200 MARINE FISHERIES OF NORTH CAROLINA 



The occurrence of P. brasiliensis in this country is probably very rare. 



MIGRATORY MOVEMENTS 



As has been shown, there is a general offshore movement of shrimp coin- 

 cident with maturity. The spring run of "lobster shrimp" in Louisiana is 

 interpreted by Burkenroad as a shoreward migration of individuals that 

 have spent the winter in deeper waters. 



It is of especial interest to determine the mechanics of the migration of 

 planktonic larvae from the deep-water spawning grounds to the inlets and 

 estuaries where they enter the inside waters. Since the larvae are plank- 

 tonic, this migration must be made possible through shoreward-moving cur- 

 rents. Bumpus and Wehe (1949) have postulated a series of such currents 

 from Cape Hatteras to the Florida Capes on the results of recent hydro- 

 graphic studies. 



Higgins (1937, '38, '39, '40) has reported coastwise migration of white 

 shrimp in the western Atlantic. Shrimp tagged at the northern extremities 

 of the geographic limit of abundance have been recovered farther south, indi- 

 viduals sometimes being recovered as far as 200 miles from the place of 

 tagging. A southward migration during fall and winter is followed by a 

 northern migration in the spring. This migration is recorded as extending 

 from North Carolina to Florida. Burkenroad's (1939) mention of the 

 appearance of P. aztecus off the coast of New Jersey in early fall suggests a 

 similar migration for this species. 



HABITS 



No systematic examination of stomach contents has been reported. The 

 shrimp is, however, according to Weymouth, Lindner, and Anderson (1933) 

 a "voracious and well-nigh omnivorous feeder." They list worms, Crustacea 

 (not excluding shrimp of the same species), small mollusks and plant debris 

 as items in the diet of adult shrimp. Considerable amounts of mud and sand 

 are usually present in the intestine, and it seems not unreasonable to assume 

 utilization of contained organic matter. In aquaria, shrimp have been ob- 

 served to attack and devour small fish and other shrimp of the same species 

 (Weymouth, Lindner, and Anderson, 1933) and to feed upon beef liver 

 and oyster meats. 



Shrimp move about in three ways. The periopods, or walking legs, are used 

 in walking about on the bottom. In swimming, the walking legs are flexed 

 under the cephalothorax, or "head," and the animal is propelled through the 

 water by rhythmic beating of the pleopods, or swimming legs. When the 

 shrimp is alarmed, the abdomen is flexed rapidly, the uropods and telson, or 

 fantail, serving as a fin to propel the animal backward through the water. 

 Several repeated backward flips may carry the animal a distance of thirty 



