Unique Sea Creatures Gets New Name

by Patricia Cazares, age 12

Did you know that starfish are not actually fish? In fact, because of this, scientists are changing this well-known name to sea stars because these animals are more closely related to sand dollars, sea urchins, and other species of echinoderms.

Echinoderms are spiny marine invertebrates that have an internal calcified skeleton. Sea stars, which are a part of the echinoderm family, have many interesting adaptations that allow them to withstand a tough life at sea. To keep cool during low tide, sea stars suck up water into their bodies during high tide and store it. This cooling strategy allows sea stars to stay close to mussels, their preferred food source, which live near the shore.

Sea stars are 12 to 24 centimeters long and can weigh up to 11 pounds. They are invertebrates, meaning they do not have a backbone. They usually live for about 35 years. There are about 2,000 species of sea stars living in the world’s oceans. Very few sea stars live in brackish water, and there are no freshwater sea stars.

The most common sea star has only five arms, but certain species can have up to 40 arms. These creatures have bony skin, but do not have a brain or blood. Instead of blood, filtered seawater runs through their bodies. The rough quality of their skin protects them from predators, while their skin color acts as camouflage and defense.

Sea stars are famous for their ability to regenerate limbs. They can do this because most of their vital organs are located in their arms. In fact, some types of sea stars can grow into a brand new sea star from just part of a limb that has been cut off.   

The sea star also has the ability to eat dinner outside of its body. Its stomach oozes out of the sea star’s mouth, consumes and digests its prey and oozes back in, yet another interesting fact about these unique creatures.

[Source: Smithsonian; National Geographic]