The Larval Development of Eurypanopeus Depressus (Smith) Under Laboratory Conditions 1)

Abstract

The larval development of Eurypanopeus depressus (Smith) has been followed in the laboratory from hatching to the first stage crab and beyond. Approximately 1200 larvae were maintained on Artemia nauplii and fertilized Arbacia eggs at four salinities (12.5, 20.1, 26.7, and 31.1 p.p.t.) and three temperatures (20° C., 25° C., and 30° C.). From these studies the following conclusions may be made: 1. There are four zoeal stages and one megalopa stage in the complete development to the first crab stage. These are figured and described. 2. The setation of all functional appendages has been described and figured for each larval stage. There is a progressive increase in setation of the endites of the maxillule as development progresses. Setation of these appendages may serve to distinguish the zoeae of E. depressus from zoeae of P. herbstii. In living zoeae, the presence of chromatophores in the antennules of E. depressus may also be used to differentiate the zoeae from those of P. herbstii. 3. Although the megalopa of E. depressus may be distinguished from the megalopa of P. herbstii, differentiation of larval stages of Neopanope texana sayi, E. depressus, and P. herbstii will require a more complete description of the larvae of N. texana sayi.