FISHERY BULLETIN: VOL. 73, NO. 1 



Table 1.— The area, station number, and position of samples 

 from which larvae of £. gibboides were obtained. 



and Fleminger ( 1965) and in University of Cali- 

 fornia Data Reports (Scripps Institution of 

 Oceanography 1964a, b). 



The larvae were grouped by developmental 

 phase, measured, and dissected for detailed study 

 of appendages. The identification of eggs, nauplii, 

 and metanauplius is based on their relative 

 abundance in samples in which calyptopes and 

 furcilia of E. gibboides were clearly the domi- 

 nant euphausiid larvae. Identification of calyp- 

 topis and furciUa stages, based on morphology, 

 distribution, and relative abundance with juve- 

 niles and adults of .E. gibboides, was substan- 

 tiated by the study of a series of juvenile forms 

 the largest of which had characters of both the 

 furcilia phase and the adult. 



The identification of calyptopis I was confirmed 

 by rearing after the manuscript had been accepted 

 for publication. A gravid female of £^. gibboides, 

 caught in a mid-water trawl collection at lat. 

 27°35.5'N, long. 115°52.0'W, deposited her eggs 

 soon after capture and larvae which hatched 

 from the eggs were cultured through the first 

 four developmental stages. I am indebted to 

 Edward Brinton and Annie Townsend who under- 

 took the rearing study of E. gibboides aboard 

 RV Alexander Agassiz during Leg I of Scripps 

 Institution of Oceanography Expedition Krill, 

 May-June 1974. 



Reviews of the literature dealing with the 

 larval development of the Euphausiacea and 

 discussions of their larval phases are given by 

 Mauchline and Fisher { 1969) and Gopalakrishnan 

 (1973). The nomenclature used in the descrip- 

 tion of £. gibboides is modified from Sars (1885) 

 as follows. 



Nauplius phase (two stages): Body oval, 

 unsegmented, without compound eyes; 3 pairs 



of limbs present, antennulae uniramous, 

 antennae and mandibles biramous and 

 natatory. 



Metanauplius phase (one stage): Body unseg- 

 mented, with carapace; only 2 pairs of limbs 

 present (antennulae and antennae); mandi- 

 bles, maxillules, maxillae, and maxillipeds 

 (first thoracic legs) present as bud-like 

 prominences. 



Calyptopis phase (three stages): Body divided 

 into two principal sections; abdomen becomes 

 segmented; thoracic segments develop but 

 are much compressed; compound eyes im- 

 perfectly developed, immobile and covered 

 by hood-like expansion of carapace; man- 

 dibles, maxillae, and maxillipeds distinct 

 and functional; thoracic legs posterior to 

 first leg and pleopods not present; uropods 

 develop. 



Furcilia phase (variable number of stages): 

 Compound eyes more fully developed, mobile, 

 and projecting beyond sides of carapace; 

 antennae at first retaining original natatory 

 structure, later transformed to adult form 

 wdth scale and developing flagellum; legs 

 and pleopods develop; method of locomotion 

 thus changes as setose pleopods replace modi- 

 fied antennae for swimming; photophores 

 develop; terminal telson spines become 

 reduced in number, last furcilia stage with 

 1 terminal telson spine and 3 posterolateral 

 spines. 



Juvenile phase: Begins when telson has 2 

 posterolateral and 1 terminal telson spines, 

 the adult number. 



Individuals were straightened on a glass slide 

 in a drop of preservative for measurement with 

 an ocular micrometer. Measurements of develop- 

 mental phases were as follows. 



Egg: Diameter of capsule and width of peri- 

 vitelline space measured only in specimens 

 with undeveloped embryos. 



Nauplius: Length between midpoints of anterior 

 and posterior margins; width at widest point. 



Metanauplius: Length between midpoints of 

 anterior margin of rostral hood and posterior 

 margin of abdomen; width of rostral hood 

 at widest point; width of body at widest 

 point posterior to rostral hood; measurements 

 exclude spinose fringe on rostral hood and 

 telson spines. 



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