Animal Life by the Sea-shore. 



shell, the lobster seeks shelter in holes, its presence being often 

 betrayed by the empty armour lying in proximity. 



This moulting or ecdysis is rendered necessary by the hard 

 nature of the outer covering of the body and limbs, an armour, 

 secreted by the skin, which, being incapable of increasing in size, 

 must be cast off entire as the underljring soft tissues grow (Fig. 38). 

 Considering the small calibre of the basal segment through which 



FIG. 38. HOW A MOULTING LOBSTER WITHDRAWS THE MUSCLES 



FROM ITS CLAWS. 



the fleshy parts of the enlarged claw of many crustaceans have 

 to pass in this moulting operation, the process seems wonderful, 

 but is explained by the fact that, just before ecdysis, the water 

 and blood which swell the muscular part are withdrawn and 

 cause the tissues to shrivel up to such an extent as to allow 

 its being forced through a narrow opening. The parts of the 

 limb are very much distorted immediately after their release, 

 but they soon resume their natural form with a proportionate 

 increase in size. A diagrammatic sketch of a lobster's claw is 

 here given to make the explanation clearer. In this sketch the 

 fleshy or muscular part of the claw, just before the moult, is 

 represented by a dotted area, showing how this part shrivels to 

 insignificant proportions in order to pass through the small 

 calibre of the basal segments. As soon as the animal is released 

 from its shell, the claw becomes turgid with water and blood, and 

 m a very short time swcUs out to even a larger size than before. 



