Cibicides spp. (Protozoa, Foraminifera) as epizoites on the Arctic antenna-brooding Arcturus baffini (Crustacea, Isopoda, Valvifera)

Abstract

Cibicides spp. epizoites (Protozoa, Foraminifera) were studied on the arcturid Arcturus baffini (Crustacea, Isopoda, Valvifera), which carries its juveniles on the long second antenna. The pattern of forarminiferan epibiosis changed during ontogenetic development, and was different for adult females and males. The first two developmental (manca) stages carried foraminifers mainly on their bodies, while on the third manca stage the foraminifers became more frequent on the long second antenna. Settlement on the first two manca stages was mainly by fairly large, vagrant Cibicides refulgens probably arriving from the mother. The third manca stage individuals, however, gathered larvae mainly from the water column and these settled on the inner side of the long second antenna. Foraminifers were also most frequent on the long second antenna of the adults, which was probably most exposed to settling foraminifers. Adult females carried more foraminifers than males; brooding females had about 2.1 times more foraminifers on the second antenna than males of comparable size, but 3.7–4 times more foraminifers on their body and legs than the males. Foraminifers were somewhat larger on adult females than on adult males. This pattern may be related to somewhat longer time-spans available for settling on the females between moults. The different pattern of foraminiferan epibiosis between females and males may be due to migration of foraminifers from the females to juveniles carried on the second antenna.