The total number of marine and brackish planktonic species of copepods
is evaluated at about 1950, belonging to 9 of the 10 sub-classes of C
opepoda. Only the Gellelyoida, which are fresh-water and underground f
orms are not considered. These species are distributed over 59 familie
s and 253 genera. According to the genera number distribution in famil
ies, 2 families yield the largest generic radiation: the Aetideidae an
d the Scolecitrichidae, with a dominance of mesopelagic and bathypelag
ic species. 63% of families have a restricted number of genera (1 to 3
), some belonging to orders having their full expansion in the benthos
. The families with epipelagic forms and those with herbivorous and om
nivorous characters are weakly diversified in contrast to carnivorous
forms. Sex-ratio analyses based on the number of individuals in sample
s indicate a strong dominance of females; one has to take into account
, however, that both males and females are described for 67% of the to
tal number of species, 28% is exclusively based on females and 5% on m
ales.