北太平洋亜寒帯域のカラヌス目カイアシ類に体表付着する繊毛虫吸管虫亜綱について

• Main Author: 山口, 篤
• Format: Article in Journal/Newspaper
• Language: Japanese
• Published: 日本プランクトン学会
• Subjects: Parasite; Host; Suctoria; Calanoid copepods; Metridia pacifica; 483; Okhotsk; Oyashio; Pacific; okhotsk sea; Subarctic; Copepods
• Online Access: http://hdl.handle.net/2115/52374

From zooplankton samples collected from subarctic Pacific and adjacent seas (Japan Sea and Okhotsk Sea), 10 calanoid copepod species including Gaetanus armiger, G. simplex, G. variabilis, Heterorhabdus tanneri, Heterostylites major, Metridia pacifica, Paraeuchaeta birostrata, P. elongata, P. rubra and Scaphocalanus magnus were found to host epibiont suctorian ciliates. Suctorian ciliates were observed on 5 developmental stages (C4M, C5F/M, C6F/M) among the copepodid stages. Seasonal observations on the prevalence of suctorians on M. pacifica in the Oyashio region western subarctic Pacific showed high incidence in summer to autumn when ambient temperatures were high. Within the subarctic Pacific, the prevalence of suctorians on M. pacifica was found to be higher at the high latitude stations. Suctorian ciliates on M. pacifica were classified into two types; type A characterized by short stalk and spherical cell (diameter: 50-100 μm), and type B, by enlarged stalk and petaloid-form tentacles (cell diameter: 300-500 μm). With regard to the substrate of suctorians on M. pacifica, they were observed most frequently on the urosome (89%), followed by the metasome (60%), cephalosome (19%) and swimming legs (5%), while they were never observed on the antennules, feeding appendages or caudal rami.