ZONES OF THE SEA-WHERE THEY LIVE 17 



Atlantic Temperate. Atlantic temperate waters lie from Cape Hatteras north 

 to Cape Cod where the Labrador Current ends its southward flow. At Cape Cod 

 the mean annual temperature is 46" Fahrenheit and the extremes are 37° in 

 winter to 66° in summer. 



Above Cape Cod is a zone reaching to Labrador that may be called cold 

 temperate, boreal, or subarctic. This is the home of the sculpins, halibuts, 

 rock eels, and of huge schools of cod and herring among others. 



East Pacific Temperate. The temperate Pacific lies from San Diego to the 

 Gulf of Alaska. This is a very uniform zone, both in temperature and in flora 

 and fauna, throughout its whole length. Ekman (1953) lists the following 

 August temperatures for this zone: San Diego 64°, San Francisco 55° to 61°, 

 Seatde 61°, and the Gulf of Alaska 57°. The reason for this uniformity is that 

 upwelling cools the southern part and warm currents warm the northern part. 

 The winter temperatures show much greater variation, however, being much 

 colder to the north. 



This region has a verv large per cent of endemics. Ekman (1953) lists the 

 surf perches, greenlings, and rockfishes QSehastodes^, and there are many 

 others. Starfishes are more greatly varied in this region than anywhere else in 

 the world. There are 92 species of them, of which 60 per cent are endemic. 

 The sun star, Pycnopodia, is the largest of all starfishes. 



The boreal or subarctic Pacific is similar to that of the Adantic with its cod, 

 halibuts, rock eels and sculpins. It extends from the Aleutian Islands north to 

 the Bering Strait. 



Boreal waters in general contain the greatest schools of fishes in the seas. 

 Colder waters have fewer kinds of animals and plants than warmer waters, 

 but this does not prevent those few species from reaching immense numbers 

 in the summer when light is strong, days are long, and surface waters are still 

 cool and viscous enough to support plankton. These constitute ideal conditions 

 for plankton and when they are combined with the upwelling near the 

 Labrador coast, which brings nourishment in the form of dissolved salts to 

 the surface, it is not too hard to see why life is so abundant there. Boreal seas 

 are further characterized by immense beds of algae, rocky shores, and the world's 

 highest tides. 



ARCTIC SEAS 



Waters of the arctic zone never get warmer than 41° to 45° in summer and 

 reach these heights only for short periods. Ice is an ever-present characteristic 

 whether in floe or iceberg form. These waters are present north of the Bering 

 Strait and Labrador. In general, the boreal animals and plants are also found 

 here, and among them are sculpins, blennies, sea snails, and dense beds of 

 brown algae. Tides are high and shores are rocky in this zone. 



Substrate Zones 



On land, the word "substrate" usually refers to the ground under our feet, 

 since it forms the support of most terrestrial animals and plants. But in the 

 sea, "substrate" may refer either to the ocean bottom or to the water itself since 

 both are dense enough to support life. (In subsequent chapters, "substrate" is 



