CH. Ill] LIFE IN THE SEA 65 



through the Baltic or North Sea or both, or through the English 

 Channel in order to reach their spawning ground in the North 

 Atlantic south-west of the Faeroe Islands, while the comparatively 

 feeble larva or Leptocephalus makes a correspondingly long 

 journey to reach the rivers into which it ascends to pass through 

 its adolescent phase. The migrations of the sturgeons occasionally 

 caught in the English Channel or in the Irish Sea may be com- 

 pared with those of the migratory birds. Some invertebrates are 

 also nektic animals, as for instance the lobsters, crabs, and some 

 other Crustacea, which are powerful and intelligent animals and 

 move about as they please. Cuttlefishes and squids certainly do 

 so. Some worms may belong temporarily at least to the nekton, 

 and the large medusae, though perhaps better classed with the 

 plankton, do move about " of their own accord." Like the benthos 

 of the moderatel}^ shallow seas the nekton varies of course with the 

 locality. 



The plankton. When we have considered the organisms of 

 the benthos and nekton we have apparently exhausted the visible 

 life of the sea. But by far the greatest proportion of this 

 must belong to the plankton. The mariner, it has been said, 

 when he sails over a tract of sea thinks that he traverses a "barren 

 w^aste of waters" through which there swims here and there an 

 occasional fish or porpoise. But in reality he sails over a "pasture," 

 and beneath his ship is a wealth of life much more abundant than 

 is contained in the richest or most luxuriant forest. Beneath his 

 feet may be a couple of miles of water and every cupful of this 

 may teem with life, and this is so even if no fishes or other large 

 animals may be visible. This enormously abundant life is the 

 plankton, the drifting fauna and flora of the sea, the presence of 

 which is only revealed by the tow-net and microscope. Of all forms 

 of marine biological investigation the study of the plankton is the 

 most entertaining. Equipped with the tow-net and microscope the 

 naturalist finds here a veritable " wonderland " awaiting him, 

 and the variety and beauty of the creatures so obtained, and the 

 ever present possibilities of finding forms of life new to science, 

 combine to make the study of the plankton a most fascinating one. 

 To any one who lives near the sea the observation of the microscopic 



J. F. 5 



