TY - JOUR
T1 - Foraging to the rhythm of ocean waves
T2 - porcelain crabs and barnacles synchronize feeding motions with flow oscillations
AU - Trager, Geoff C.
AU - Coughlin, David
AU - Genin, Amatzia
AU - Achituv, Yair
AU - Gangopadhyay, Ashis
PY - 1992/11/23
Y1 - 1992/11/23
N2 - Suspension-feeding activity patterns of four benthic crustacean species (2 porcellanid crabs and 2 balanomorph barnacles) were studied in simulated wave-action (oscillating flow in a laboratory flow tank). The hypothesis that the frequency of rhythmic suspension-feeding motions observed in oscillating flow depends on the frequency of flow oscillation was tested. Also, we examined the effect of flow oscillation frequency on time allocation to food-particle-trapping versus non-trapping components of feeding behavior, as an indication of how the energetic gain-to-cost ratio of feeding varies with flow regime. A newly developed flow pattern generator, consisting of computer programs interfaced with a flow tank motor, was used to produce various oscillating flow regimes (0.16-0.65 Hz. 6.2-12.1 cm·s-1 maximum velocity). Laser-optics, fiber optics, and video equipment were used to record behavior and to determine water flow velocities non-intrusively, by tracking the video-recorded movement of back-lit particles suspended in flowing seawater. All animals tested rhythmically reoriented suspension-feeding fans in oscillating flow so that the cup-shaped fans faced concave-upstream. At all test frequencies, the frequency of the cyclic motions of feeding append ages matched the frequency of flow directional oscillation precisely. Also, all species behaviorally anticipated changes in flow direction, by beginning to reorient feeding fans to changing flow direction before the water itself had reversed flow direction (i.e the animals responded when water was decelerating). This anticipatory behavior allowed animals feeding in wave-action to avoid missing full fan extension during part of the peak velocity range of an upcoming pulse of flow, as would have happened if they had waited until flow direction changed to reorient appendages. That animals actively track wave frequency so precisely with their feeding fan movements suggests than, in natural habitats, wave frequency is a critical factor for certain consumers that affects the energetics of feeding activity. Video analysis showed that as flow oscillation frequency decreased, all animals spent a greater fraction of feeding time trapping suspended food particles with fans fully extended into flow, and a corresponding smaller fraction of time engaged in the muscular activity of removing trapped particles and reorienting feeding fans. These changes suggest an increase in energetic feeding gain-to-cost ratio with a decrease in flow oscillation frequency.
AB - Suspension-feeding activity patterns of four benthic crustacean species (2 porcellanid crabs and 2 balanomorph barnacles) were studied in simulated wave-action (oscillating flow in a laboratory flow tank). The hypothesis that the frequency of rhythmic suspension-feeding motions observed in oscillating flow depends on the frequency of flow oscillation was tested. Also, we examined the effect of flow oscillation frequency on time allocation to food-particle-trapping versus non-trapping components of feeding behavior, as an indication of how the energetic gain-to-cost ratio of feeding varies with flow regime. A newly developed flow pattern generator, consisting of computer programs interfaced with a flow tank motor, was used to produce various oscillating flow regimes (0.16-0.65 Hz. 6.2-12.1 cm·s-1 maximum velocity). Laser-optics, fiber optics, and video equipment were used to record behavior and to determine water flow velocities non-intrusively, by tracking the video-recorded movement of back-lit particles suspended in flowing seawater. All animals tested rhythmically reoriented suspension-feeding fans in oscillating flow so that the cup-shaped fans faced concave-upstream. At all test frequencies, the frequency of the cyclic motions of feeding append ages matched the frequency of flow directional oscillation precisely. Also, all species behaviorally anticipated changes in flow direction, by beginning to reorient feeding fans to changing flow direction before the water itself had reversed flow direction (i.e the animals responded when water was decelerating). This anticipatory behavior allowed animals feeding in wave-action to avoid missing full fan extension during part of the peak velocity range of an upcoming pulse of flow, as would have happened if they had waited until flow direction changed to reorient appendages. That animals actively track wave frequency so precisely with their feeding fan movements suggests than, in natural habitats, wave frequency is a critical factor for certain consumers that affects the energetics of feeding activity. Video analysis showed that as flow oscillation frequency decreased, all animals spent a greater fraction of feeding time trapping suspended food particles with fans fully extended into flow, and a corresponding smaller fraction of time engaged in the muscular activity of removing trapped particles and reorienting feeding fans. These changes suggest an increase in energetic feeding gain-to-cost ratio with a decrease in flow oscillation frequency.
KW - Oscillating flow frequency
KW - Rhythmic feeding motion
KW - Suspension-feeding crustacean
UR - http://www.scopus.com/inward/record.url?scp=0027065621&partnerID=8YFLogxK
U2 - 10.1016/0022-0981(92)90137-Y
DO - 10.1016/0022-0981(92)90137-Y
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AN - SCOPUS:0027065621
SN - 0022-0981
VL - 164
SP - 73
EP - 86
JO - Journal of Experimental Marine Biology and Ecology
JF - Journal of Experimental Marine Biology and Ecology
IS - 1
ER -