^^"^ ZOOGENESIS ^8^ 



eye. These float suspended in the water all the way 

 from the brightly illuminated surface down to the 

 greatest depths at which they are able to secure 

 enough effective light to enable them to grow. 



So life in the sea for the most part is supported by 

 plants which are invisible to us. This gives us the 

 impression as we view the sea at some distance from 

 the land that all sea life is animal life, consisting of 

 fish, jellyfish (fig. 3, p. 5), whales, porpoises and 

 other creatures. Conditions in the sea may perhaps 

 best be understood if we compare the sea, in its 

 richest portions, to a sort of fog or mist in which each 

 little particle is a minute plant. 



Many different kinds of creatures feed upon these 

 little plants. Of these the most important and most 

 numerous are various minute crustaceans of the sort 

 known as copepods (fig. 64, p. iii). Crustaceans be- 

 long to the same group (Arthropoda) as the insects, 

 and it is interesting to find that in the sea crustaceans, 

 as on the land the insects, are the chief plant feeders — ■ 

 at least the chief plant feeders which serve as food for 

 other types of life. 



Drifting about suspended in the water swarming 

 with minute plants, and the crustaceans and other 

 creatures feeding on them, are many other types of 

 animals, such as many kinds of jellyfishes (fig. 3, 

 p. 5) and the curious arrow-worms (fig. 6i, p. iii) 

 and pyrosomas (fig. 59, p. iii) which thus exist sur- 

 rounded by and suspended in their food supply. And 

 together with these live many creatures possessed of 

 powers of active locomotion, especially squid (fig. 45, 



