Rademacher, Katharina (1993) Angriffs- und Fluchtverhalten pelagischer Fische (Spinachia spinachia) und ihrer Beute (Neomysis integer). (Diploma thesis), Christian-Albrechts-Universität zu Kiel, Kiel, Germany, 48 pp.

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Abstract

Predatory behaviour of pelagic fish and escape responses of their prey were studied using the fifteen-spined stickleback (Spinachia spinachia) and the mysid Neomysis integer as example species of predator-prey interactions. Optical methods were applied to quantify the behaviour of the two species under laboratory conditions. At the beginning of each attack, S. spinachia approached N. integer to 0.66 cm. After a successful approach S. spinachia attacked its prey with a maximum velocity of 84.6 cm per second. N. integer in most cases could escape the attacks with a maximum velocity of 79.9 cm per second, displaying its typical tail swimming response. The attack of the stickleback lasted on average 0.2 s, whereas the escape response of the mysid prolonged for no longer than 0.1 s. Acceleration and deceleration times were different in predator and prey. Sticklebacks needed twice the time required for acceleration before terminating deceleration. Mysids required equal amounts of time for both phases. 25 % of the sticklebacks attacks were successful and aimed to the mysids centre of mass in 63 %. The energy expenditure for a successful attack was estimated with 2.5 mJ. The low capture success of the stickleback is discussed in respect to the high escape velocities and welldeveloped visual sense found in mysids. With such high escape abilities mysids should be ranked among euphausiids and copepods as one of the fastest members of the zooplankton.

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