The Tail Flip Escape Response of the Brown Shrimp Crangon crangon (L.) in the Context of Predator-Prey Interactions

Arnott, Stephen Andrew (1996) The Tail Flip Escape Response of the Brown Shrimp Crangon crangon (L.) in the Context of Predator-Prey Interactions. PhD thesis, University of Glasgow.

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This investigation has used high speed and conventional video techniques to investigate the tail flip escape behaviour of the brown shrimp Crangon crangon (L.) in the context of predator-prey interactions. Shrimp length has a significant effect upon the displacement, velocity and acceleration achieved during a tail flip. Displacement per tail flip increases from approximately 12 mm in small (10 mm) shrimps, to 90 mm in large (> 60 mm) shrimps. Mean velocity, maximum velocity and maximum acceleration increase from approximately 0.4 m.s-l, 0.6 m.s-1 and 70 m.s-2 respectively in small shrimps, to 1.1 m.s-1, 1.8 m.s-1 and 160 m.s-2 in shrimps of between 50-60 mm, but performance in shrimps larger than this declines slightly. The body flexion movement of Crangon crangon during tail flips is relatively symmetrical, with the result that both the head region and the tail region are moved through the water with respect to the shrimp's centre of mass. This is associated with the use of a head fan (formed by expansion of the antennal scales) as well as a tail fan (formed by expansion of the uropods) for generating thrust. Removal of the head fan results in a decline in tail flip velocity by 35 %, compared with a 58 % decline when the tail fan is removed. Escapes by Crangon crangon have been found to consist of either a single tail flip, or a series of tail flips which together constitute an escape swimming bout. The first flexion phase of an escape translates the shrimp laterally or vertically depending on whether its body is rotated about the longitudinal axis during the initial stages of an escape. If the first flexion is vertical, a lateral roll often occurs during the following re-extension phase. Consequently, subsequent tail flips of an escape occur with the shrimp swimming on its side, and steering in the horizontal plane is achieved by modifying the angle of rotational pitch between one tail flip and the next. This tail flip mechanism is in direct contrast to that of many other types of larger decapods, which instead tend to tail flip in an upright body position. Horizontal escape trajectories of shrimps have been investigated in an arena with a hard substratum (preventing shrimps from burying) using both a natural stimulus (juvenile cod, Gadus morhua) and an artificial stimulus (a wooden rod) to evoke tail flip responses. Both types of stimuli result in the first tail flip of a response being laterally (rather than vertically) directed, and generate similar escape trajectories. When a shrimp is attacked from either head-on or tail-on, the probability of an escape occurring to the left side of the shrimp is approximately equal to an escape occurring to the right side. If an attack occurs from the side of a shrimp, escapes are directed preferentially to the contralateral side of the stimulus. Also, if the shrimp is exposed to a lateral sub-threshold pre-stimulus before being attacked from the front or the rear, escapes are directed preferentially to the contralateral side of the prestimulus. The escape angle of the first tail flip of a response (with respect to the shrimp's body axis, where the head = 0

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: Douglas Neil
Keywords: Zoology, Behavioral sciences
Date of Award: 1996
Depositing User: Enlighten Team
Unique ID: glathesis:1996-74986
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 27 Sep 2019 14:45
Last Modified: 27 Sep 2019 14:45

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