240 



ANNELIDA AND ARTHROPODA: 



Figure 14.14 Class Crustocea. Subclass Maiacostraca. Order Decapodo: 1, Cancer, a crab 

 (x '4), marine; 2, Pogurus, a hermit crab (x ' ^>), morine; 3, Emerita, a sand crab, to the left a small 

 femole carrying eggs under her reflexed abdominal plate, to the right a top view, marine; 4, Crogo, a 

 shrimp (x 1), marine; 5, Caltianasso, a ghost shrimp (x '2), marine; 6, Astacus, a crayfish (x ' o), 

 fresh water; 7, Ponuiirui, o spiny lobster (to about 2 feet long), marine; Homarus, the Atlantic lobster 

 has larger pincers and resembles a crayfish, (Mostly redrawn from Schmitt.) 



same general structure; abdomen bent ventrally be- 

 tween third and fourth segments; mostly marine and 

 some along the shore; also fresh-water (Figure 14.13). 

 Amphipods, sometimes called scuds or sideswim- 

 mers, bear a superficial resemblance to isopods; how- 

 ever, a good many can be identified because they are 



flattened laterally. However, the differences in leg 

 and abdominal structures are a better basis for sepa- 

 rating the two groups. Like free-living isopods, scuds 

 carry their eggs in brood pouches under the abdomen 

 until the larvae hatch. 



Scuds are known for their voracious appetites. 



