IOO A NATURAL HISTORY OF THE SEAS 



fully sculptured. The various species abound on coral 

 reefs. 



The Scallops (Pectens) are nearly related and where 

 found are prized for their decorative and edible qualities. 

 Whereas large specimens are usually sedentary, the smaller 

 kinds are very active, floating through the water in boomer- 

 ang-like curves by rapidly opening and shutting their 

 valves. The animals are very readily aware of their 

 arch-enemy the Starfish, apparently sensing approaching 

 danger by sight, for the fringe of the animal's outer body 

 wall, or mantle, bears a row of eyes which show a sur- 

 prisingly high degree of development. 



The Eulamellibranchia include what perhaps is the most 

 important of all shellfish, the Edible Oyster. The Common 

 Oyster (Ostrea edulis) has played a part in popular literature, 

 and one can only regret the vanished days of Dickens's 

 time when the prince of shellfish was purchasable at 3d. 

 a dozen. Oysters are hatched from minute eggs, and 

 discharged in the form of spat as free-swimming larvae 

 which make their way to the sea surface and there live till 

 their shells are fully formed. They then sink to the sea- 

 bed and become attached to some stable object by the lower 

 or deeper shell. The providing of suitable anchorage, 

 technically known as " culching," is an important part 

 of oyster farming. Although a single oyster may discharge 

 itself of several million young a very small percentage 

 survive the carnage of the surface water, and even when 

 settled for life upon the sea-bed the animal is beset by 

 hosts of enemies. Whelks and the Boring Sponge tunnel 

 its shell, the Slipper Limpet smothers it, crabs heap silt upon 

 it, whilst Starfish, Octopuses or Wolf Fish devour it 



