492 LIFE ON THE OCEAN SURFACE. 



the Sargasso Sea in the Atlantic, is well known. It is brown 

 when dried or preserved, but when living is of a very bright 

 yellow colour, which contrasts pleasingly with the deep blue 

 of the open Atlantic. Another seaweed {Fuciis vesiculosus) is 

 to be found also living free in the Atlantic, and the Giant Kelp 

 {Macrocystis pirifera), in the floating condition, ranges over a 

 wide l)elt of the Southern Ocean, as has been proved by Sir 

 Joseph Hooker.* 



All these seaweeds grow attached to rocks on various shores 

 as well as free, but none produce spores except when attached. 

 The Pelagic varieties multiply only by simple growth and sub- 

 division. A wide area covered with seaweeds corresponding 

 to the Sargasso Sea occurs in the North Pacific Ocean. 



Were it not for the existence of this vast Pelagic vegetation 

 the Pelagic fauna would be but a scanty one, since the debris 

 derived from the land could only support a small amount of 

 animals. Plants are as necessary in the open sea as on land 

 to form the starting-point of the organic cycle by building up 

 those compounds required by animals as food. The alga^, 

 though brown in appearance, contain and build up Chlorophyll, 

 the same green colouring matter as that which tinges the leaves 

 of our trees and plants on land, and which is now the only 

 starling-point and foundation-stone of life. 



The Sargasso Sea has its own fauna of animals specially 

 adapted to life amongst the Gulf Weed. Amongst these there 

 is a small fish, Antennarius, allied to the Angler, which has 

 long arm-like fore-fins with which it clings on to the bunches 

 of ^Veed. The fish makes a nest of the Weed, binding together 

 a glol)ular mass of it, as big as a Dutch cheese, by means of 

 long sticky gelatinous strings, which it forms for the purpose. 

 In the centre of the nest are deposited the eggs. 



The Weed is much encrusted by a Bryozoon {Membraiiipora), 

 which makes conspicuous white patches upon its surfixce. 

 Numbers of the detached air-vessels of the Weed are to be 

 seen floating about amongst the living Weed-beds, coated 

 entirely with the white Meinbranipora, and they look at first 

 like small globular Pelagic animals. 



All the inhabitants of the Gulf Weed are most remarkably 

 coloured, for purposes of protection and concealment, exactly 

 like the Weed itself. The Shrimps and Crabs which swarm 

 in the Weed are of exactly the same shade of yellow as the 

 AVeed, and have white markings upon their bodies to represent 

 the patches of Alembranipora. The largest shrimp occurring 

 has a dark brown colour with sharply defined areas of brilliant 

 white upon its surface, thus closely resembling the older darker- 



* " Flora Antarctica," Vol. I., pp. 464, 465. 



