58 
DEEP-SEA LAMPS 
features of life in the ocean abyss, that its inhabitants 
show so little visible change of structure to meet what 
seems the first and most overwhelming change of 
physical conditions. The angler-fish and eels, crabs 
and prawns, star-fish and zoophytes of the shallow 
waters are represented in the abyss by forms almost 
similar in structure, though that some difference must 
exist is shown by the fact that when brought up by 
the dredge from the depths of the ocean they are 
killed and distorted by the diminution and disappear- 
ance of the vast pressure in which they habitually 
live. “ The fish which live at these enormous depths,” 
writes Mr. Hickson, “are liable to a curious form of 
accident. If, in chasing their prey, or for any other 
reason, they rise to a considerable distance above the 
floor of the ocean, the gases of their swimming-bladder 
become greatly expanded, and their specific gravity 
reduced. If the muscles are not strong enough to 
drive the body downwards, the fish, becoming more 
and more distended as it goes, is gradually killed on 
its long and involuntary journey to the surface of the 
sea. The deep-sea fish, then, are exposed to a danger 
that no other animals in this world are subject to — 
namely, that of tumbling upwards.” 
But however obscure the structure which enables 
the deep-sea creatures to withstand the pressure of the 
waters, the means by which they combat the plague 
of darkness is evident and astounding. It is well 
known that the number of phosphorescent animals, 
even in shallow tropical seas, is such that they can 
