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First published online September 19, 2008
Journal of Experimental Biology 211, 3095-3102 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.019059

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Fluid dynamics of feeding behaviour in white-spotted bamboo sharks

Sandra Nauwelaerts^1,*, Cheryl D. Wilga¹, George V. Lauder² and Christopher P. Sanford³

¹ Department of Biological Sciences, University of Rhode Island, Kingston, RI 02881, USA
² Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
³ Department of Biology, 114 Hofstra University, Hempstead, NY 11549, USA

^* Author for correspondence at present address: McPhail Equine Performance Center, Michigan State University, East Lansing, MI 48824, USA (e-mail: nauwelae{at}msu.edu)

Accepted 22 July 2008

Although the motor control of feeding is presumed to be generally conserved, some fishes are capable of modulating the feeding behaviour in response to prey type and or prey size. This led to the `feeding modulation hypothesis', which states that rapid suction strikes are pre-programmed stereotyped events that proceed to completion once initiated regardless of sensory input. If this hypothesis holds true, successful strikes should be indistinguishable from unsuccessful strikes owing to a lack of feedback control in specialized suction feeding fishes. The hydrodynamics of suction feeding in white-spotted bamboo sharks (Chiloscyllium plagiosum) was studied in three behaviours: successful strikes, intraoral transports of prey and unsuccessful strikes. The area of the fluid velocity region around the head of feeding sharks was quantified using time-resolved digital particle image velocimetry (DPIV). The maximal size of the fluid velocity region is 56% larger in successful strikes than unsuccessful strikes (10.79 cm² vs 6.90 cm²), but they do not differ in duration, indicating that strikes are modulated based on some aspect of the prey or simply as a result of decreased effort on the part of the predator. The hydrodynamic profiles of successful and unsuccessful strikes differ after 21 ms, a period probably too short to provide time to react through feedback control. The predator-to-prey distance is larger in missed strikes compared with successful strikes, indicating that insufficient suction is generated to compensate for the increased distance. An accuracy index distinguishes unsuccessful strikes (–0.26) from successful strikes (0.45 to 0.61). Successful strikes occur primarily between the horizontal axis of the mouth and the dorsal boundary of the ingested parcel of water, and missed prey are closer to the boundary or beyond. Suction transports are shorter in duration than suction strikes but have similar maximal fluid velocity areas to move the prey through the oropharyngeal cavity into the oesophagus (54 ms vs 67 ms).

Key words: hydrodynamics, DPIV, accuracy, behaviour, feeding, shark

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