CH. Ill] LIFE IX THE SEA 63 



proportion of matter capable of serving as food for the deep-sea 

 benthos. The abyssal deposits therefore serve as a kind of " pap " 

 which is eaten by the bottom-living animals for the sake of the 

 nutriment it contains in much the same kind of way as a lugworm 

 eats the sand, or rather passes this through its intestine and digests 

 and absorbs the small proportion of organic substance which the 

 sand contains. These ooze-eating animals are then the prey of 

 others, and since the deep-sea fauna is to a great extent a 

 predatory one we find that many of the abyssal Crustacea are 

 provided with queer organs of attack and defence : tactile, 

 prehensile and alluring contrivances, all used in the effort to 

 obtain food or in that of resisting the attacks of their enemies. 

 Some Crustacea for instance are of enormous size when compared 

 with their shallow water allies, and many deep-sea fishes have 

 enormous heads furnished with great mouths armed with formid- 

 able teeth, while their stomachs are large and the bodies and tails 

 are small and fragile. Although daylight never penetrates to the 

 bottom of the deep sea it is still the case that eternal darkness 

 does not prevail, for many of the abyssal creatures are phos- 

 phorescent. Fishes may have rows of luminous organs, and some 

 have a kind of bull's-eye lantern from which a stream of light can 

 apparently be thrown at the will of the animal. Probably a kind 

 of diffuse light is present in the deep, and at any rate animals 

 may be visible by means of their own phosphorescence as they 

 move about. Some are blind but others have large eyes. Associated 

 with the phosphorescence are the prevailing colours of deep-sea 

 animals. Glaring reds and browns prevail and generally monotones 

 are the rule, and the diversified colours of the upper world are 

 absent. Curious problems arise in the consideration of the mode 

 of life of these creatures. How is it, for instance, that they can 

 withstand the incredible pressure of the superincumbent layers of 

 water ? This is a question which has never been properly 

 answered. Experiments with ordinary marine animals subjected 

 to enormous pressures seem to shew that profound bodily distur- 

 bance results from this. The first effect of increasing pressure is 

 the excitation of the nervous system and then follows the inhibition 

 of the functions of this. The animal is thrown into a state of 

 coma from which it recovers if the pressure is released and if it 



