22 
THE BOOK OF FISHES 
HOW A CRAB DISCARDS ITS OUTGROWN OVERCOAT 
The difference between a hard-shell and soft-shell crab is simply one of time. Every now and then 
the crab needs to grow a little, so its body gets soft and its hard shell splits open. It is then enabled to 
pull itself out of that shell and to grow while a new one is in the process of forming. When this process 
of growing and hardening is completed, it ceases to be a soft-shell crab and once more joins the ranks of the 
hard-shells. This change takes place several times a 
conceivable pressures prevail, the miracle 
of life still goes on! 
In some of the ocean depths the pres¬ 
sure exerted would be equal to that of a 
block of limestone three feet square and 
six feet high resting on a square inch of 
surface. A creature five feet long with 
an average girth of four feet would have 
to sustain a pressure of some 20,000 
tons. 
In size the denizens of the deep seas 
range from microscopic to mammoth 
creatures. Occasionally huge hulks of 
season. 
flesh of a tough, fibrous nature, unlike 
that of any known creatures, are washed 
ashore. One such hulk was 20 feet long, 
40 feet around, and weighed many tons. 
It was believed to be a fragment of some 
giant of the sea floor, torn loose by a cat¬ 
aclysm of the deep. 
RELATIVE AREA AVAILABLE TO MARINE 
AND LAND FAUNA 
The area of the sea is three times that 
of the land. Its average depth is more 
than two miles. The sea has 138 times 
