782 DEPTHS OF THE OCEAN chap. 



the cachalot is the principal, if not the only, large species 

 which has been the object of man's exertions in these 

 parts. 



The distribution of whales, here roughly outlined, seems to 

 agree very well with what I have previously stated in regard 

 to the distribution of pelagic animals. In boreal, and probably 

 also in antarctic, waters the abundance of minute pelagic 

 animals (plankton) in the upper layers is particularly character- 

 istic of certain seasons of the year, and for this reason the 

 whalebone whales have their habitat in these waters. In coast 

 waters the plankton is equally rich in many places, along with 

 quantities of small pelagic fishes, herrings, sprats, pilchards, 

 etc., which are the food sought by humpback whales. 

 Whether the various right whales, like BalcEna biscayensis, in 



Fig. 574. 

 Balcrna biscayensis. (From Guldberg. ) 



southern waters eat the small herring species besides the 

 plankton is unknown to me ; in boreal waters I am only aware 

 that plankton has been found in their stomachs. 



In the open ocean the plankton is scarce in the upper layers, 

 but the deeper layers contain multitudes of large crustaceans 

 and squids, and here only squid-hunting whales like the cachalot 

 are found in numbers. Enormous diving power is peculiar to 

 the cachalot and its ally, the bottle-nose. One of our most 

 experienced bottle-nose whalers has told me how the whale 

 "sounds" when struck by the harpoon, very often diving 

 straight down, taking out as much as 400 fathoms of line in a 

 perfectly vertical direction. It is very interesting to note that 

 on our Atlantic cruise we found many proofs of the existence 

 of quantities of squid in vast areas of the open ocean, partly 

 belonging to the same species as the Prince of Monaco found in 

 the stomachs of sperm-whales. The occurrence of these whales, 

 and the importance of the sperm-whaling carried on in the open 



