Ontogeny of Suction Feeding Capacity in Snook, Centropomus undecimalis PETER C. WAINWRIGHT 1Ã , STEPHEN H. HUSKEY 2 , RALPH G. TURINGAN 3 , AND ANDREW M. CARROLL 1 1 Section of Evolution & Ecology, University of California, Davis, California 95616 2 Department of Biology, Western Kentucky University, Bowling Green, Kentucky 42101 3 Department of Biological Sciences, Florida Institute of Technology, Melbourne, Florida 32901 ABSTRACT The ontogeny of suction feeding performance, as measured by peak suction generating capacity, was studied in the common snook, Centropomus undecimalis. Suction pressure inside the buccal cavity is a function of the total expansive force exerted on the buccal cavity distributed across the projected area of the buccal cavity. Thus, the scaling exponent of peak suction pressure with fish standard length was predicted to be equal to the scaling exponent of sternohyoideus muscle cross-sectional area, found to be 1.991, minus the scaling exponent for the projected buccal cavity area, found to be 2.009, equal to 0.018. No scaling was found in peak suction pressure generated by 12 snook ranging from 94 to 314 mm SL, supporting the prediction from morphology. C. undecimalis are able to generate similar suction pressures throughout ontogeny. J. Exp. Zool. 305A:246–252, 2006. r 2006 Wiley-Liss, Inc. Most fish use suction feeding to capture prey, a behavior that involves the rapid expansion of the mouth and buccal cavity, causing water to flow into the mouth (Fig. 1; Ferry-Graham and Lauder, 2001). The rapid cranial expansion creates a drop in pressure inside the buccal cavity (Van Leeuwen and Muller, ’83), the magnitude of which has been used as a metric of suction feeding performance (Norton and Brainerd, ’93; Nemeth, ’97) since all of the forces that suction feeders exert on their prey increase as a function of suction pressure. Comparative studies have confirmed that species vary considerably in their capacity to generate suction pressure, with over an order of magnitude range in peak pressure found among teleost species (Lauder, ’80; Norton and Brainerd, ’93; Nemeth, ’97; Carroll et al., 2004). While inter- specific data are accumulating rapidly, it is less clear how suction feeding performance scales within species (Richard and Wainwright, ’95; Wainwright and Shaw, ’99). Do fish generate similar suction pressures throughout their lives, or does the capacity to generate suction increase as fish get larger and stronger? The answer to this question has important implications on how we view the comparative data on suction pressure and for understanding the dynamics of growth in fish predators that typically change their feeding habits as they grow. In the present study, the scaling of suction pressure capacity was compared with morphologically based predictions of this scaling relationship in the common snook, Centropomus undecimalis (Bloch). MATERIALS AND METHODS The magnitude of suction pressure is equal to the buccal expansion forces exerted per unit of the projected buccal cavity area (Carroll et al., 2004). One estimate of the scaling of suction pressure capacity would involve measuring both the scaling of the expansive forces and the scaling of projected buccal area. Each of these variables can be related to a measure of body size, such as fish standard length using the allometric equation: Variable ¼ aL X : ð1Þ Published online in Wiley InterScience (www.interscience.wiley. com). DOI: 10.1002/jez.a.255. Received 28 March 2005; Accepted 7 October 2005 Grant sponsor: National Science Foundation GrantIOB-0444554. Ã Correspondence to: Dr. P.C. Wainwright, Section of Evolution & Ecology, University of California, One Shields Avenue, Davis, CA 95616. E-mail: pcwainwright@ucdavis.edu r 2006 WILEY-LISS, INC. JOURNAL OF EXPERIMENTAL ZOOLOGY 305A:246–252 (2006)