Sea stars are actually part of the phylum Echinoderm and are related to sea urchins, brittle stars and sea cucumbers – they are not fish at all! Fish are vertebrates; sea stars are invertebrates. Fish are typically covered with scales; sea stars are typically covered with spines.
Sea stars, like sea urchins and sand dollars, do not have backbones, which makes them part of a group called invertebrates. Fish have backbones, which makes them vertebrates.
class AsteroideaStarfish belong to the class Asteroidea, derived from the Greek words “aster” (a star) and “eidos“ (form, likeness, appearance). There are more than 1600 species of starfish alive today, and they have an important role in the community structure of the ocean floor.
EchinodermStarfish / PhylumAn echinoderm is any member of the phylum Echinodermata radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies or "stone lilies". Adult echinoderms are found on the sea bed at every ocean depth, from the intertidal zone to the abyssal zone. Wikipedia
Starfish aren't actually fish For a start, they don't have gills, scales or fins like fish do, and they don't have a backbone, which means they belong to a group of species called invertebrates, along with urchins and sponges.
Echinoderms and other vertebrates are similar in the sense that they are all deuterostomes, meaning their anus emerged from blastopore. This piece of information suggests that they are cousins in evolutionary sense.
Sea stars, commonly called, "starfish," are not fish. They do not have gills, scales, or fins. Sea stars live only in saltwater. Sea water, instead of blood, is actually used to pump nutrients through their bodies via a 'water vascular system. '
They have a surprisingly unusual anatomy, with no brain or blood, yet are able to digest food outside their body.Starfish can regenerate their own arms. ... They have no brain or blood! ... They wear tough, leathery skin. ... Starfish have eyes. ... Starfish move with hundreds of feet. ... Starfish can eat outside their body.More items...
endoskeletonAlthough starfish are invertebrates, they do have a kind of skeleton. The bodies of starfish are composed of calcium carbonate plates, known as 'ossicles'. These form the endoskeleton, which takes on a variety of forms such as spines and granules.
How to Identify StarfishSize. Measuring the diameter, or total length across, of a sea star can be helpful in determining its species. ... Arms. While the most common number of arms on a starfish is five, certain species can have six, 10 or even more arms. ... Skin Texture. ... Color and Pattern.
Starfish are marine invertebrates.