The different species of starfish make up the same group of invertebrate animals. In the classification of species or taxonomy these animals are part of the asteroid class.
Organisms that remind us of the stars in the sky
The asteroid name has a logical explanation , since the appearance of these invertebrates is very similar to that of some stars in the sky. In this sense, it should be noted that the word asteroid was first used by the English astronomer William Herschel to designate celestial bodies that have a resemblance to stars but are not really.
Fascinating organisms
From the point of view of species classification, starfish are not fish but echinoderms (the sea urchin and the starfish are also part of this classification).
These organisms lack brains and blood. Although most have five arms, some species can have as many as fifty (for example, the Antarctic starfish). Both his arms and his body can be fully regenerated.
Its arms are born from the central disk of its body and under this structure is the mouth of the star.
These echinoderms have a calcified skin that serves as protection against the threat of predators. Likewise, the skin has bright colors in order to scare off potential attackers.
Their body structure has different textures, as some species are smooth and others are spiny or grainy. In any case, all of them are covered by overlapping bone plates.
Their nervous system is not centralized, so they are able to perceive their surroundings from any part of their body (the sensory cells of their skin allow them to perceive light or the action of marine currents).
Most species are 12 to 24 cm in diameter . There are exceptions to this general pattern, as some species are a few millimeters long and others are over a meter long.
Regarding their distribution, they are present in all the oceans of the planet, both in cold and tropical waters, in coastal areas or thousands of meters from the surface. However, they do not exist in fresh waters.
The radial symmetry of these invertebrate animals is one of their most unique characteristics (the symmetry of the starfish is similar to that of sea urchins in their skeleton).
Regarding their diet , they eat a carnivorous diet of small invertebrate organisms, such as clams and oysters. To feed on prey, it places its feet on them and later secretes an anesthetic substance that paralyzes its prey.
These marine invertebrates are most active at night. Its movements are possible due to the action of its tube feet that incorporate suction cups adapted to the depths of the marine environment.