Marine Planktonic Copepods

General Features of the External Morphology of Marine Planktonic Copepods

1. Introduction 2. General morphology 3. Morphology of the various body parts and appendages 4. Dimensions 5. Body forms 6. Principal structural modifications 7. The antennules 8. The antennae 9. The buccal frame 10. The Mandibles 11. The Maxillules 12. The Maxillae 13. The Maxillipeds 14. The swimming legs 15. Variation in segment number 16. Nomenclature and Metamerism 17. Tegumental structures and organs 18. Visual organs 19. Morphological variations 20. Sex-ratio 21. Gynandromorphism and intersexuality 22. Mating 23. Parthenogenesis 24. Characteristics of egg-laying 25. Larval forms 26. Duration of development 27. Growth 28. Regeneration 29. Anomalies 30. Classification and Phylogeny 31. References 32. Photo library

Parthenogenesis

Some cases of parthenogenesis were formerly reported in Harpacticoida. Roy (1931), studying the freshwater harpacticoid Elaphoidella bidens, was able to obtain from a single egg five successive generations without males. Sarvala (1979) confirms this mode of reproduction in a lacustrine population of Canthocamptus staphylinus, which is otherwise bisexual.

It seems possible that parthenogenesis also exists in certain bathypelagic calanoids, as in the family Scolecitrichidae (M+F = 78; females alone known: 88; males alone known: 18), in which males are rare and in which no spermatophore is reported on females. However, the study of the sex ratio in pelagic copepods does not appear to support this reproductive mechanism, which remains yet to be demonstrated.

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