GROWTH AND LIFE HISTORIES 



77 



the adult. The main diagnostic features of the various larval types 

 are connected with the stage of development of the various limbs 

 and their use in locomotion. The nauplius swims by means of 

 its antennae, and so does the protozoea, the zoea uses its thoracic 

 limbs for swimming, while the post-larval stage uses the abdominal 

 limbs, as does the adult penaeid. It is unfortunate that different 

 names were given to the stages of the Euphausiacea and the 

 penaeids, because it is now clear that the calyptopsis is a protozoea, 

 and the furcilia a zoea. while the cyrtopia can be regarded as the 

 first post-larval stage. 



Fig. 36. Larvae of Crabs. A, late zoea, in side view, 



note the chela already present. B, the same zoea viewed 



from behind to show the way in which the stalked eyes 



protrude and give an all round view. 



Most of the decapods miss out the naupliar stages and hatch as a 

 zoea, which may sometimes be heavily ornamented with spines. 

 The zoea of a crab (fig. 36A-B) changes into a megalopa (fig. 36c), 

 which is just like a little crab with its tail extended behind it. 

 The equivalent stage of a hermit crab is called a glaucothoe. 



Peculiar larvae are produced by the Palinura. The body of the 

 larva is flattened and leaf-like (fig. 37), so that the name phyllosoma 

 has been given to it. Recent work has shown that the California 

 spiny lobster, Panulirus inter rn plus, goes through eleven phyllosoma 

 stages, then changes into a small lobster-like creature with long 



