THE HAUNTS OF LIFE 73 



Peculiar Conditions. — There are many peculiar haunts 

 of life which must be regarded as subdivisions of the main 

 haunts, though they have come to have very little in com- 

 mon with any one of them. Thus we find a peculiar set 

 of animals in the salt marshes which occur here and there 

 along the coasts ; in continental salt lakes which have 

 no connexion with any present sea ; in hot springs where 

 animals may sometimes be foimd flourishing at a tem- 

 perature of 45°C. 



II. The Pelagic Fauna 



The conditions of Ufe for open-sea or pelagic animals 

 must be regarded as on the whole very' favourable. For 

 there is plenty of room and there are no boundaries to 

 be dashed against till a shore is reached. A storm can 

 be avoided by sinking for several fathoms. There is sun- 

 shine without any risk of drought, and more uniformity 

 throughout the day and throughout the year than is to 

 be found elsewhere except in the monotonous abysses of 

 the deep sea. The extraordinary abundance of micro- 

 scopic Algse at the surface and down for many fathoms 

 ensures an inexhaustible food supply for the animals. 

 There is unlimited ' sea-soup '. It is not surprising, there- 

 fore, to find that the open sea has been peopled from the 

 earliest times of which the fossil-bearing rocks give us 

 any record. 



Dr. J. Y. Buchanan, who has given much attention 

 to the study of the colour of the sea, points out that a 

 deep olive-green, common in polar latitudes, but not 

 confined to them, is due to an abundance of diatoms and 

 to the excretions of animals that live on diatoms. From 

 the polar ice to beyond the fortieth parallel, the surface 



