Bullock (1953) has reported upon predator recognition and escape 

 responses of some intertida! gastropods in the presence of carnivorous sea 

 stars on the west coast of the United States, and states that a number of gastro- 

 pods exhibit specific patterns of escape. However, a muricid carnivorous snail, . 

 Acanthma, which he studied displayed no such response . A similar study of the 

 predatory -prey relationships of Asterias and Urosalpinx should prove illuminating 



Fish 



Goode (1884) was informed by a bayman in New York that in the years when 

 eels ( lAnguilla rostrata) were plentiful, the oyster drills were "kept down" because 

 the eels fed on their egg cases , This observation has never received confirmation, 



Oystermen in Delaware Bay reported to Stauber (1943) that toadfish 

 (Opsanus tau) consume drills, so he examined the stomach contents of a number of 

 them. In every case but one he found that the drill shells therein contained hermit 

 crabs ( Pagurus longicarpus ) in the process of digestion. McDermott (1952) durir.g 

 the summer of 1952 analyzed the stomach contents of 37 toadfish, also collected 

 in Delaware Bay, and encountered only the empty shells of two Urosalpinx . He 

 reports that small Crustacea constituted the bulk of organisms in these stomachs 

 It would seem that these fish are not predators of the oyster drill. 



Parasites 



Stunkard and Shaw (1931) record the presence of the larval trematode 

 Cercaria sensifera in Urosalpinx in the Woods Hole, Massachusetts, area; and 

 later Cole (1942) found the same parasite in a single drill from the River Black - 

 water, England. Stauber (1941) has reported the presence of an ectoparasitic 

 polyclad turbellanan, Hoploplana inquilina thaisana ,in the mantle cavity of drills 

 in Delaware Bay. In addition Cole (1942) found the digestive diverticulum of a 

 number of drills in the River Blackwater parasitized by an unknown arthropod, 

 probably an isojiod. No mortality has been associated with the presence of these 

 parasites There are no reports on the possible role of these parasites in the 

 biological control of the drill . 



MIGRATION 

 Horizontal 



Since U. cirerea lacks a free swimming larval stage, it depends entirely 

 on its own slow rate of creeping or upon transportation by human or other agencies 

 for its distribution. Much interest has developed during the last 20 years, particu- 

 larly in oyster culture, on the rate and extent of migration of this species in the 

 field The first to apply an experimental approach to this problem was Federigm 

 (1931c). 



90 



