Sea Star

A sea star, commonly known as a starfish, is a marine invertebrate belonging to the class Asteroidea. They are echinoderms, related to sea urchins and sand dollars, and are known for their radial symmetry, typically with five arms.

Sea stars have a central body disc with arms radiating from it, although some species can have more than five arms. Their body is covered in a hard, spiny, or bumpy exterior. The underside of each arm is lined with hundreds of tube feet which are used for locomotion and to grip prey. They have no brain and no blood; instead, they operate using a hydraulic system called the water vascular system.

Sea stars are found in all of the world's oceans, from the tropics to the cold polar waters. They live in a variety of marine habitats, including coral reefs, rocky shores, and sandy seabeds. They are opportunistic predators that feed on a variety of prey, including clams, oysters, and mussels. A sea star can extend its stomach out of its mouth to engulf and digest its prey.

One of the most remarkable abilities of a sea star is its power of regeneration. If a sea star loses an arm, it can grow a new one. In some cases, a single arm can even regenerate an entire new body, as long as a portion of the central disc is attached. This ability is a key survival mechanism against predators.