Starfish can live an average of 35 years in the wild. Their regenerative abilities contribute to their long lifespan. Vital organs are located in the arms, allowing a starfish to survive even if most of the body is destroyed.
Besides their regenerative abilities and unique shape, starfish also have a distinctive way of consuming their prey. They are able to expel the stomach through the mouth, slipping it inside shells to digest food before contracting it back into the body. Starfish refrain from becoming food themselves by having hard, calcified skin and the ability to blend with their environment. They are able to move away from light by sensing it with the small eye spot on the end of each arm.
Although starfish do not contain blood, they have a vascular system. Filtered seawater flows through the vascular system, allowing the arms of the starfish to extend for movement. Tiny tubes on their feet expand and contract to help them move.
Of the approximately 2,000 species of starfish, only some have five arms, with one species having up to 40. Also known as sea stars, starfish lack the gills and scales of fish and are actually echinoderms, closely related to sea urchins and sand dollars. They are marine animals found only in the ocean and brackish water.