Der Fortpflanzungszyklus vonCyathura carinata (Isopoda, Anthuridea) im Nord-Ostsee-Kanal

Abstract

The life cycle ofC. carinata (Krøyer) from the Kiel Canal and the seasonal change of its population structure have been studied.C. carinata is a protogynic hermaphrodite which may attain an age of 3 years. The young are born in summer and only very few reach sexual maturity during the following year. Some of them become functional small males without passing through a female stage. At the end of the breeding season, some individuals of the same generation become functional females. They moult into pre-males during winter and are functional males in the following summer, when they are 2 years old. The remaining two-year-old animals are breeding females. Mature females can be recognized by the presence of antennules with four jointed flagella and 3 pairs of oostegites. In September they moult to pre-males which have antennules equipped with six jointed flagella. In June of the following (third) year they become functional males which die at the end of the breeding season. It is supposed that this cycle also applies for population from the Gdansk Gulf studied by Jażdżewski (1969) despite a different interpretation given by this author.