Echinoderms

The British Echinoderms depicted in this chalk drawing  are two sea urchins, a cushion star or 'starlet', a common starfish, a brittlestar and a sea lily. In his book A Year at the Shore Gosse writes 'I am yet struck with admiration at the structure of a [sea urchin] when ever I examine it'.  Adult urchins have a fascinating and complex structure called 'Aristotle's lantern'.  This is used for chewing and is controlled by 60 muscles.