108 New York State Museum 



they and the green seaweeds thrived in practically fresh 

 water, the copepods increasing greatly in numbers and 

 being very active. Under conditions of evaporation the 

 copepods live until the water is almost entirely gone, seek- 

 ing refuge within the green seaweed after evaporation has 

 been going on for some time. Salt marshes show even 

 more variability in salinity of water than the rock pools 

 and require similar powers of resistance for the life in- 

 habiting them. One of the most extreme adaptations to 

 strong saline conditions is illustrated by the Brine-shrimp 

 (Artemia salina), which lives in brine pools. This is 

 a small, shrimplike form that inhabits European salt 

 marshes (Lorraine; Cagliari, Sardinia), resisting densi- 

 ties as great as one to 16 or one to 23. In the country 

 around Cagliari there is a gray salt used, in which are 

 found the eggs of this crustacean. These eggs will de- 

 velop normally when in water of suitable salinity. 



Conflict between animals themselves. Not only is 

 there the struggle of the shore animals to adapt them- 

 selves to the physical conditions of their environment, 

 but there is also a sharp conflict between the animals 

 themselves which has led to methods and weapons of 

 attack and defense. Some form of protective armor is 

 of frequent occurrence along the shore, such as the 

 shells of mollusks, the spines of sea-urchins, the tubes 

 of worms, the tests or shells of crustaceans etc. Crus- 

 taceans, such as lobsters and crabs, have chelae or 

 pincers as weapons of defense; hydroids, jelly fishes 

 and sea anemones have stinging capsules or nemato- 

 cysts for paralyzing their prey; mollusks, otherwise 

 defenseless, have the strong adductor muscles that 

 close the shell. There are boring gastropods that prey 



