SPERMATOPHORE TRANSFER IN EUCHAETA SPECIES IN A 2000-M WATER COLUMN

The numbers and placement of spermatophores transferred by males to fe males in the genus Euchaeta are examined in the northeastern Atlantic Ocean. Multiple placement of spermatophores is present in the five die l, vertically migrating species, E. acuta, E. pseudotonsa, E. gracilis , E. norvegica and E. hanseni. Direct placement covering the genital o pening is usually, but not always the primary placement site. Males pr oduce two sizes of spermatophores corresponding to the small directly placed and the large indirectly placed ones attached to the females. F emales of the other species, E. barbata, E. barbata f. farrani, E. sco tti, E. bisinuata, E. sarsi, E. abbreviata, E. longissima and E. brady i, all meso- or bathypelagic non-vertically migrating species, have a single spermatophore attached to the genital opening. Spermatophore si ze is related to male and female prosome lengths and to the depth at w hich the species lives. Size variation of spermatophores within specie s decreases with increasing depth. Spermatophore transfer in deep-sea species, a single spermatophore directly placed, appears to be more ef ficient than in the epipelagic and mesopelagic vertical migrators wher e multiple placement involves a proportion of spermatophores with no d irect connection to the genital opening.