According to other observers the starfish seizes the oyster with two of his fingers, while with the other three he files away the edge of the flat or upper valve until the points of contact with the round valve are reduced almost to nothing; then he can introduce an arm, and the rest is easy work. Others suggest that the starfish suffocates the oyster by applying two of its fingers so closely to the edge of the valves that the oyster is unable to open them; after a while the vital powers relax and the shell gapes. The Rev. J. G. Wood holds[225] that the starfish pours a secretion from its mouth which “paralyses the hinge muscle and causes the shell to open.” Sometimes in a single night a whole bed of oysters will be totally destroyed by an invasion of starfish. Another dreaded enemy is the ‘whelk,’ a term which includes _Purpura lapillus_, _Murex erinaceus_, _Buccinum undatum_, and probably also _Nassa reticulata_. All these species perforate the shell with the end of their radula, and then suck out the contents through the neatly drilled hole. Skate fish are the cause of terrible destruction in the open beds, and a scarcely less dangerous visitant is the octopus. Crabs crush the young shells with their claws, and are said to gather in bands and scratch sand or mud over the larger specimens, which makes them open their shells. Yet another, and perhaps unconscious, foe is found in the common mussel, which takes up room meant for the young oysters, grows over the larger individuals, and harbours all sorts of refuse between and under its closely packed ranks. _Cliona_, a parasitic sponge, bores in between the layers of the oyster’s shell, pitting them with tiny holes (corresponding to its _oscula_), and disturbing the inmate, who has constantly to construct new layers of shell from the inside. Weed, annelids, ‘blubber,’ shifting sand or mud, sewage or any poisoning of the water, are seriously harmful to the oyster’s best interests. A very severe winter is often the cause of wholesale destruction in the beds. According to the _Daily News_ of 26th March 1891, the Whitstable oyster companies lost property to the value of £30,000 in the exceptionally cold winter of 1890–91, when, on the coast of Kent, the surface temperature of the sea sank below 32°, and the advancing tide pushed a small ice-floe before it. Two million oysters were laid down in one week of the following spring, to make up for the loss. During the severe winter of 1892–93 extraordinary efforts were made at Hayling I. to protect the oysters from the frost. Twenty million oysters were placed in ponds for the winter, and a steam-engine was for days employed to keep the ponds thawed and supplied with water, while large coal and coke fires were kept burning at the edge of the ponds.[226] On the other hand, the unusually warm and sunny summer of 1893 is said to have resulted in the finest fall of spat known in Whitstable for fifty years.[227]