Gooseneck barnacles, Lepas anatifera, on a floating 

 bottle. (England. D. P. Wilson) 



The rose-colored acorn barnacle Balamis tintinnabulum 

 is one of the largest barnacles of the southern Cali- 

 fornia coast. It reaches a width of 2% inches and is 

 common on boat bottoms, wharf pilings, and rocks. 

 (California. Woody Williams) 



large shapeless mass. This bulbous extension be- 

 comes filled with eggs, which develop parthenoge- 

 netically to the nauplius stage and then escape to in- 

 fect more crabs. 



ISOPODS 



A number of other crustaceans, ranging from Vz- 

 inch to larger sizes, become familiar to many people 

 because they can be found alive or washed up on sea 

 beaches. Still other crustaceans thrive in damp places 

 on land far from any body of water. Under fallen 

 logs, stones, and even human possessions in many a 

 cellar, httle oval flattened crustaceans known as sow- 

 bugs or slaters are often common. They are members 

 of the order Isopoda, a name that indicates the var- 

 ious pairs of legs to be about equal in length. 



Many isopods take advantage of their flexibility to 

 curl up into a ball when disturbed. From this habit 

 they have acquired the name "pill bugs," and been 

 likened to miniature armadillos. Members of the 

 common genus Armadilliciiiim are particularly ready 

 to exhibit this method of self-protection. 



A pill bug of the seacoast is Ligici ( Plate 89 ) . Like 

 the more inland members of Oniscus and Porcellio, 

 it is more flattened and shows less tendency to curl 

 up. Sowbugs are all scavengers, a few reaching % of 

 an inch in length. Their gills are greatly reduced 

 but still serve in air for respiration. The females carry 

 a batch of eggs with them in a brood sac formed by 

 flat projections from the legs. 



In fresh waters, whether stationary or slowly flow- 

 ing, the isopods are represented by a 1-inch aquatic 

 sowbug, Asellus. It tolerates stagnation better than 

 many other creatures, and creeps over muddy bot- 

 toms eating refuse of all kinds. Females seem always 

 to be carrying eggs or a brood of recently hatched 

 young, with one generation succeeding another every 

 five to eight weeks from very early spring throughout 

 the summer. 



Around wharves in salt water, the cosmopolitan 

 wharf louse Idotea bcdtica is an isopod reaching a 

 length of 1 inch or more. It shows surprising agility 

 as well as awareness of its surroundings by expertly 

 dodging the fingers of small boys who try to capture a 

 specimen. It takes full advantage of its flattened body 

 by scuttling into crevices. 



The V'8-inch gribble Limnoria ligiuvwn goes even 

 farther by burrowing into submerged timbers, often 

 to a depth of half an inch or more, weakening docks 

 and other wooden shore installations. Often pilings 

 become eroded to an hourglass shape at low-tide 

 mark primarily from the activities of this isopod. 



AMPHWODS 



Whereas isopods tend to be flattened and broadly 

 oval, members of the order Amphipoda are more 

 usually compressed from side to side, and hence more 



