Before we talk about sea stars, I want to answer a few questions sent to me about anemones. Claira S. asked “Can anemones sting humans?” Yes, however there are very few anemones (and none in the Puget Sound) that have a painful sting. Instead, the stickiness you feel is the anemones stinging you our relatively thick skin protects us from the extremely weak “stings.” Audrey S. asked “Do all anemones have stinging cells?” As far I I know all anemones have stinging cells because this is how they catch their food. The amount and strength vary by species.

Now for our next Marine animal post: Sea Stars!

Wait…Sea Stars? I though these were Starfish…

You can call them either name. I personally prefer using the name Sea Star because they are not fish, they are a type of invertebrate called and Echinoderm. (With this reasoning, I should also say Sea Jellies instead of Jellyfish but I have not been able to make that switch yet…)

The group of animals called Echinoderms include sea stars, sea urchins, sea cucumbers, and sand dollars. The name echinoderm means “spiny skin.” All animals in this group have some form of sines on the outside of their body. Other things these animals have in common is that they all use “tube feet” in order to move and have pentamerous radial symmetry, they can be “cut” evenly in five different ways.

The “spines” on sea stars are generally very small. For the sea stars pictured above are the white dots. These spines help protect sea stars from predators such as birds, fish crabs and otters.

They move around the sea floor using what are called tube feet. On the bottom of sea stars are hundreds of suction cups that are powered by the water that the sea star brings into its body. Not only do they use these tube feet to move, sea stars also use them to open clams and mussels. They grab onto the outsides of the clam or mussel shell and pull until the clam/mussel becomes too tired to hold their shells together. This is when the sea star takes its stomach out of it’s mouth to digest the inside of the clam/mussel.

Sea Star don’t just dine on mussels and clams. They also eat barnacles snails, sand dollars and sea urchins. Some sea stars even eat other species of sea star! They are important predators the sea floor, helping control populations of the animals they eat.

Lastly, sea stars also have incredible regenerative properties. As long as they still have most of the center of their body, they can regrow the rest of their body! Some times sea stars accidentally grow an extra arm in this process.

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