NO. 9 MARINE INVERTEBRATES, ALASKA — MacGINITIE 25 



surf zone. Though few in species, these animals were washed out in 

 great numbers and many of the records of alongshore marine animals 

 were obtained by patrolling the beach after a windstorm. 



In winter, stations could be located exactly by survey lines run over 

 the ice, but in summer, because of the prevalence of fog, strong cur- 

 rents, and wind, it was much more difficult to go to a station or to 

 return to a former site. 



The northwest current, which turns north at Point Barrow, may 

 have a great deal to do with the deep channel that always exists at 

 Eluitkak Pass. The tendency to turn right, with back pressure from 

 the Beaufort Sea gyral, fills Elson Lagoon, and its only outlet is 

 through Eluitkak Pass. The channel that is dug every year by the 

 Arctic Contractors closes quickly because of the strong alongshore 

 current northeast toward the point. During the writer's stay at Bar- 

 row base, the heaviest swells and resulting heavy surf came from the 

 general direction of north-northwest to northwest. 



GENERAL DISCUSSION 

 DISTRIBUTION 



One of the main objectives of the study of the marine animals was 

 to determine the species common to Point Barrow and other regions 

 of the Arctic and those common to the Arctic and the North Atlantic 

 and to the Arctic and the North Pacific. 



Distribution is to a great extent dependent upon currents (see 

 "Currents"). However, currents are not the only major factor in- 

 volved. Most students of marine ecology fail to give due credit to the 

 vast scope of geological time for the role it plays in the distribution 

 of species ; they have had sufficient time — a billion years of it — to 

 spread to all similar parts of all oceans. Of course, not every species 

 will be found in every part of every ocean. Environments are so 

 different that speciation proceeds with adaptive deployment. If it 

 were not for environmental differences and habitat preferences, no 

 doubt all species would be found in every ocean. After all, most 

 phyla, classes, and orders are worldwide in distribution. Even some 

 species (see "Nemertea") are practically worldwide in their dis- 

 tribution, indicating a very stable inheritance. 



The concern here is with the distribution of Arctic Ocean animals 

 where environmental factors are the same, or nearly the same, for all 

 localities of the continental shelf. All species conform to the curve of 

 normal distribution for any factor and the curve is different for each 

 factor. Species of marine animals that have a wide range of tolerance 



