FISHERY BULLETIN: VOL. 69, NO. 2 



opening of 



eiopod 



Figure 6. — Ventral view of thorax of adult female with 

 spermatophore (shaded) attached. 



upright position. If frightened, they flip back 

 in typical penaeid fashion by quick flexing of 

 the abdomen and then swim forward rapidly, 

 but usually they are turned on their sides so 

 that they bounce off the bottom every few feet. 

 At the end of the run they stand on the bottom 

 rather than burrow in. The shrimp walk either 

 forward or sideways. Color varied from grayish 

 pink to red — similar to colors observed on trawl- 

 caught specimens." 



LARVAL, POSTLARVAL, AND JUVENILE 

 STAGES 



The larvae of Hymenopenaetcs robustus are 

 unknown. Several attempts were made by An- 

 derson to hatch eggs from ripe females bear- 

 ing spermatophores. The eggs failed to devel- 

 op, however — perhaps because of the drastic 

 changes in temperature and pressure when the 

 animals were quickly brought from the cold 



5 mm 



FiGLiRE 7. — Ventral view of detached spermatophore. 



waters of about 385 m (200 fm) to the warm 

 surface waters of the Gulf Stream. 



In attempts to find larval and postlarval royal 

 red shrimp, we examined numerous plankton 

 samples from the M/V Theodore N. Gill cruises, 

 covering all seasons, in an area from about the 

 183-m (100 fm) contour to well beyond the axis 

 of the Gulf Stream and over the entire length 

 of the St. Augustine Grounds. Only a few larval 

 or postlarval penaeids were found and only one 

 of these, a Sole7wcera-\ike mysis stage, was con- 

 sidered as possibly being Hymenopenaeiis (Har- 

 ry L. Cook, then a fishery biologist at the BCF 

 Biological Laboratory. Galveston, Tex., kindly 

 made the identifications). 



Burkenroad (1936) has provided the only rec- 

 ord of postlarval H. robtistus. He described nine 

 specimens (all dead when examined), which he 

 believed to be juveniles (postlarvae), that were 

 collected in the northern Gulf of Mexico off the 

 mouth of the Mississippi River. Eight (12.0- 

 21.5 mm total length) were taken at R/V At- 

 lantis station 2377 on March 24, 1935, and one 

 (no length given) was taken at Atlantis station 

 2381 on March 26. 1935. 



318 



