Starfish are often overlooked as a marine organism. They are categorised as a common sight in rock pools and often pictured on the front of pocket shore ID guides where they slip into the norm not to be excited by. I personally hadn’t really given them much thought further than thinking
they look a bit strange (star shaped with no apparent eyes, mouth, general features) and knowing that they have the ability to grow their legs back.
After coming across a spiny starfish in a rock pool and being amazed both by its size and appearance (I’d only associated common starfish with UK shorelines) I decided to research more into these unassuming looking organisms.
Spiny starfish – Marthasterias glacialis – can be found on the west coast of the UK, Wales and Scotland and are a member of the echinoderm phylum which it shares with urchins and sea cucumbers.
They are star shaped and have eyes, mouth and general features!
– The star shape is a characteristic of radial symmetry exhibited by echinoderms.
-The eyes, more specifically ocelli, are on the ends of their legs and although basic can differentiate between light and dark.
-The mouth is based on the underside of the starfish and its anus on top. They are opportunistic feeders and feed by pushing their stomach over the prey digesting it and consuming the digested gloop.
-Features of interest include their spines used for protection, their range of colour greens/ browns/reds/greys/ beige with purple tips, their size as they can reach up to 70cm and ability to live at depths of 200m.
More generally but still interestingly like all starfish they use tube feet that adhere to the substrate and through coordination allow for movement as well as attachment to rocks. And their regeneration … they can regenerate a leg as long as some of the central disc is present – Starfish can regrow legs!! I think this above all is worth getting excited about!
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