FORAMINIFERAN (PROTOZOA) EPIZOITES ON ARCTIC ISOPODS (CRUSTACEA) AS INDICATORS OF ISOPOD BEHAVIOR

A total of 38219 specimens representing 63 species of marine isopods ( Crustacea) from deep and shallow Arctic waters were studied in a searc h for epizoic foraminifers (Protozoa). Foraminifers occurred on 21 spe cies, and their frequency was generally low. A total of 290 foraminife r individuals were found, of which 289 belonged to Cibicides wuellerst orfi, C. refulgens and Cibicides spp. (juveniles) (Cibicidae), while o nly a single individual belonged to Cornuspira sp. (Cornuspiridae). Th e foraminifers were most frequent on species of the families Munnidae, Ischnomesidae (suborder Asellota) and on Gnathia stygia (suborder Gna thiidea), but were totally absent from the asellote families Janiridae , Haploni-scidae, Nannoniscidae and from the suborder Epicaridea. The foraminifers were mainly located on the legs (Munna acanthifera), the anterior part of the body (Haplomesus quadrispinosus, Heteromesus frig idus), or on the head (G. stygia adults). The epizoic foraminifers occ ur mainly on epibenthic isopods, which do not or only rarely clean the mselves. The foraminifers are known to prefer elevated substrata, and in this the habitat of the isopods and the foraminifers coincide. The size of individual isopods was not related to the presence or absence of foraminifers.