Is It Sea Star? Or Starfish? Or ‘Asteriod’?


By Angelica Romero Blancas
March 14, 2015, 8:57 a.m.

What lies in the ocean can be as much of a mystery as what exists in outer space. As we look yonder into the heavens we see the stars shining gloriously. On this planet, we have creatures that take their name after these heavenly bodies; we call their class “asteroidea” meaning “star like.” Commonly known as sea stars or starfish these creatures are an amazing testament of the resilience of sea water animals and an overall example of the different life forms and lifestyles that exist underwater.

Sea stars are an exotic natural beauty, often possessing five arms, but the number varies with some species have as many as 40. They come in various sizes and striking colors sometimes their bodies are adorned with protective spikes like punk children putting on a tough exterior to protect themselves and survive in the harsh and relentless environment that is the ocean.

As they are not actually fish, the technically-correct term for these animals are sea stars. They have no brains or blood. Instead of blood, sea stars filter ocean water through their bodies. Sea stars function without a brain by using a highly-developed nervous system with most of their vital organs tucked within their arms. They use their limbs and the tiny sensors protruding from them to feel their way and move across the ocean.

While sea stars do have an eye at the end of each “arm” scientists are still researching how effective these eyes are and what function they actually serve. Recent research indicates these ‘eyes’ are used to locate reefs where they can safely find food.

Regeneration is one of the most famous abilities that sea stars possess. They can loose a limb if attacked, leaving it behind for their predator, slowly fleeing before growing the limb back. Many lizards also use regeneration, losing inches off their tail when attacked, only to grow it back later. Most sea stars require their central body to be whole in order to regenerate; however, a few species in fact have the ability to regenerate themselves from part of a limb.

The sea stars’ limbs also prove to be pivotal for feeding. Despite having little to no eyesight, slow speed, and no brain, sea stars are carnivorous hunters, feeding primarily on mollusks, clams, oysters, sand dollars and mussels. They prey predominantly immobile species, rendering their own slow movement unimportant. Opportunistic hunters, sea stars will eat other creatures and organic material as long as it is an “easy catch.” They will consume snails and injured fish when available as well as sponges, plankton, or coral. Sea stars use their arms to pry apart shellfish to get at the prey’s muscle. Once opened, the sea stars stomach comes out of its body to swallow they prey, pulling it into their body to digest it internally.

Sea stars can live to approximatley 35 years old. They typically breed in the spring and can lay as many as 2.5 million eggs. Pregnant sea stars will feel “plump and spongy” with arms filled with eggs. Sea stars can have distinct genders and mate with each other, they may also change their sex or reproduce asexually. It is generally difficult to see the gender of a sea star and may require close inspection under the microscope to fully find out.

Time-lapse video of sea star feeding on side of aquarium. The pale white substance is its protruding stomach. YouTube.
Time-lapse video of sea star feeding on side of aquarium. The pale white substance is its protruding stomach. YouTube.

“Asterodea.” Oxford Dictionaries. Oxford University Press. 2015. Web. 09 March 2015.

Lee, Jane J. “Surprise! Scientists Find That Starfish Eyes Actually See, at Least a Little.” National Geographic. National Geographic Society. 1996-2013. Web. 09 March 2015. reef-ocean-animal-science/

“What do starfish eat?” What do they eat project. Web. 09 march 2015. “Starfish (sea stars)”/Animals. National Geographic. National Geographic Society. 1996- 2015. Web. 09 March 2015.

“Sea star.” Adapted from The Uncommon Guide to Common Life on Narragansett Bay. Save The Bay, 1998. Web. 09 March 2015. Coleman, Quentin. “Do Starfish Have a Gender?” Animals. Demand Media. 2015.Web. 09 March 2015.



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