288 THE FISHES OF THE NORTHERN SEAS 



The floras of the cool temperate waters of the North Sea and Baltic have also been 

 well investigated, and, since they are somewhat dissimilar, they may be taken as 

 two representative northern types. As in all cool temperate waters, the brown 

 seaweeds are predominant in size and quantity in both areas, the well-known 

 bladder-wrack (Fucus vesiculosa) being chiefly characteristic of the upper zone of 

 the rocky coast region, while the allied F. serrata, together with several other 

 species characterised by their broad leaves, grows in deeper water. There are 

 a number of other brown algae, the thread-like group being rich in variety of form, 

 whereas the red seaweeds are less abundant and varied, as they are in some localities 

 in the Mediterranean. Of the green seaweeds there are but few forms, while the 

 sea-grasses are only represented by the common grass-wrack (Zostera marina). 

 Wide stretches of the rocky bed of the Baltic are covered with bladder-wrack, the 

 most varied and luxuriant growth being found in the lower zone. On the other 

 hand, the sandy and muddy bottom of the quiet bays presents a somewhat 

 monotonous picture, being covered with sea-grasses down to a depth of 5 fathoms. 

 The scantiness of the Baltic flora is attributed to the small amount of saline matter 

 contained in the water, this sterility being most pronounced in the west and east 

 where the water is the least salt. In these shallow seas the general growth in 

 winter is much weaker than in summer. In spring the chalky ridge lying off the 

 north of Heligoland is covered with fresh green seaweed, and farther on, near the 

 edge of the surf, with the yellowish brown leaves of the tangle (Laminaria). In 

 May these seaweeds are replaced by a dark red species, which disappears entirely 

 in July ; and in August and September the rock is covered with a brown robe, 

 only to become bare once more with the approach of winter. 



In the cooler southern seas the most remarkable seaweed is the giant 

 Macrocystis pyrifera, which grows to a length of 1000 feet and exceeds all other 

 ocean plants in size. Although the northern species of bladder- wrack has not 

 been observed in southern waters, the group is represented by a few species in 

 the vicinity of the Auckland Islands, where there are none of the sea-grasses so 

 common on the coasts of Australia and New Zealand. The Antarctic and Arctic 

 Oceans far surpass all the rest in the rich development of their vegetation, the 

 brown and red seaweeds predominating, while sea-grass is absent. 



The pelagic, or floating flora of the ocean, consists mainly of microscopic 

 organisms, most numerous within 100 fathoms of the surface. On the actual 

 surface but few plants thrive, among these few being Trichodesmum erythramm, 

 which by its abundance and red colour gives the name to the Red Sea. 

 Bass and sea- Among the animal inhabitants of the ocean, fishes claim the most 



Perches. important position. In the sea dwell the greater number of the bony 

 fishes, among which the first place is now generally assigned to the perch tribe. 

 Closely allied to the true perches, which inhabit slightly salt as well as fresh water, 

 are bass and sea-perches. Among these one of the most familiar is the common 

 bass (Labrax lupus), which attains a length of 18 inches or more, and is fairly 

 common in European seas. In appearance this fish is like a slender perch, slaty 

 blue above and silvery below, with a dark spot on the gill-cover beneath the 

 spines, while the paired fins are yellowish and the median fins grey. The group 

 is confined to the North Atlantic and its branches and affluents ; but the allied 



