Starfish and relatives

These amazing creatures are collectively known as Echinoderms (literally meaning – spiny skin). They all have five-fold symmetry, meaning they have five arms or segments in multiple of five. All have hard external armour known as an exoskeleton, and are slow moving creatures that generally live on the seabed.

Cotton Spinner - Holothuria forskali

This is a member of the sea cucumber family which are related to starfish. It is found in the deeper parts of the kelp forests and on sandy seabeds. This cucumber-shaped, and sized, animal is most often encountered around the south of the island. The cotton spinner has a mouth at the ‘head end’ with a very long gut finishing at the anus on the other end. The gut has to be very long and convoluted as the sea cucumber feeds on microscopic food found in the sand and on the seabed. This diet is very poor in nutrients so the long gut enables the most food to be digested. The name cotton spinner comes from the defence used against predators. The sea cucumber is able to spit out part of its very sticky gut which binds up the attacker allowing the cucumber to safely crawl away! After a while it is able to re-grow its lost gut and then continue feeding on the seabed.

 

Edible Urchin - Echinus esculentus

Sea urchins are members of the starfish family. They are found down to depths of 20m Below Sea Level (BSL), usually in kelp forests and on boulders. They are herbivores, plant eaters, feeding on the kelp plants and seaweeds found in the kelp forests. The central mouth (found in the middle of the underside) is shaped like a horny beak, consisting of five teeth, and is used to scrape away at plants. This amazing beak is called ‘Aristotles lantern’ as it was first described in great detail by the famous Greek philosopher Aristotle. The Latin name for the common urchin, Echinus actually means hedgehog and is a very good description of the almost spherical, spiky animal. Urchins are able to move around using tiny specialised tubes running vertically up and down the whole of the body. They are arranged in five paired rows, showing their relationship to the five-armed starfish. These tube-feet enable the urchin to move, slowly but surely, in almost any direction they wish. The suckers on the end of the tube feet mean that urchins can attach very securely to the rocky seabed. This is important when feeding in the kelp forests which are more exposed to waves and storms, like those found mostly in the north and west sides of the island, where a lot of urchins are found at Lundy.

 

Sunstar - Crossaster papposus

Closely related to starfish this animal is very distinctive and is found on hard seabeds at depths below 10 metres. The bold colouring and number of arms (ranging from 8-16) make this starfish appear just like a sun. They are very active predators, hunting other starfish and seashells. They can grow up to 35 cm across. All starfish, sunstars and brittlestars are able to slowly re-generate (replace) any arms that may be lost!