CHAPTER XII 



THE FOOD OF ANIMALS— CARNIVOROUS ANNELIDS 

 AND SIPHON-WORMS 



We have next to consider typical carnivorous members of 

 the phyla Annelida, which includes Bristle- Worms (Chsetopoda) 

 and Leeches (Discophora), and Gephyrea (Siphon- Worms). 



BRISTLE -WORMS (Ch^topoda) 



All the members of this group have their bodies clearly 

 divided into a number of successive rings or segments, the 

 number of these varying in different cases. A further character 

 of importance is the possession of firm bristles or setcs, imbedded 

 in the sides of these segments, and sometimes very numerous 

 and obvious, as in the marine Annelids (Polychaeta), or else, 

 as in the terrestrial and freshwater Annelids (Oligochaeta), com- 

 paratively few in number. We are here only concerned with 

 the marine species, and for the present purpose it will suffice 

 to draw a distinction between the free-living or errant forms 

 which swim, creep, or it may be burrow, and sedentary forms 

 which inhabit temporary or permanent tubes of various kinds. 

 As one would naturally expect, it is among the former that are 

 included the typically predaceous species. A common kind, the 

 Sea - Centipede {Nereis), has already been described (vol. i, 

 pp. 425-429), and it is obviously specialized in accordance with 

 its carnivorous habits. A large field of activity is afforded by 

 the possession of several modes of locomotion — swimming, by 

 means of general undulations of the body; crawling and burrow- 

 ing, with the aid of blunt bristle-carrying foot-stumps arranged 

 along either side of the elongated trunk. As in predaceous 

 animals generally there are abundant sense organs serving to 

 detect prey. The foot-stumps are provided with tactile filaments 

 (cirri), and the well-developed head carries a number of feelers 



