99 



o • XT u Number _ 



Station Number ^ ■, :,■ -, , Species 



or Inaividuals 



111 None living 



1 13 Total 1 Olivella anazora (G) 



114 1 Olivella fletcherae (G) 

 1 Megapitaria aurantiaca (P) 

 1 Transenella puella (P) 

 3 Macoma, sp. (juv.) (P) 



Total 6 

 P = Pelecypod G = Gastropod. 



Only 36 living specimens of mollusks were taken in these eight small- 

 sized samples: no other groups have been identified yet from these stations. 

 If these samples cover 1/20 m^ each or a total of 2/5 m^ the average number 

 of animals per square meter is roughly 90. This figure is not too reliable, 

 since not only is the total area sampled insufficiant, but the distribution 

 of animals is very patchy in this environment. This can be seen by the 

 variation in the number of individuals in the eight stations. The majority 

 of the living individuals of mollusks from these stations were very small, 

 and almost juvenile in size. 



A preliminary appraisal was made of the feeding types among the 

 invertebrates of the near shore, sand-bottom assemblage. The dominant 

 feeding type among the lamellibranchs appears to be suspension feeding, 

 which was also observed by Sanders (1958), Savilov (1961) and McNulty, 

 Work and Moore (1962). This would seem logical, since the nearshore 

 zone is characterized by continual turbulence and longshore current 

 transport, bringing in an abundant supply of suspended organic matter 

 and living organisms held in suspension. The abundance of light in this 

 zone also produces a large supply of phytoplankton, one of the principal 

 sources of food for suspension feeders. Predators comprise the greatest 

 proportion of gastropods, and as such they are probably dependent upon 

 the large lamellibranch population. 



The relatively few deposit-feeding mollusks can be attributed to the 

 probable lack of organic detritus, which is not apt to collect in the con- 

 tinuously agitated and well-sorted sand, so typical of this environment. 

 Most of the lamellibranch larval shells examined indicated that the majority 

 of species have a pelagic development while many of the very large proso- 

 branch gastropods have large, egg-capsuled produced larvae which can 

 probably withstand the turbulence so typical of these waters. The fact 

 that so many of the inhabitants of the sand-flat environment are very 

 active animals and have a long pelagic development may explain the great 



