CHAPTER IX 

 Feeding of Marine Animals 



Food is the first necessity of life, and nowhere is the struggle 

 to obtain it keener than in the sea ; every possible source 

 of food has been exploited by one tj^'pe of animal or another, 

 so that the study of the multitudinous devices for obtaining 

 food of one sort or another which have been evolved as a 

 result of the keen struggle for existence forms one of the 

 most fascinating branches of marine biology. 



The food in the sea may be divided into two groups ; 

 there are the dissolved salts and gases in sea water, such as 

 the manurial nitrates and phosphates, carbonic acid gas, 

 etc., which form the food of plant life, both large seaweeds 

 and microscopical diatoms ; and there are the actual plants 

 and animals themselves, both living and dead, and also 

 while in the process of disintegration by bacteria. It is the 

 organic substances of which these are made up — as opposed 

 to the inorganic salts in the sea water — which form the food 

 of the animals. They are divided into three groups of 

 substances, fats, proteins and carbohydrates, all three of 

 which — together with minute traces of those little known, 

 but all-important, substances known as vitamins — are 

 essential to the life of the animal, though the relative 

 proportions vary for different kinds of animals. According 

 to a German scientist named Piitter, the animals also obtain 

 nourishment from dissolved organic substances in the water, 

 but this somewhat fascinating theory has never been fully 

 proved. 



One may roughly divide animals into herbivores, carni- 

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