Starfish are mainly distributed in shallow sand or rocks all over the world, which is no stranger to us. However, we know little about its ecology. Starfish doesn't look like an animal, and from its appearance and slow movement, it is hard to imagine that starfish is actually a greedy carnivore, which plays an unusually important role in marine biological system and biological evolution. This is why it is widely distributed in the world.
It is generally believed that sharks are fierce carnivores in the ocean. Who would have thought that the starfish, which lives on the sand or rocks at the bottom of the sea, is also a carnivore! But that's the truth. Because starfish can't move as flexibly and quickly as sharks, its main prey are some slow-moving marine animals, such as shellfish, sea urchins, crabs and anemones. It often adopts a slow and tortuous strategy, slowly approaching the prey, grasping the prey with the tube foot on the wrist and wrapping it all over, spitting out the stomach bag from the mouth, dissolving the prey in vitro with digestive enzymes and being absorbed by it.
We know that starfish is an indispensable link in the marine food chain. Its predation plays an important role in maintaining the balance of biota. For example, on the west coast of the United States, there is a spiny starfish, which often preys on sea rainbow (vegetables) densely covered on rocks. This can prevent the sea rainbow from over-breeding, prevent the sea rainbow from invading the territory of other creatures, and thus maintain the balance of biota. There are about 2000 species of starfish in the world, which are distributed in a vast territory from the ocean to the seabed. Among them, the northeast Pacific Ocean from Alaska to California has the most species.
Starfish, sea cucumbers and sea urchins belong to echinoderms. They usually have five wrists, but there are also four or six, and some have as many as 40 wrists. There are four rows of pins under these wrists. Using pins can not only catch prey, but also let yourself climb on rocks. Sea star has thousands of tube feet. Starfish's mouth is in the middle of its lower body, which can directly contact the surface of the object that starfish has climbed. Starfish vary in size, ranging from 2.5 cm to 90 cm, and their body colors are different. Almost every one is different. The most common colors are orange, red, purple, yellow and cyan.
In the natural food chain, the contest between predator and prey is often life and death. In order to escape from starfish, almost all prey animals will make an escape response. There is a big sea cucumber. Whenever the starfish touches it, it will roll violently in the water and run away before it is firmly caught by the starfish. Scallops also have unique skills in avoiding starfish. When the starfish approaches it, scallops will swim quickly one after another. There is a little anemone. Whenever the starfish approaches it, it will break away from the climbing rock and drift to a safe place. The ability of these animals to escape comes from long-term evolution. Avoid the fate of being eliminated by nature.
Although starfish are fierce predators, they are gentle to their offspring. Starfish often erect their wrists to form an umbrella after laying eggs, so that the eggs can hatch in it to avoid being preyed by other animals. The hatched larvae drift with the sea water and feed on plankton, and finally grow into starfish.
Starfish has little economic value, so it can only be dried and ground into powder for agricultural fertilizer. Because it preys on shellfish, it is very harmful to shellfish culture.