Aspects of the life-cycle of the Antarctic fish parasiteGnathia calvaVanhöffen (Crustacea: Isopoda)

摘要

The life-cycle of the Antarctic fish parasiteGnathia calvaVanhöffen, 1914 (Crustacea, Isopoda) is described. Three larval instars (pranizae) were discerned. Each instar sucks blood from benthic fishes once and then rests hidden for a period of up to 2 years. Pranizae, that have fed, have swollen pereonites, they bear symbiotic bacteria in a rectal vesicle. The third instar is frequently found within small hexactinellid sponges, where they moult and metamorphose into mature specimens. Within the sponges usually a single male is found together with several females and immature adults. On occasions, a premale moults into a second male and an intraspecific fight eliminates one of the males. Adult stages do not feed