Starfish, also known as sea stars, are not really fish despite their name and are actually echinoderms. There are 2000 species of starfish found in the world’s oceans and they have an important role in the community structure of the marine floor.
Starfish can sense light and various kinds of shapes with the help of an eye spot at the tip of each arm. They do not have blood or brains, but instead use filtered seawater to perform the function of blood. For movement purposes, starfish use their tube like feet that lie on the inner side of their body. These tubes help these creatures to crawl easily and quickly under the ocean surface.
Although starfish have no brain, they have two stomachs to help with the digestion of their food. The pyloric stomach allows for complete digestion while the cardiac stomach allows the starfish to digest food outside their bodies which means they can eat prey larger than them.
Starfish can change gender from male to female or female to male at any time. Female starfish make millions of eggs, which they release the eggs into ocean never going back to care for them.
The majority of echinoderms have 5 arms. Their body plan has five sections arranged around a central disk. Some have many more, the sun star can have up to 40 arms! Why? Starfish can regenerate limbs and sometimes entire bodies. If a starfish is caught by a predator they will sometimes drop their arms to escape then grow them back. They do this by housing most of their vital organs in their arms. As a result, they can live up to 35 years!
Can you imagine having the ability to regrow a part of your body?
Regeneration is one way starfish have remained abundant in the diverse marine world. Investigation into the regenerative mechanisms and processes in starfish can facilitate our understanding of how regeneration works to improve tissue regeneration in humans.