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Larvae Information Summary for  Alosa mediocris
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Main Ref: Jones, P.W., F.D. Martin and J.D. Hardy Jr. 1978
Yolk-sac larvae
  max min mod Ref.
Length at birth (mm) 6.5 5.2 6.1 4639
Preanal L. % TL 86 80    
Place of development  
Larval area Mid-Atlantic Bight (Delaware Bay)
Yolk-sac       Ref:  
Yolk segmented Oil globules  
Rows on tail ventral row
Other melanophores on tail no other melanophores
Melanophores on head + trunk melanophores on trunk
Yolk is large, restricted to 1/4 of body and characterized by granular appearance. Eye large, unpigmented at hatching; hyomandibular, Meckel's cartilage, auditory vesicles present. Mouth open, but lacking esophageal connection; cleithrum and gill clefts formed or forming by 2nd day. Pectoral buds prominent at hatching; leaf-like at 1 day (Ref. 38619). Pigmentation: Initially limited to few chromatophores along gut. 1st day: abdomen with small melanophores; 18-20 elongate melanophores along ventral surface of gut between yolk and anus; few dots on dorsal surface; eye darkly pigmented. 3rd day: single line of 18-25 melanophores on upper surface of intestine, bifurcating at yolk and extending to region below origin of pectoral fin; few melanophores posterior to anus and on caudal finfold.
Post larvae
Striking feature none
Striking shape lateral normal (not striking) dorsal  
Striking feature none
Shape of gut tube-like
Gas bladder   early   late  
Spinal armature   early no spines late no spines
Pigmentation early
Rows on tail ventral row
Other melanophores on tail tail partly covered with melanophores
Melanophores on head + trunk melanophores on trunk
Rows on tail ventral row
Other melanophores on tail tail partly covered with melanophores
Melanophores on head + trunk melanophores on trunk
Pectorals normal  
Pelvics normal (i.e. small or absent)  
Size range: 6.5-18.0 mm TL. Average preanal myomeres 39 at 6.5-7.0 mm, 38 by end of stage. Body is elongated; anus 4/5 TL from head. Pigmentation: Initially as in yolk-sac larvae; by end of stage, melanophores on ventral part of body from gular region to area above anal fin. Sequence of fin formation: dorsal (9.0 mm), anal (14.0 mm), pelvics (13.0 mm).
  L 1st feeding Ref. Months of presence of larvae
max     Jan Feb Mar Apr
min   May Jun Jul Aug
mod     Sep Oct Nov Dec
Water parameters     Metric characters
Entered by: Luna,Susan M. - 31.05.01
Modified by: Luna,Susan M. - 29.01.02
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