The biology of Clavella uncinata (Muller) (Crustacea: Copepoda)

Abstract

Clavella uncinata (Muller) (Crustacea: copepoda) was found infesting 24% of 1352 whiting Odontogadus merlangus (L.) examined from the North Irish sea.A study of the dimensions of the adult female and a comparison of the morphology of copepodid larvae from the Clavella of whiting and pollack Pollachius pollachius (L.) suggests that the Clavella from these gadoids are all one species. Observations on the process of feeding and histochemical analysis of the gut contents indicate that the parasites feed by browsing on the superficial tissues of the whiting and that the mouthparts are used more for the gathering of food towards the mouth than for cutting. Observations show that the hatching of eggs and the behaviour of the nauplii are remarkably similar to these functions in free-living copepods. Examination of Clavella from adult and young whiting, and from living specimens kept alive on the fish, suggests that there are definite cycles of development, that the eggs take about 21 days to mature and that adult Clavella has a life span of no more than 6 months.I would like to thank the Masters and crews of the R.V. Cuma and R.V. Silver Spray and the staff of the Marine Biological Station, Port Erin for their help in the collection of material. I am especially grateful to Mr D. J. Slinn who guided me throughout this work and to Mr R. Moore for his technical assistance.