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Leucothea japonica Komai (Ctenophora; Tentaculata; Lobata) Title spurts 'ink' when poked

Author(s) Kubota, Shin

Bulletin of the Plankton Society of Japan = 日本プランクトン Citation 学会報 (1996), 43(1): 45-46

Issue Date 1996-02

URL http://hdl.handle.net/2433/204537

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Type Article

Textversion publisher

Kyoto University 短 報 (Notes)

Bull. Plankton Soc. Japan, 43 (1): 45-46, 1996

Leucothea japonica Komai (Ctenophora; Tentaculata; Lobata) spurts `ink'when pokedl, 2

A lobate ctenophore Leuchothea japonica quired between ejections. However, where Komai, 1918 (Family Leucotheidae), having a this mk substance is stocked and how it is very fragile gelatinous body, was observed to ejected is yet to be clarified. spurt`ink when it was poked gently with the Similar observations on a lobate cteno- fingers. This is the second ctenophore species phore Eurhamphaea vexilligera Gegenbaur, showing this kind of behaviour as is most 1856 (Family Eurhamphaeidae) have previ- commonly found in cephalopods and opistho- ously been made by Mayer (1912) from Flor- branchs. ida, USA and Taniguchi (1975) from the sea An in situ observation was made on a sin- near Enoshima Island, Kanagawa Prefecture gle specimen of Leuchothea japonica at on the Pacific coast of mid-Japan. Tamguchi Sesoko Island, Okinawa Prefecture, southern (1975) also reported that the ejected sub- Japan on November 4, 1992. A moderate size stance killed the animal itself in a very short specimen was floating just below the sea sur- time in the laboratory and that the solution face on the west coast of this island. When which looks like a tincture of iodme was biト poked very gently with the fingers, it imme- ter in taste. This ink, excreted from numer- diately ejected a solution like a tincture of io- ous pores along the courses of the meridional dme, which formed a kind of cloud in the canals, is supposed to fulfill a protective func- seawater surrounding the animal. This `ink' tion as suggested by Mayer (1912) and was soon diluted by a weak current. When Taniguchi (1975), but what organisms this poked again it spurted ink as before. The ob- substance effects is unknown. servation was stopped at this moment to col- According to my observations none of lect some hydromedusae and a small, young three other species of ctenophores such as ctenophore with tentacles floating near the Beroe cucumis Fabricius (Atentaculata, animal. On a previous occasion ejection of Beroida), Coeloplana willeyi Abbott (Tentac-

一ink was not observed when a large specimen ulata, Platictenida), and Bolinopsis mikado of the same species was gently touched with Moser (Tentaculata, Lobata) have ejected the fingers. This specimen was part of a ink. Similar examinations on many other plankton assemblage including many ctenophore species are required to illuminate hydromedusae of different orders and a the extent of the above-mentioned beha- ctenophore Cestum amphitrites Mertens vioural trait and its significance to these two (Tentaculata, Cestida), and was floating just lobate species. below the sea surface along the coast of Honmura, Kuchinoerabu Island, Kagoshima Acknowledgments Prefecture, southern Japan on May 10, 1991. All the ink substance might have already Hearty thanks are due to Dr. Takashi been spent at the time that this specimen was Tokioka for his warmth and valuable sugges- examined, and probably some time is re- tions. Many thanks are due to the staff of the

Received: 8 December 1995/Accepted: 27 December 1995 2ツノクラゲ(有機動物門.,有触手綱.,カブトクラゲEj)つつくと"墨"放出 46 日本プランクトン学会報 第43巻 第1号(1996)

Sesoko Marine Science Center, the Univer- Mayer, A. G., 1912. Ctenophores of the Atlan- sity of the Ryukyus, for their kindness in pro- tic coast of North America. Carnegie In- viding me with facilities. I also wish to stitution of Washington, Washington, 58 express my heartfelt thanks to Dr. Susumu pp・ Ohtsuka and the crew members of the Taniguchi, T., 1975. Droplets from the plank- Toyoshio Maru, Hiroshima University, for ton net XXVI. Notes on the excretion in their kind help in my field observations at Eurhamphaea vexilligera Gegenbaur Kuchinoerabu Island. (Ctenophora). Publ. Seto mar. biol. Lab., 22: 321.

Literature Cited Shin Kubota Seto Marine Biological Laboratory, Faculty of Komai, T., 1918. 0n ctenophores of the Science, Kyoto University, Shirahama, Nishi- neighbourhood of Misaki. Annot. Zool. muro, Wakayama 649-21 Japon., 9: 451-474, 1 pi. 久保田信,京都大学理学部附属瀬テー1臨海実験所