116 ANIMALS OF THE SEASHORE 



SIPULCULOIDEA 



Unsegmented worms usually made up of two 

 divisions — a slender head portion (introvert) which 

 can be retracted within a thicker posterior portion. 



Phascolosoma gouldi Pourtales 



PLATE XII! Fig. 8 



About 6 inches in length; occasionally dredged 

 off the New Jersey coast. 



2. Segmented Worms 



The segmented worms (Annelids) are composed 

 of a series of ring-like segments, each segment con- 

 taining a complete set of internal organs. The most 

 conspicuous marine annelids belong to the class 

 Polychaeta (meaning many bristles). These worms 

 possess a pair of leg-like structures (parapodia) on 

 each segment; on each parapodium there are numer- 

 ous bristles (chaetae) usually in two bundles. 



The annelid worms are much higher in the scale 

 of animal life than the unsegmented worms. They 

 have better sense organs, a well developed nervous 

 system as well as a digestive system and blood 

 vessels. 



Most annelids burrow in the sand or mud; some 

 build tubes of sand or shell. Certain species can be 

 found swimming on the surface of the sea especially 

 at night. Some worms are carnivorous, while others 

 are vegetarian. Many ingest mud and obtain their 

 nourishment from the minute organic particles in- 

 cluded therein. 



Another group of annelids, the Oligochaeta, in- 



