FISHERY BULLETIN: VOL. 77, NO 1 



none of Brooks' larvae metamorphosed into post- 

 larvae, he could not be sure of their identity. How- 

 ever, of the thousands he collected, all appeared to 

 Brooks to be "specifically identical" and the series 

 of forms were so complete with the differences 

 between the successive stages so slight that he 

 concluded there was "no reason to doubt that they 

 are all of the same species, and that species the 

 only one which is known to occur in the 

 Chesapeake Bay." However, we now know that 

 early larval stages of at least one other species of 

 stomatopod occur at the mouth of Chesapeake Bay 

 (Provenzano and Goy, pers. obs.) Brooks' descrip- 

 tion is inadequate to permit stages to be 

 adequately assigned to larvae. 



Brooks apparently was unable to obtain success- 

 ful molting in his larvae, but instead had to rely on 

 reconstruction to describe the larval history. He 

 provided no conjecture as to the number of pelagic 

 stages, and only partially described four stages. 

 Furthermore, the illustrations which Brooks in- 

 cluded were of whole specimens only; detailed 

 figures of appendages, necessary for accurate 

 species identification, were not made. 



Faxon (1882), working in Rhode Island, held 

 what he considered to be the last pelagic stage of S. 

 empusa until it metamorphosed and could be iden- 

 tified. However, the last stage larva and postlarva 

 appear to belong to another species, notS. empusa 

 (see Discussion). 



In this paper we describe the pelagic larval de- 

 velopment and postlarval stage of S. empusa. Be- 

 cause egg masses were not collected, hatched, and 

 reared, the propelagic stages remain undescribed. 

 Furthermore, because larvae were obtained from 

 the plankton, we are not positive that the larvae 

 described as stage I are the true first pelagic stage. 

 However, of the hundreds of larvae collected these 

 stage I larvae are the least developed and closely 

 resemble stage I larvae of other species reared 

 from eggs. 



A brief review of previous efforts to associate 

 stomatopod larvae with adults and a discussion of 

 possible specific and generic larval characters 

 within the Squillidae is presented. 



METHODS 



Larval specimens of S. empusa were collected 

 weekly 1 to 2 km north of Cape Henry at the mouth 

 of the Chesapeake Bay where we have determined 

 that a population of adults exists. A Vz-m plankton 

 net ( 153-/xm mesh) was used to make 10-min 



stepped oblique tows, as the ship circled the collec- 

 tion site at idle speed. 



Each plankton sample was placed into one or 

 two 1.9-1 (Va-gal) jars filled with sea water until 

 stomatopod larvae could be separated from the 

 sample. Separation of larvae from the samples was 

 started aboard ship and completed in the labora- 

 tory. Larvae were sorted according to size to 

 minimize cannibalism, and held temporarily in 

 aerated 1.9-1 jars filled with seawater. 



The larvae were then placed in compartmen- 

 talized plastic trays, one per compartment. Each 

 tray contained 18 compartments measuring 4.5 x 

 5x4 cm. Medium for rearing the larvae was made 

 from Instant Ocean Synthetic Sea Salts^ (Aqua- 

 rium Systems, Inc., Eastlake,Ohio) and tapwater. 



Larvae were reared over a range of tempera- 

 tures ( 10° to 25°C ) and salinities ( 10 to 35%o) in an 

 attempt to insure survival of at least some larvae 

 since optimum conditions were unknown. Because 

 the larvae were not hatched in the laboratory 

 under the temperature-salinity combination at 

 which they were reared, some larvae had to be 

 acclimated to the test conditions. Lavae were 

 never acclimated to temperature changes of more 

 than 5°C and 10%o/day. The larvae were main- 

 tained in total darkness except for brief periods ( 15 

 to 20 min/day) when they were examined and 

 transferred to newly prepared trays. 



Each larva was reared in 25 ml of water and 

 given approximately 30 Artemia salina nauplii/ml 

 daily. Decapod larvae and A. salina, grown on 

 yeast or an algal culture ofDunaliella, were fed to 

 larvae that became too large to capture or obtain 

 substantial nutrition from the A. salina nauplii. 

 Larvae were transferred daily, early stages by 

 means of a pipette, later stages with a spoon, into 

 compartments containing freshly prepared sea- 

 water and food. During this transfer, frequency of 

 molting, duration of larval development, survival, 

 and the stage of development were recorded. Dead 

 larvae were preserved in 709c ethyl alcohol and 

 10% glycerin. Preserved larvae were heated in a 

 59c potassium hydroxide solution to dissolve the 

 tissue so that only the exoskeleton remained. The 

 larvae were then stained in acid fuchsin red to 

 facilitate description and illustration. Larvae and 

 exuviae were dissected in lactic acid. All larval 

 appendages were illustrated using a Tasco camera 

 lucida on a Unitron binocular compound scope, 



^Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



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