著者

NAOHIKO WATANUKI GUNZO KAWAMURA SHOHEI KANEUCHI TORU IWASHITA

出版者

The Japanese Society of Fisheries Science

雑誌

Fisheries science (ISSN:09199268)

巻号頁・発行日

vol.66, no.3, pp.417-423, 2000 (Released:2009-03-31)

参考文献数

21

被引用文献数

21

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The role of vision in the entry of the cuttlefish Sepia esculenta into basket traps was examined in laboratory experiments and by histological examination of the retina. Both entry into the trap and feeding on shore crabs stopped when the tank was completely darkened. The eyes of cuttlefish have a high sensitivity to light. The visual field of cuttlefish was determined by the optical method, based on the assumption that incident light on the pupil from any direction reaches the retina through a refractive lens. The uniocular visual field was found to be 253° on the horizontal plane, and the anterior and posterior binocular visual fields were 86° and 60° respectively. On the retina, areas with especially high visual cell density formed a visual equator slightly above the optical equator. The distribution of the visual cell density indicates no specific visual axis. The visual acuity is 0.36 when estimated from the bait recognition distance and the size of bait during feeding, and 0.89 when determined from the visual cell density at the visual equator and the focal length of the lens. Cuttlefish have far superior visual acuity than fish.

著者

小倉 芳子 松岡 達郎 川村 軍蔵 川村 軍蔵 Yoshiko Ogura Tatsuro Matsuoka Gunzo Kawamura 鹿児島大学大学院連合農学研究科 鹿児島大学水産学部 鹿児島大学水産学部 鹿児島大学水産学部 The United Graduate School of Agricultural Sciences Kagoshima University:(Permanent address) Faculty of Fisheries Bogor Agricultural University (IPB) Faculty of Fisheries Kagoshima University Faculty of Fisheries Kagoshima University Faculty of Fisheries Kagoshima University

出版者

The Japanese Society of Fisheries Science

雑誌

日本水産学会誌 = Bulletin of the Japanese Society of Scientific Fisheries (ISSN:00215392)

巻号頁・発行日

vol.65, no.6, pp.991-997, 1999-11-15

参考文献数

13

被引用文献数

2 2

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触刺激に対するζポイント, ζ_tが網地に遭遇した魚の前進行動の継続に与える影響を調べるため, 失明させたコイ, ニジマス, ティラピア, ブルーギルを用いた水槽実験を行った。供試種では, 魚体の長さ方向での接触位置により前進後退行動が入れ替わり, ζ_tポイントの存在を確認できた。ζ_tポイントの位置は種固有で種間で異なる。網地に遭遇した魚の前進継続率は, 目合い, 縮結によって異なり, ζ_tポイントに基づく前進後退行動の分岐モデルに基づいて計算した前進継続確率でよく説明できた。刺網の漁獲過程で網地に遭遇した魚が網目に進入する確率は, ζ_tポイントの位置, 魚体の大きさと形状, 目合いと縮結に影響されると結論した。Two series of glass-tank experiments with blinded fish were conducted to investigate the existence of a ζ-point (a body section over which external stimulation alters forward and back ward motions of fish) against tactile stimulation and its effect in determining the direction of swimming upon contact with a net webbing. Cyprinus carpio, Salmo mykiss, Tilapia mossambica and Lepomis macrochirus were tested. Longitudinally random positions over the bodies of these fish were stimulated using thin sticks and they moved either forward or backward according to the location of the stimulated positions. Cyprinus carpio which encountered net webbing expanded in a tank proceeded into a mesh at different ratios under the conditions of three mesh sizes and three hang-in ratios. Geometrical analysis of contact of a netting twine and a fish body section indicated that the probability of proceeding into an encountered mesh increases with mesh size and is modally maximised at a certain hang-in ratio. It was concluded that, (1) a tactile ζ-point, ζ_t exists at a body section which is unique to each species, and (2) the probability for fish to proceed into a mesh of gillnet is affected by the position of ζ_t, body form and size, mesh size and hang-in ratio.