Is Starfish a Fish? All About the Starfish

Did you know that the word starfish refers to thousands of species of star-shaped marine animals? They live underwater; that’s why they have this resemblance to fish ends. It’s even more confusing sometimes, so you probably ask yourself “Is starfish a fish?”

Perhaps you’re one of those who like sea creatures like a starfish. That’s why in this blog, you will know important facts about starfish. You will also know if they truly are fish, as this is a common question that people would ask. So without further ado, let’s get started.

Is Starfish a Fish? 

So, is starfish a fish? Starfish is a common term that can be confusing. The truth is, starfish are not fish. They are not tailed or finned sea creatures that have backbones. Instead, starfish are echinoderms, also known as marine invertebrates.  They are noted as sea stars because of their shape that looks like a star.  This is the reason why scientists choose to call these sea creatures like sea stars. They are related to other echinoderms such as sea urchins, sand dollars, and sea cucumbers.

Sea stars also come in all shapes, sizes, and colors. They are known to have 5 point radial symmetry – however, it doesn’t mean that sea stars only have five arms. Many sea stars come with five arms, and these species only have a traditional star shape. There are also other species, like a sun star, that can have 40 arms shining out from their central disk.

They belong in the Class Asteroidea. It means that they don’t have blood. Instead, they have a water vascular system to draw seawater into their body through a madreporite. It moves through a series of canals, and the water gives structure to the starfish's body. The water is used to force the animal’s tube feet to move.  

And though sea stars don’t come with tails, gills, or scales as fish do, they still have eyes. Their eyes can be found on each of their arms, and it’s not that complex. However, there are eyespots that can sense if it’s dark or light. Then, of course, sea stars reproduce by releasing eggs and sperm into the water. They can even reproduce asexually through regeneration.

Interesting Facts About Starfish

Now that there is an answer to your question about “Is starfish a fish?”, then you must also know some of the interesting facts about starfish. Here are some of the notable facts about starfish you probably didn’t know about.

Sea Star Regeneration 

Did you know that starfish have the ability to regrow some parts of their body? They can regrow their damaged and lost arms. They use their arms as means of defense. And if an arm is damaged by the predator, like other crabs or starfish, they can just detach their arm and grow another healthy one.

Also, if their predator would grab onto them, sea stars can just detach their arm to escape. It’s good to know that starfish can regenerate, which would keep them abundant in the wild. So, is starfish a fish? Well, just think about how they have this kind of ability to regenerate that fish can’t.

Bony Skin 

Sea stars have calcified and bony skin that protects them from predators. They also have striking colors that will camouflage to scare off attackers. Their skin also varies depending on their species. Some species have leathery and prickly skin. In addition, they have a tough covering on their sides that is made of plates of calcium carbonate that come with small spines.

They Have 2 Stomachs

Sea stars are also known for having two stomachs. First, they have a cardiac stomach that eats their food outside their body. Then, when the cardiac stomach comes back into their body, the food will be transferred right away to the pyloric stomach. After which, the tube feet would open the shell of its prey, and the cardiac stomach would be extended to the shell to pull the food inside.

Sea Star Feeding 

Did you know that most of the starfish are predators? They feed on clams and mussels that are found on the ocean floor. Other species have particular feeding behaviors, which include eversion of the stomach.

This means sea stars extend their stomachs out of their mouth and their digestible parts. They also prey on tissue that they digest partially outside of their body. Then, finally, sea stars bring their stomachs back inside their digestive glands to finish eating.

Sea Star Movement 

Sea stars contain thousands of tube-like feet on their ventral sides that come with cells that are for adhesion. The sea stars can use the tube feet to move across the surface. Each foot also has two sets of cells that secrete compounds to allow the foot to attach and detach to the surface.

The set of cells will release an adhesive material that will bond the coat to the ocean floor surface. There is also another substance that is being released from the other type of secretory cells. It would enable the sea star’s foot to release from the ocean floor or any other surface.

Conclusion 

Starfish or Sea Stars, and other echinoderms are considered very important to the biodiversity of the ocean. So now that you find the answer to the common question, ``Is starfish a fish?” Hopefully, the next time you go to the beach and see starfish, you will take the opportunity to reflect and appreciate their beauty. They are as important as other sea creatures in the ocean.

They are not only important to the ocean, but their lives are also important on this planet. And if you love starfish and want to treasure them, you should check out our  ATOLEA Jewelry collection for more Starfish-designed jewelry. Instead of picking them up and harming them, you might as well consider getting a charm that you can wear every day. It’s way better than touching them, as it could get them at risk.

Check out more of our ATOLEA Ocean-inspired jewelry collections and join us in showing the world our deep passion and love for the Ocean!