FISHERY BULLETIN: VOL. 71, NO. I 



Table 1. — Location of samples collected by RV Stranger during EQUAPAC Expedition which contained larvae of 

 Thysanopoda tricuspidata and the developmental stages found. Detailed station data for samples are given by 

 Snyder and Fleminger (1965). 



2% formaldehyde in seawater on a slide. Total 

 length (TL) was measured in dorsal view be- 

 tween center of anterior margin of carapace 

 (excluding spines in metanauplius) or rostrum 

 and distal point on posterior margin of telson 

 excluding spines. Other measurements are ex- 

 plained by stage: nauplius II, width (W) at 

 widest point in dorsal view; metanauplius, car- 

 apace length (CL) between midpoints of anter- 

 ior and posterior margins excluding spines, car- 

 apace width (CW) at widest point between 

 anterolateral margins excluding spines, both 

 measured in dorsal view; calyptopes I and II, 

 carapace length (CL) between midpoints of an- 

 terior and posterior margins measured in lateral 

 view; calyptopis III, carapace length (CL) from 

 rostrum to distal point on posterior margin 

 measured in lateral view. The range (r) and 

 mean (m) of each measurement and number 

 (n) of specimens measured are given by stage. 

 Approximately equal numbers of the meta- 

 nauplius stage from the Indian and Pacific 

 Oceans were measured. The measurements 

 given for nauplius II and calyptopes I-III, how- 

 ever, are based only on larvae from the Equa- 

 torial Pacific and, as calyptopis larvae of a single 

 species have been shown to vary in size in dif- 

 ferent areas of the oceans (Mauchline and Fish- 

 er, 1969) , it should be emphasized that the larvae 

 measured for this study were collected during 

 one season in one area of the Pacific. Measure- 

 ments of some nauplius II and calyptopis stages 

 sorted from Indian Ocean samples did fall well 

 within the size ranges of Pacific larvae in equiv- 



alent developmental stages. Specimens of a 

 nauplius I definitely referable to T. tricuspidata 

 were not found. 



For detailed study and dissection of append- 

 ages, larvae were placed in glycerine. Some 

 were stained with Chlorazol Black E to clarify 

 appendage setation. Fourteen nauplii and at 

 least 20 individuals of each of the metanauplius 

 and calyptopis stages I-III were examined in 

 detail. At least 10 specimens of each stage 

 were dissected for study of appendages. In a 

 study of the larval development of Nematoscelis 

 difficilis based on both larvae reared in the lab- 

 oratory and larvae from the plankton, Gopala- 

 krishnan (in press) found no variability in form 

 or setation of appendages among individuals at 

 the same stage of development. This also ap- 

 pears to be true of T. tricuspidata larvae, in the 

 stages described, with respect to the mouthparts 

 where setation is usually intact in preserved 

 specimens. On antennules, however, the ter- 

 minal setae, spines, and aesthetascs (sensory set- 

 ae) were frequently broken; in calyptopis II, for 

 instance, only 1 of 26 antennules examined had 

 the third seta intact on the inner and outer fla- 

 gella. An estimate of variability in the fragile 

 setation in this species will require a detailed 

 study of larvae either reared in the laboratory or 

 collected specifically for the purpose. 



Drawings of both whole larvae and append- 

 ages were prepared with the Wild M20' com- 



' Reference to trade names does not imply endorse- 

 ment by the National Marine Fisheries Service, NOAA. 



54 



