QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Fish, F. E. Articles by Nicastro, A. J. Search for Related Content PubMed PubMed Citation Articles by Fish, F. E. Articles by Nicastro, A. J.

Aquatic turning performance by the whirligig beetle: constraints on maneuverability by a rigid biological system

Frank E. Fish^1,* and Anthony J. Nicastro²

¹ Department of Biology, West Chester University, West Chester, PA 19383, USA
² Department of Physics, West Chester University, West Chester, PA 19383, USA

View larger version (151K): [in a new window]   Fig. 1. Turning maneuver of whirligig beetle (Dineutes horni) produced by rowing of the legs. The pattern of turning is indicated by the spiral waveform.

View larger version (144K): [in a new window]   Fig. 2. Winged-propulsion by the whirligig beetle during a turning maneuver. Single frame from a high-speed video recording (1000 frames s–1) shows deployment of the left wing and elytra. The beetle is turning to the left.

View larger version (13K): [in a new window]   Fig. 3. Model of forces (drag, vectored thrust) resulting in turning of the whirligig beetle. The path of motion is indicated by the curved arrow from the center of mass (solid dot) around the center of rotation (circled cross). Vectors for thrust (T), reaction force (R), elytra drag (E) and body drag (B) are indicated by the straight arrows. The propulsive force (T) provided by the sculling of the wing results in forward motion that is biased towards the left by the asymmetry of elytra drag exceeding body drag.

View larger version (14K): [in a new window]   Fig. 4. Relationship of swimming speed (U) and turning radius (R) for horizontal turning maneuvers by whirligig beetles. Squares and triangles represent turns produced by rowing of the legs; circles represent turns executed by winged-swimming. Triangles represent data for the minimum 20% of radii for all turns measured. The upper regression line (r=0.336, P<0.05; see text for the equation of the line) was fit to all data; the lower regression line (r=0.310, P<0.20) was fit to the minimum 20% of turning radii.

View larger version (16K): [in a new window]   Fig. 5. Relationship of turning rate, , and turning radius, R. Open circles represent swimming by rowing of the legs; filled circles represent turns executed by winged-swimming.

View larger version (16K): [in a new window]   Fig. 6. Relationship between centripetal acceleration, ac, and turning rate, , for whirligig beetles. Open circles represent swimming by rowing of the legs; filled circles represent turns executed by winged-swimming. The regression line (r=0.898, P<0.001; see text for the equation of the line) is for all turns.

View larger version (17K): [in a new window]   Fig. 7. Comparison of turning rate, , with respect to size. The line connects the beetle and submarine, which both have inflexible bodies. The value for relatively stiff tuna approaches the line. Data from Webb (1976, 1983), Hui (1985), Foyle and O'Dor (1988), Miller (1991), Blake et al. (1995), Gerstner (1999), Walker (2000) and Fish (1997, 2002).

View larger version (28K): [in a new window]   Fig. 8. Plot of centripetal acceleration, ac, as a function of turning rate, . Data from Webb (1976, 1983), Hui (1985), Blake et al. (1995), Walker (2000) and Fish (1997, 2002).