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seen inside its body. It is one of the things which cause 
the phosphorescence, or “ fox-fire,” of the sea. 
Ceratium is another small animal which is some- 
times extremely abundant in the sea. It forms a large 
portion of the food of some small fishes. 
Firtu Day. 
Copepods.—These are the most abundant animals 
in the sea. ‘They are very small animals belonging to 
the same class as the shrimp. Many young fishes live on 
them, and they are the principal food of many full-grown 
fishes like the herring and mackerel. 
A Copepod.—Magnified about 45 dia. 
The arrow worm isa little worm about an inch 
long. It is nearly always found in the sea. It forms 
part of the food of some fishes and it is said to eat fish 
eggs. 
Other common animals found in the tow-nettings. 
Food of marine animals.—tEverything in 
the sea lives on something smaller than itself. But this 
cannot go on without coming to a stop, and in the long 
