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First published online April 23, 2004
Journal of Experimental Biology 207, 1855-1863 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.00992

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Escape behavior and escape circuit activation in juvenile crayfish during prey–predator interactions

Jens Herberholz^*, Marjorie M. Sen and Donald H. Edwards

Department of Biology, Georgia State University, Atlanta, GA 30303, USA

View larger version (116K): [in a new window]   Fig. 1. Prey–predator interactions between juvenile crayfish and dragonfly nymphs recorded with a digital video camera. (A) Single video frame showing a dragonfly nymph (Anax junius; left) in preparation for attacking a juvenile crayfish (Procambarus clarkii; right). (B) Three video frames, from top to bottom, illustrating a predatory strike by the dragonfly nymph (right; note the extension of the white-colored labium in the middle frame) that evokes an escape tail-flip by the crayfish (left, bottom). (C) Single video frame showing a dragonfly nymph feeding on a captured crayfish.

View larger version (46K): [in a new window]   Fig. 2. Correlation between field potentials and simultaneously recorded behavior from prey and predator during an attack. (A) A medial giant neuron mediated escape tail-flip produced by the crayfish in response to a frontal attack from the dragonfly nymph. The electrical recording from the bath electrodes is at the top and shows the potential generated by the predator attack followed by that of the prey escape. Below that trace, four video frames show the behavior of the animals (top view and side view via mirror image). The bars and arrows between them indicate the timing of each frame relative to the bath potential. The bottom of each frame displays the oscilloscope trace of that portion of the bath potential. The first two frames illustrate the initial period of the strike with the opening of the labial palps and the extension of the labium, respectively. The last two frames illustrate the successful escape response of the crayfish. For further explanation, see text. (B) Field potential measurement of the signal generated by the dragonfly nymph while attacking a mock prey. The initial part of the recording consists of small deflections that become larger towards the end of the potential.

View larger version (17K): [in a new window]   Fig. 3. Field potentials recorded with bath electrodes during predatory strikes. The onset of the predator's muscle potential is indicated with an arrowhead in all traces. (A) An electrical recording of potentials produced during a medial giant neuron mediated escape tail-flip. The large and phasic motor giant (MoG) neuron potential is followed by fast flexor (FF) muscle potentials. (B) Muscle potential recorded during a lateral giant mediated escape tail-flip. A smaller phasic MoG neuron potential is visible, followed by FF muscle potentials. (C) Muscle potential recorded during a non-giant mediated tail-flip. The signal consists of small FF muscle potentials only, and no large and phasic potential can be seen.

View larger version (13K): [in a new window]   Fig. 4. Targets and percentage of escape responses. (A) More attacks are directed towards the anterior parts of the crayfish (head and thorax) than towards the posterior parts (abdomen). (B) Most escape responses are generated by activity in the medial giant neuron (MG) while lateral giant mediated escapes (LG) are less frequent and non-giant mediated escape tail-flips (Non-G) are rare.

View larger version (34K): [in a new window]   Fig. 5. Distribution of all strikes and relative positions of dragonfly nymphs during attacks that evoked the three different types of tail-flips. Black circles indicate the position of the center of the labium on the crayfish's body for each strike and type of escape response. A schematic of the frontal part of the labium is shown to illustrate the size relationship (bottom left). Arrows around the crayfish demonstrate the relative position of the dragonfly nymph when the attacks were delivered.

View larger version (16K): [in a new window]   Fig. 6. Response latencies and success rates for escape for the three different types of tail-flips. (A) Latencies of crayfish escape after being hit by the dragonfly nymph (solid bars) or after being stimulated with a handheld probe (striped bars). During predator attacks, non-giant mediated tail-flips (Non-G) are executed with significantly longer latencies than medial giant (MG)- or lateral giant (LG)-mediated tail-flips. After stimulation with a probe, Non-G tail-flips also have significantly longer latencies than MG- or LG-mediated tail-flips. Non-G tail-flips evoked by the dragonfly nymph have significantly shorter latencies than probe-evoked ones. *P0.05, **P0.01. (B) MG- and LG-mediated tail-flips have a higher escape rate than Non-G-mediated tail-flips.

View larger version (18K): [in a new window]   Fig. 7. Non-giant (Non-G)-mediated escape tail-flips after capture. (A) An initial giant mediated escape tail-flip was followed by three Non-G-mediated tail-flips after the dragonfly nymph captured the crayfish. Note the difference in amplitude between the giant and the Non-G escape responses. (B) After unsuccessful initial medial giant (MG)- and Non-G-mediated escapes, crayfish frequently used Non-G-mediated tail-flips that resulted in high percentages of additional escapes after capture. After unsuccessful lateral giant (LG)-mediated escapes, crayfish used few Non-G-mediated tail-flips that resulted in few additional escapes.