LARVAL DEVELOPMENT OF THE SPIDER CRAB, 

 LIBINIA EMARGINATA (MAJIDAE) 1 



D. Michael Johns 2 and William H. Lang 3 



ABSTRACT 



Larval development of the spider crab, Libinia emarginata, consists of two zoeal stages and megalopa. 

 Laboratory-reared larvae (South Carolina and Rhode Island) are described and compared with 

 planktonic larvae from Narragansett Bay, R.I. No significant variations in morphology were found 

 between laboratory-cultured larvae and "wild" larvae from plankton catches; first stage zoea from 

 South Carolina were smaller than Rhode Island specimens. Using Artemia diets, the best percentage 

 survival in culture was found to be 20°C for Rhode Island larvae and 25°C for South Carolina larvae. 

 Zoeal stages show little difference from larvae of L. dubia; however, the megalopae of the two species 

 can be differentiated by the number of protuberances on the cardiac region of the carapace. 



Larval stages have previously been described for a 

 number of species from the family Majidae (San- 

 difer and Van Engel 1971, 1972). For the genus 

 Libinia only two complete descriptions have been 

 published. Boschi and Scelzo (1968) described lar- 

 val stages of L. spinosa from Mar del Plata Harbor, 

 Argentina; and Sandifer and Van Engel (1971) 

 described the larval stages of L. dubia from 

 Chesapeake Bay. Larvae of L. erinacea have been 

 described by Yang (1967), but the results remain 

 unpublished. In all cases, the larval development 

 consists of two zoeal stages and a megalopa. 



Adult Libinia emarginata Leach range from 

 Windsor, Nova Scotia, to the western Gulf of 

 Mexico and are found in nearshore waters down to 

 a depth of 29 m (Williams 1965). Although the 

 larvae of L. emarginata have not been formally 

 described, they have been successfully reared (J. 

 D. Costlow, pers. commun.). Grassle (1968) 

 studied heterogeneity of hemocyanins during on- 

 togeny, but no attempt was made to describe de- 

 velopment. In support of ongoing studies using 

 Libinia larvae at this laboratory, the present 

 study was undertaken to: 1) describe the larval 

 stages, 2) compare morphology of laboratory cul- 

 tured and field collected larvae, and 3) determine 

 successful temperature-salinity rearing parame- 



•Contribution No. 176 from the Belle W. Baruch Institute for 

 Marine Biology and Coastal Research. 



2 United States Environmental Protection Agency, Environ- 

 mental Research Laboratory, South Ferry Road, Narrangansett, 

 R.I. 20882. 



3 Belle W. Baruch Institute for Marine Biology and Coastal 

 Research, University of South Carolina, Columbia, SC 29208. 



ters and development times. Characteristics 

 which distinguish L. emarginata larvae from the 

 larvae of L. dubia and L. erinacea were also noted. 



METHODS AND MATERIALS 



Ovigerous females of L. emarginata were col- 

 lected off Charleston, S.C., during fall 1975 and 

 spring 1976, and in Narragansett Bay, R.I. , during 

 summer 1976. Females were isolated in chambers 

 at 25 °C (in South Carolina) or 20°-22°C (in Rhode 

 Island) and 30%o. After hatching, zoeae were iso- 

 lated into compartmentalized plastic boxes. Lar- 

 vae were fed day old Artemia every other day 

 following a change of water. Larvae reared at 

 salinities other than 30%o were brought to the 

 appropriate levels (15, 20, 40, or 45 %o) using in- 

 crement changes of 2.5%o every 30 min. Larvae 

 reared at temperatures other than hatching tem- 

 perature were brought to the test temperature 

 (15°, 20°, or 30°C) by placing larvae in environ- 

 mental chambers and allowing them to equili- 

 brate to these temperatures. 



Field samples were obtained from surface 

 plankton tows collected in Narragansett Bay dur- 

 ing July and August 1976. 



Drawings were made with the aid of camera 

 lucida using exuviae and larvae fixed in 10^ For- 

 malin. 4 Carapace and total lengths were made 

 with an ocular micrometer. Dry weights were de- 

 termined with a Cahn Electrobalance on larvae 



Manuscript accepted March 1977. 



FISHERY BULLETIN: VOL. 75, NO. 4, 1977. 



"•Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



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