CHAPTER XXII 



ALLIES OF THE EARTHWORMS : ANNELIDA 



Sinuous, glittering worm of the sea, 

 Wondrous in sheen of ruby and green. 



The Sandworm. One of the commonest of the animals liv- 

 ing in the mud and sand at tide level in protected bays and 

 inlets of all the oceans is the sandworm, known more defi- 

 nitely by its scientific name Ne'reis vi'rens (Fig. 131). It 

 lives in burrows lined with a thick mucus. This unites the 

 grains of sand into a tough, black tube. The depth of these 

 burrows depends on the length of the animal, which is 

 sometimes as great as two feet. Like earthworms, sand- 

 worms often rest with the head near the opening during the 

 day. Sometimes at night they leave their burrows to swim 

 at the surface. It is likely, however, that in most cases they 

 do not withdraw the entire body from the burrow, but 

 reach out in all directions for prey that comes near them. 

 When driven from their burrows in the daytime they swim 

 away, and at that time look very beautiful, as the couplet 

 above suggests. Nereis has two horny jaws, sharp-pointed, 

 and bending to meet at the tips. The jaws are concealed by 

 the infolded pharynx when not in use. When about to 

 seize its prey, which consists chiefly of small, living sea 

 animals, the sandworm suddenly everts the pharynx, and 

 the jaws, thus freed, at once spread horizontally and seize 

 the victim. 



Comparison of the external appearance of the sandworm 

 with that of an earthworm brings out some points of differ- 

 ence, as well as some points of similarity. We observe the 



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