Mouth 



^—Tentacles 

 Hooks 



Introvert 



Trunk 



.Anus 



Esophagus 



Ventral 

 Nerve Cord 



Nephridium 



Gut Coi 



Right Dorsal 



Retractor 



Rectum 



Right Ventral 

 Retractor 



Figure 1.— General morphology- of Sipuncula. A. External form of Phascolion 

 BtrombL B. Internal form of Phascolopsis gouldi. 



Holdfasts 



exception of G. minuta, sipunculans are dioecious and 

 lack any sexual dimorphism. The gametes are retained in 

 the coelom until mature then released through the neph- 

 ridiopores, fertilization occurring externally. Free-swim- 

 ming trochophore larvae generally occur but some 

 brooding of early stages within the maternal "home" 

 (crevice or hole in substrate) has been observed in G. 

 minuta and may occur in other cold- or deepwater forms. 

 After metamorphosis, the juveniles settle onto a suitable 

 substratum and probably remain in that immediate 

 vicinity throughout their lives. Our knowledge of growth 

 rate or longevity is nonexistent. 



Sipunculans are either filter or deposit feeders, depend- 

 ing on the species. The filter feeders have a more elabor- 

 ate tentacular apparatus than the deposit feeders. As 

 such, these worms play their part in the recycling of detri- 

 tus and probably consume smaller invertebrates in the 

 process. They are in turn preyed on by fish and probably 

 other predators. It has been reported in the literature 

 that sipunculans are used as food for man in Indonesia 

 and the Indo-Pacific (Hyman 1959) and are also used as 

 fish bait in these regions. 



The methods for collecting Sipuncula vary according 

 to the area. Phascolopsis gouldi can be collected with a 

 shovel at low tide; in warmer waters intertidal forms 

 often inhabit coral or rock which must be carefully 



broken with a hammer. To collect the deeper dwelling 

 species a dredge or trawl is required. These should be 

 equipped with a fine mesh bag (less than 2 mm) to retain 

 the smaller individuals. The sediment is then gently 

 washed through a sieve (1 mm or less) and the remaining 

 material inspected with a dissecting microscope. Initial 

 fixation should be with 4 f 7 formaldehyde but, if pos- 

 sible, should be preceded by a 30-60 min period of nar- 

 cotization with a compound such as menthol crystals or a 

 dilute solution (5-10^) of ethanol and seawater, to allow 

 the introverts to protrude. This greatly facilitates iden- 

 tification. For long-term storage 70"^ ethanol should be 

 used. 



In order to identify most animals to species, dissection 

 is required. The recommended procedure is to find the 

 dorsal anus and make an incision down the dorsal side 

 passing just to the left of the anus, thereby avoiding the 

 internal organs. 



Hyman ( 1959) gave a general account of the biology of 

 the sipunculans. Gerould (1913) and Cutler (1973) have 

 discussed the western North Atlantic fauna in more 

 detail. Stephen (1960) has brief descriptions of all these 

 species except Phascolopsis gouldi. Stephen and Ed- 

 monds (19721 presented the most comprehensive treat- 

 ment of the phylum, but it is not without error. Theel 

 (1905) contains good illustrations and descriptions of all 

 the species discussed here except for P. gouldi. Stephen 



