Cushion Sea Stars
New zealand common cushion star Patiriella regularis Star fish? But they aren’t always star shaped? Are they EVEN fish? WHERE DO THE LIES END!!?? Why hello there curious one, if questions plague your mind about ocean critters as much as they do mine, then you’re in the right place. This is an introductory blog post for what will hopefully be a series where I discuss some cool underwater critters you might see whilst diving and snorkelling in New Zealand. Learning about these species means you can point them out to your friends and honestly, being in the ocean is so much more fun when you know about what's there with you (cue the JAWS theme music). Today's crucial topic: New Zealand's common cushion star (Patiriella regularis if you’re a fancy fish bish).
A Little Brush Up on Sea Stars.. Now, sea stars is actually more of an appropriate name since they aren't ACTUALLY fish. For those new to sea stars: They belong to a phylum (big group) called “Echinoderms” (EE-KINE-O-DERMS), which means “spiny skin”. Examples of echinoderms include sea stars, sea urchins, sea cucumbers, brittle stars and so on and so forth. Sea stars belong to the class (smaller group) “Asteroidea”, but enough about that. There are roughly 2,000 species out there, and they can be less than an inch to three feet in diameter, and some can live to about 35 years! They are a bit strange, they don't have a head, or blood, but instead pump water through their body. They do have eyes though, of sorts… Ocelli are at the end of their arms, and detect light. They use thousands of tube feet on their underside to walk, and have five or more arms.
Meet the Cushion Star The sea star Patiriella regularis, commonly known as the cushion star, is New Zealand's most common native sea star species. It is found in shallow waters on rocky shores of New Zealand. As seen by iNaturalist, they are found all around New Zealand's coasts (wow thats one dominant species!) This lil cushion of goodness is generally found in the lower tidal zone, and range in trophic level, but are mostly seen as herbivores. One cool fact is that sea stars' mouths are located central of their underside, and in order to feed, this sea star expels its stomachs over their food! Now I know what you're thinking, "uhm excuse me what are these spiny creatures from hell?"; Well yes it is creepy, but I think you're just jealous you can't do that too (Unless maybe you have dairy?). Once they have captured or surrounded their prey, e.g algae, barnacles and invertebrates, they can digest it. Another cool fact is that Sea stars don't use gills or lungs to breathe, but instead they rely on diffusion across surfaces in their body. Now, you have probably seen these sea stars before, they are pictured above, and tend to be all sorts of colours, but mostly blue/green/grey and a range of oranges.
Dive In and Explore! Remember to be brave and get out into the water. Grab a friend, meet someone new, and dive into the unknown. Always tell someone where you're going. The ocean's a big place, and you don't want to end up starring in your own lost-at-sea movie! The ocean is such a beautiful place that will love you back if you let it. I hope you encounter a cushion star soon and impress your friends with your newfound knowledge. Until next time, happy diving!
