Sea Stars
Main Information
A sea star is an echinoderm. They are famous for their ability to regenerate a whole new sea star or limb from a fallen arm! Their are no freshwater sea stars and do not produce blood. They have five sections and are related to sea urchins and sand dollars. The most common sea stars are the ones who have five arm or the five arm varieties. Some sea stars are able to consume their prey outside their bodies.
Size in Numbers
There are about 2000 species of sea stars living in the worlds oceans. Some live in brackish water. A large sea star called Acanthaster planci (also called the crown of thorns) can grow to diameters of more than a meter and can have up yo 21 arms. It is covered with long, sharp, venomous spines and can move up yo 20 miles per hour(mph)! Sea stars can be up to 12 inches when mature.
Diet
Sea stars are carnivores. They eat clams, barnacle, mollusks, oysters, coral, fish, and many other animals. They push out their stomach out through their mouth and digest their prey. Sea stars get eaten by sea gulls( at low tides), fish, sea otters, and crabs. Since sea stars have spines that are very sharp many sea animals avoid having them for food, but these sea animals listed above dont get to the spines.
Apperance
Sea stars have bony, and calcified skin. This protects them from most predators. Sea stars have striking colors that camoflouge them from their enemies. They also use their spines for protection. All sea stars have different colors, shapes, and sizes. They have five equal segments with each containing a set of internal organs. Sea stars have no heart, brain, or eyes. Their mouth is on the underside and the anus is on the top.
Mating
Sea stars breed in spring producing as many as 2,500,000eggs!!! Their method of mating is unique among all sea stars. The process of how the baby sea stars are born is first females let go of their eggs and the male lets go of the sperm. Then, the inside cells of the babies are begginning to divide every minute until the embryo hatches. After a while the larva begins to emerge, and so on.
Behavior
Sea stars use their suction on their tubed feet to move and feed in the water. They feed often, and their size depends on the amount of food they eat not on their age. Flexible bodies, and suckered tube feet keep sea stars firmly in place so they can withstand the forces of the crashing waves coming back and forth. They are not considered endangered or threatened sea animals!!