ABSTRACT
The classification of crustaceans parasitic on fishes is proposed below (based on Martin and Davis, 2001), Only the higher taxa accommodating parasitic species are shown. Subphylum Crustacea Brünnich, 1772
COPEPODA
Introduction
The subclass Copepoda is highly diversified ecologically. Humes (1994) estimated that there are 11,500 known copepod species. Copepods are commonly associated with microscopic components of marine-and freshwater zooplankton, but Boxshall (2005a) estimates that about half of
structure of an adult male are usually similar to those of the last larval stage. Such a male is often referred to as 'dwarf, which is not true because the absolute dimensions do not decrease but slightly increase. The impression of alleged dwarfism is caused by very extensive growth of a post-moult female, and the attained difference in size makes a false impression that the males actually decrease their size. The occurrence of male 'dwarfism' among different higher taxa is not consistent with their: evolutionary advancement, overall morphological adaptations, taxonomic position, or life cycle pattern, although it is more likely for a highly metamorphosed copepod to have 'dwarf males (Figs. 18.6, 18.17, 18.25). Extensive sexual dimorphism is equally characteristic for poecilostomes (e.g., Chondracanthidae; Fig. 18.6) and siphonostomes (e.g., Sphyriidae; Fig. 18.24, 18.25). Two different families of the same order of Siphonostomatoida (Caligidae and Pennellidae) show an extremely different approach to the relative size and structure of both sexes. Males representing the family Caligidae are almost equal in size to their female counterparts and their structure is almost identical, except for the size of the genital complex and some other minor details (Figs. 18.10-18.13, 18.43, 18.44). What is more important, caligid males are also parasitic and are capable of an independent life on the host.
