CHAPTER XIV 



THE FOOD OF ANIMALS— CCELENTERATES, SPONGES, 



AND PROTOZOA 



Passing downwards in the animal scale we come to the in- 

 numerable marine forms, often of extreme beauty, which are 

 grouped together in the phylum Coelentera, and include 

 Zoophytes, Jelly-Fish, Sea-Anemones, Corals, and Comb-Jellies. 

 Three classes are recognized: — (i) Ctenophora, Comb- Jellies; 

 (2) Anthozoa, Sea- Anemones and most Corals; (3) Hydrozoa, 

 Zoophytes, Jelly-Fish, and some Corals. The creatures em- 

 braced by these three classes are all actively predaceous, and 

 the methods of capturing prey will be described with reference to 

 a few typical forms. 



COMB-JELLIES (Ctenophora) 



A common British Comb-Jelly, Cydippe (see vol. i, p. 483), 

 has a translucent body shaped like a small melon, which is rowed 

 through the water by eight longitudinal rows of little paddles, 

 which suggest by their appearance the teeth of a comb, hence 

 the word Ctenophora (Gk. cteis, a comb; phSro, I carry) and 

 its popular equivalent. The digestive organs are represented by 

 a complicated system of canals traversing the jelly-like body, and 

 opening by a mouth at the end which is kept hindermost during 

 swimming. Two long branched tentacles protrude from pouches 

 in the side of the body, and can either be extended to a rela- 

 tively great extent or else withdrawn altogether from the surface. 

 These tentacles are veritable fishing-lines which capture the food, 

 consisting largely of minute crustaceans, by means of innumerable 

 minute sticky knobs with which they are beset. Should the 

 victims attempt to escape they are " played " by the straighten- 

 ing out of the elastic spiral stalks with which these knobs are 

 provided, and when exhausted are conveyed to the mouth. 



