The Sea Star is a type of invertebrate that lives on the sea floor and moves at night.They can be a variety of colors, shapes and sizes, although all resemble a star. While some appear smooth, they all have spines covering their upper surface and a soft underside.
If you gently turn over a live sea star, you'll see its tube feet wiggling back at you.
No sea stars are found in freshwater envirments, but only in Marine Habitats. They tend to hang around Reef and Kelp Forest. They love tropical and tropical-temperate areas in the Pacific Ocean and Eastern Atlantic Ocean.
- Sea stars are not fish. They do not have gills, scales, or fins like fish do and they move quite differently from fish. While fish propel themselves with their tails, sea stars have tiny tube feet to help them move along.
- Sea stars use sea water to pump blood and nutrients around their body.
- There are thousand of sea star species. There are about 2,000 species of sea stars. Some live in the intertidal zone, some in deep water, some in tropical areas, some in cold water.
- Not all sea stars have 5 arms. Some have many more. Take the sun star for instance, which has up to 40 arms!
- Sea stars can regenerate a lost arm. Sea stars house most of their vital organs in their arms, so some can even regenerate an entirely new sea star from just one arm and a portion of the star's central disc. It won't happen too quickly, though. It takes about a year for an arm to grow back.
- Sea stars are protected by armour. Sea stars have a tough covering on their upper side, which is made up of plates of calcium carbonate with tiny spines on their surface. A sea star's spines are used for protection from predators, which include birds, fish and sea otters.
- Sea star do not have blood. Instead of blood, sea stars have a water vascular system, in which the sea star pumps sea water through its sieve plate, or madreporite, into its tube feet to extend them. Muscles within the tube feet retract them.
|Marine||Marine Habitats • Aquariums • Global Oceans • Ocean Weather
|Vertebrate||Fishes • Mammals • Reptiles • Amphibians • Cartilaginous Fishes • Sharks
|Invertebrate||Arthropod • Mollusca • Echinoderms • Cnidaria
|Conservation Status||Critically Endangered • Endangered • Near Threatened • Vulnerable • Least Concern • Data Deficient • Not Evaluated|