Echinoderms can, according to their body characteristics, be divided into five classes.
Main features: They have 5 arms that start in a disc located in the center of the animal's body.
Main features: have a round or flat body shape. They have 5 strong teeth in the mouth, which they use in the feeding process (mainly to eat seaweed).
Examples: sea urchin and beach cracker
Main features: have five arms, but these are separate from the central disc. Absence of anus.
Example: sea serpent (serpent stars).
Main features: The anus of these echinoderms is dislocated to the oral region. They live fixed to the marine substrate by the aboral region.
Example: Sea Lilies
Main features: They perform gas exchange through a structure called the respiratory tree. The spines of the body are small in size and the body is elongated in shape.
Example: sea cucumber