THE GREAT DEEPS 117 



In rare cases it may be that organic matter 

 in the water is simply absorbed by the animal's 

 body without any direct " feeding" at all, or it 

 may be wafted into the mouth by tentacles and 

 cilia, or it may simply sink into capacious open 

 mouths, as in the case of abyssal sea-anemones. 

 But many of the animals living on the ocean- 

 floor are " mud-eaters," and as the rich " ooze " 

 passes through their food-canal the organic 

 matter it contains is digested. The same thing 

 happens in the case of the common earthworm 

 as it eats its way through the soil, or in the 

 case of the lobworms on the sandy beach. 



It may be asked how we know what deep- 

 sea animals eat since we cannot of course 

 actually see what takes place in the dark 

 abysses. The answer is that the contents of 

 the food-canal can be studied in animals 

 dredged up, and also that we can carefully 

 compare those that are brought up in the 

 dredge with their near relatives living under 

 different conditions, and try to make out what 

 the differences between them may mean. 



Thus it is certain that many of the fishes at 

 the bottom of the sea are voracious flesh-eaters. 

 Some of them are of the usual wedge-shape, 

 with long tails, but a great many are quite 



