Last week, a jellyfish. This week, another invertebrate! Our fish of the week, the brittle sea star (not starfish, to be PC), is a member of the echinoderm phylum. This collection contains the other, fleshier sea stars, sand dollars, sea cucumbers and sea urchins. They all have spiny body parts, tube feet for locomotion and 5-part body symmetry. Tube feet act like tiny suction cups on the bottom of an echinoderm. They use water chambers within their body to control their suction (aka water vascular system). These feet can also be used to pry apart prey or pass food morsels to the centrally-located mouth. Sea stars actually evert their stomachs outside of their bodies in order to digest their prey!
There are over 1800 different species of brittle stars. They come in a variety of sizes and colors and are common in many ocean habitats. True to their name, brittle stars are very delicate, but thankfully, like other sea stars, they can regenerate their arms. Their slender nature allows them to wedge themselves into cracks and crevices for protection. They can live for 10-20 years if nothing comes along to eat them. Fishes, crabs, lobsters and even other sea stars snack on brittle stars. If they are attacked, a brittle star can drop off the attacked limb and make a getaway while the predator is distracted by its snack.
For more information on brittle stars and other invertebrates, check out A Snail’s Odyssey. This website focuses on marine invertebrate research involving west coast species.
