Flow visualisation and high speed video analysis of water jets in the snapping shrimp (Alpheus heterochaelis) |
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Authors: | J Herberholz B Schmitz |
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Institution: | Institut für Zoologie, Technische Universit?t München, Lichtenbergstrasse 4, D-85747 Garching, Germany e-mail: Jens.Herberholz@bio.tum.de Tel.: +49-89-2891-3677; Fax: +49-89-2891-3674, DE
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Abstract: | Snapping shrimp (Alpheus heterochaelis) produce a fast, well-focused water jet by rapid closure of their specialised snapper claw. As shown previously, water jets
may injure the opponent in interspecific encounters (e.g. with small crabs) although no damage was observed in intraspecific
encounters. For conspecific receivers the jet represents a potential hydrodynamic signal and can be analysed with the help
of mechanosensory hairs. To gain more insight in the biophysical characteristics of the water jet we visualised and analysed
jets of tethered snapping shrimp using standard and high speed video recordings. Water jet width increases with increasing
distance from the snapper claw tip, and both width and distance increase with increasing snapper claw size. Water jet distances
do not increase with increasing claw cocking duration (building up muscle tension) but medium cocking durations of about 550 ms
result in longest distances. Mean water jet velocity is 6.5 m s−1 shortly after claw closure but rapidly decreases subsequently. At the mean distance between snapping conspecifics (9 mm)
water jet velocities produced by snapping shrimp with larger snapper claws are significantly higher than those of animals
with smaller claws. Interestingly, males with equal snapper claw size as females produce significantly faster water jets.
Accepted: 31 March 1999 |
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Keywords: | Snapping shrimp Alpheus heterochaelis Water jet Flow visualisation Agonistic encounter |
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