120 STUDIES IN INSECT LIFE, ETC. 



and make up sometimes as much as 75 per cent, 

 of the total. He calculates that the plants on 

 an average make up 56 per cent, and the animals 

 44 per cent, of the total drifting organisms in 

 these regions really not a very large margin of 

 safety for animals. 



It should perhaps be mentioned that much of 

 this floating Plankton is, like the abysmal fauna, 

 highly phosphorescent and is indeed the phos- 

 phorescence with which we are all familiar. It 

 was surface phosphorescence that the .ever-obser- 

 vant Pepys noticed when he described the " strange 

 nature of the sea-water on a dark night that it 

 seemed like fire upon every stroke of the oar." 



Between the floating Plankton on the surface 

 and the inert Benthos at the base of the ocean, 

 be it shallow or deep, are a number of actively 

 swimming organisms mostly fish, but also cuttle- 

 fish, whales, seals, dolphins and porpoises, crus- 

 tacea, a few worms and medusae, and a certain 

 number of members of less well-known groups. 

 These forms are capable of swimming strongly 

 and making headway against effective currents 

 or tides and are collectively known as NEKTON. 

 They not only traverse wide stretches of water 

 in the same horizon, but they are capable of de- 



