OCR Text |
Show 182 INVERTEBRATES Phylum Anthropods Anthropods are the most conspicuous and apparently the most abundant group of animals in the Great Salt Lake. The brine shrimp ( Artemia salina Syn. gracilis Verrill) and brine flies ( Ephydra gracilis Packard, and Ephydra hians Say) are the members of the phylum present in the Lake. The brine shrimp is a free- swimming crustacean approximately ten mm. long whose color varies from a light blue- green to a light reddish brown. Females both lay eggs and give birth to live young. Summer eggs are soft- shelled and hatch within a few hours of being laid. Winter eggs are hard- shelled and must dry before hatching. They are able to withstand cold temperatures and long periods of drought ( Talmage, 1900) and wide variations in water composition ( Jensen, 1918). Adult brine shrimp are abundant along shorelines during summer months. Gladys Relyea ( 1937) states that when water temperatures drop below six degrees Centigrade, the adult shrimp die, leaving the winter eggs to replace them in the spring. Brine flies are dark flies three to six mm. long. During the summer, brine flies are abundant in the Lake waters as larvae and pupae and over the Lake surface and shores as winged adult flies. Aldrich has estimated the population of brine flies at 25 per square inch or 370 million flies per mile of beach. ( See Brine Flies in " Noxious Insects," p. 185.) Phylum Protozoa Little is known concerning the protozoans in the Great Salt Lake. |