208 THE WORLD OF THE SEA. 
the smaller species they protrude and hang like a fungus into the 
water. Occasionally these organs serve the double purpose of 
breathing and swimming. However, sometimes, the animal has no 
special respiratory organs. 
Nearly all the crustaceans are strong, hardy, and destructive. 
They are the marauders of the ocean community, merciless 
A SEA-SPIDER. 
(Pisa tetraodon.) 
brigands, ready to do anything to secure their prey. .They fight 
in deadly combat, not only with their enemies or their prey, but 
with each other, and frequently without any pretext, save only for 
the love of battle. It is useless for the assailant to shower his 
blows upon the carapace of his adversary; but when with his 
powerful pincers he seizes the long slim feet, the tail, or the delicate 
antenne, then he wounds and dilapidates his foe. Yet the 
vanquished crustacean is not maimed for life ; in a few weeks the 
mutilated members recover themselves, and those which were 
actually pulled off are again renewed. This explains the fact that 
