A TALK ABOUT CRABS 
103 
Nautilus stage. But only certain species of 
crabs pass through this stage, others emerging 
from the egg in a more advanced form called 
a zoea. 
The zoea of the common, green, or shore- 
crab is a most extraordinary looking object. 
Its head, from the top of which arises a long 
and upstanding spine-like growth, is very 
large in proportion to the rest of its body, 
while its “ face ” terminates in an elongated 
and sharp beak. The eyes, moreover, are 
remarkable for their enormous size. 
When once the larva has completed its 
metamorphosis and assumed the crab form, 
it sheds its shell periodically so long as it 
continues to grow. If it did not do this the 
creature would be unable to increase in size 
owing to the hard and unyielding shell pre¬ 
venting the body from developing. 
No hard-and-fast rule applies to the intervals 
between the moulting periods, a great deal 
depending upon the amount of food the crab 
is able to obtain, and the consequent rate of 
its growth. It is interesting, however, to give 
records in regard to a specimen kept in cap¬ 
tivity, the first change taking place on April 
11, the second on May 22, a third on July 3, 
a fourth on August 30, and another on Sep¬ 
tember 21. 
