Sea stars are invertebrates related to sea urchins, sea cucumbers and sand dollars, which are all echinoderms. Echinoderm means spiny skin—a reference to their hard, calcified skin, which helps to protect them from predators.
Sea stars have rows of tiny tube feet extending from the grooved surface on their underside. These tube feet allow them to crawl along the ocean floor using suction created by an internal water-driven hydraulic system.
These animals also have an amazing ability to regenerate arms when they are severed, or even a new body in some species. All of their vital organs are located in the arms, so a portion of an arm could potentially grow a whole new sea star. Most species have five arms, but some have many more—even as many as 40!
At the Aquarium, you can see 10 species of sea stars throughout the exhibits. Look closely in the kelp forest habitat to spot the sun sea stars, which have 20 arms each! Learn more about sea stars! Did you know that sea stars have a peculiar way of eating?
They digest prey outside of their bodies by extruding their stomach out through their mouth and enveloping their meal. The dorsal surface is rough with projecting spines. The ventral surface is flat, with the mouth at the centre. Each of the mouth's plates bear two spines. Its colour varies but is most commonly pale orange, brown, green or cream. Distribution Common on all British coasts but sparse in the North-East and not recorded from Lincolnshire around to Hampshire.
Habitats Coastal Marine. Did you know? All Cushion stars are born male! It is a "protandrous hermaphrodite", meaning that small or young individuals are males but when individuals increase beyond a certain size, they develop into females. How people can help When rockpooling, be careful to leave everything as you found it - replace any seaweed you move out of the way, put back any crabs or fish and ensure not to scrape anything off its rocky home.
If you want to learn more about our rockpool life, Wildlife Trusts around the UK run rockpool safaris and offer Shoresearch training - teaching you to survey your local rocky shore. Jump to navigation. The cushion star is a sea star that gets its common name from its inflated, pillow-like appearance. This species lives on coral reefs throughout the Indo-Pacific, and its species name Culcita novaeguineae reflects its discovery and commonness in New Guinea.
Juveniles look like typical sea stars, but as the cushion star grows, it becomes more inflated and the arms grow together, eventually reaching a point where they are almost no longer discernible. On the underside, however, the cushion star clearly shows its five-part symmetry, particularly near the mouth.
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