168 HALF AN HOUR WITH SEA-URCHINS 



would never imagine that the only means they 

 possessed of overcoming such difficulties was their 

 hundreds of thread-like suckers. Their mouth is in 

 the centre of the lower surface, but it has no teeth 

 like the sea-urchin. And yet it is surprising what 

 large-sized molluscs it manages to swallow, appearing 

 to dissolve the shells by its strong gastric juice. 

 The manner in which star-fish feed on oysters is 

 very peculiar ; they are the worst enemies of that 

 favourite dainty ; so much so that it is not long since 

 a law existed, enacting that no fisherman should 

 throw overboard a star-fish that had got entangled 

 in his net. Of course, these animals have not the 

 power of mechanically forcing open the solid shells 

 of oysters, although the ancients thought they had. 

 But they seem provided with some subtle poison 

 which they instil into the oyster, the result being 

 that the latter gets immediately benumbed, and 

 yields up the ghost. The ravages which star-fish 

 commit on oyster-banks are dreadful. But it has 

 been found that the cuttle-fish is quite as fond of the 

 star-fish, and by introducing them to their neigh- 

 bourhood oyster-growers might realise a practical 

 benefit. Many parts of the sea-bottom are literally 

 carpeted by these star-fish, so that we may expect 

 few chances for molluscs to survive under such 

 circumstances. The anus of the star-fish is situated 

 on the upper surface of the animal. 



We have referred to the stomach of this creature, 

 but should now add that this stomach is prolonged 



