire interior of the disc and is highly flexible. A gap of 0.1 mm is enough to penetrate the shell flaps. In the center of the aboral side, a narrow short intestine opens from the stomach. What the starfish eats largely 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 sly ones tend to deposit nutrients for the entire time of mating in advance.
The gonads are located near the stars near the base of the rays. When mating, the female and male individuals connect the rays, as if merging in a gentle embrace. Most often, eggs and male germ cells end up in sea water, where fertilization occurs.
In case of a shortage of certain individuals, the stars can change sex to maintain the population in a certain area.
The eggs of these inhabitants of the sea most often remain on their own until the larvae hatch. But some stars turn out to be caring parents: they carry eggs on their backs, and then larvae. In certain types of starfish, for this, during mating, special bags for caviar appear on their backs, which are well washed with water. There she can stay with the parent until the larvae appear.
Reproduction by division
Absolutely unusual ability of starfish - reproduction by division. Skillto grow a new hand-beam exists in almost all animals of this species. A star caught by a predator by the beam can throw it away like a lizard's tail. And after a while grow a new one.
Moreover, if a small particle of the central part remains on the beam, a full-fledged starfish will grow out of it after a certain time. Therefore, it is impossible to destroy these predators by cutting them into pieces.
Who are starfish afraid of
This class has few enemies. No one wants to mess with the poisonous needles of sea celestials. Animals still know how to secrete odorous substances to scare off especially voracious predators. In case of danger, the star can burrow into the silt or sand, becoming almost invisible.
Among those who feed on starfish in nature, large sea birds predominate. On the shores of warm seas, they become prey for gulls. In the Pacific Ocean, cheerful sea otters are not averse to feasting on stars.
Predators damage underwater plantations of oysters and scallops - what starfish feed on. Attempts to kill animals by cutting them apart have led to an increase in the population. Then they began to fight with them, bringing the stars to the shore and boiling them in boiling water. But there was nowhere to use these remains. There have been attempts to make fertilizer from animals that repels pests at the same time. But this method was not widely used either.
