EGGS OF PALAEMON MACRODACTYLUS: I. ATTACHMENT TO THE PLEOPODS AND FORMATION OF THE OUTER INVESTMENT COAT

¹ Aquaculture Program, Animal Science Department, University of California, Davis, CA 95616

Eggs of the estuarine shrimp, Palaemon macrodactylus, were examined for their method of attachment during the brooding period. They were attached to each other and to setae of the maternal pleopods by an externally applied outer investment coat that is believed to originate within the pleopods. A precursor substance was stored in packets extending longitudinally along the basipodites of the female pleopods, apparently originating in specialized epithelial cells continuous with the packets. At ecdysis prior to oviposition, the packets became depleted and the attachment or adhesive material became evident externally, conforming to the external surfaces of the pleopods. This occurred in the presence and absence of mature eggs in the ovary. If mature eggs were present, they were soon (within one-half day) extruded into the incubation chamber, coated with the adhesive material, and attached. Both fertilized and unfertilized eggs attached in the same manner, although unfertilized eggs were either shed or removed by the female within a few days. Eggs from pleopod-excised females did not attach, had no outer investment coat, and deteriorated rapidly. This attachment mechanism differs from those described for other decapods.

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