NOTES 



STAGE 1 ZOEAE OF A CRANGONID SHRIMP, 



CRANGON FRANCISCORVM ANGVSTIMANA, 



HATCHED FROM OVIGEROUS FEMALES 



COLLECTED IN KACHEMAK BAY, ALASKA 



Information on the larval stages of crangonid 

 shrimp of the North Pacific Ocean is meager. Need- 

 ier (1941) described the first zoeal stage of Cran- 

 gon septemspinosa (as Crago septemspinosus Say) 

 hatched in the laboratory from ovigerous females 

 and the remaining four zoeal stages from plankton 

 collected near Prince Edward Island, Canada. 

 Kurata (1964) described the larval stages of C. 

 affinis de Haan and various larval stages of six 

 unidentified Crangon spp. from Japanese waters. 

 He obtained the first zoeal stage of C. affinis from 

 known parentage, but the remaining stages were 

 collected from plankton. Makarov (1967) briefly 

 described larvae of C. dalli Rathbun and C. sep- 

 temspinosa (Say) which were collected from 

 plankton along the western Kamchatka shelf. He 

 suggested that C. dalli was an analog of C. 

 allmani Kinahan and C. septemspinosa was an 

 analog of C. crangon (Linnaeus). Crangon allmani 

 and C crangon are eastern Atlantic species. He 

 assumed that the C. affinis larvae described by 

 Kurata (1964) were actually larvae of C. sep- 

 temspinosa. Loveland ( 1968) described larvae of C 

 alaskensis Rathbun reared in the laboratory from 

 females collected near Anacortes, Wash. 



Morphology of Stage I larvae is closely related to 

 Caridean development and can be used to estimate 

 the number of larval stages, classify species, 

 categorize larvae for identification purposes, and 

 identify subsequent larval stages (Needier 1938; 

 Pike and Williamson 1961, 1964; Kurata 1964; 

 Ivanov 1971; and others). In this report I describe 

 and illustrate the first zoeal stage of C. francis- 

 corum angustimana Rathbun from ovigerous 

 females and compare these zoeae with Stage I 

 zoeae of crangonids described by other authors. 

 Also, I show that the criterion of the absence of 

 exopodites on the second pair of pereopods for dis- 

 tinguishing larvae of Crangon from other genera 

 of the Crangonidae is invalid for Crangonidae of 

 the North Pacific Ocean. 



Methods 



Ovigerous C. franciscorum angustimana were 

 caught at 30 m (16 fathoms) in shrimp pots in early 

 May 1976 in Kachemak Bay, Alaska. Four 

 females were kept in seawater in a plastic bucket 

 for about Vi h and then each female was put into a 4 

 1 glass jar containing filtered, aerated seawater. 

 The water was about 35%o salinity, about 6°C, and 

 was changed daily until zoeae were released, 

 about 5 days later. Most zoeae were released at 

 night. I did not determine whether the larvae were 

 hatched as prezoeae. 



Terms used in the text, nomenclature of gills 

 and appendages, and techniques of measurement 

 and illustration are given by Haynes ( 1976). As an 

 aid to the study of segmentation and setation, 

 some larvae were cleared in 10% KOH and the 

 exoskeleton stained with Turtox' CMC-S (acid 

 fuchsin stain mountant). Only the left number is 

 figured because the paired appendages of the lar- 

 vae are symmetrical; except, the mandibles are 

 drawn as a pair. There was no morphological vari- 

 ation, except variation in total length, among the 

 zoeae used for the description. 



Stage I Zoea 



Mean total length of Stage I zoeae (Figure lA) 

 was 3.1 mm (range 2.8-3.3 mm; 10 specimens). 

 Rostrum slender, spiniform, without teeth, about 

 one- third length of carapace. Carapace with small 

 rounded prominence near posterior margin. Two 

 distinct denticles immediately posterior to 

 pterygostomian spine; no supraorbital or antennal 

 spines. Eyes sessile. 



ANTENNULE (Figure IB).— First antenna, or 

 antennule, an unsegmented peduncle (inner 

 flagellum) bearing a conical projection and a 

 setulose spine. Conical projection bears a simple 

 seta and three aesthetascs of about equal length. 



ANTENNA (Figure IC).— Consists of inner 

 flagellum (endopodite) and outer antennal scale 

 (exopodite). Flagellum unsegmented, slightly 



' Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service. NOAA. 



FISHERY BULLETIN: VOL 77, NO 4. 1980. 



991 



