Prey capture in frogs: alternative strategies, biomechanical trade‐offs, and hierarchical decision making

Abstract

Frogs exhibit flexible repertoires of prey-capture behavior, which depend primarily on visual analysis of prey attributes. We review three examples of how visual cues are used to modulate prey-capture strategies. (1) Dyscophus guineti modulates tongue aiming in response to prey location. These frogs turn only their heads to apprehend prey located at azimuths o401. At azimuths 4401, the frogs switch from this strategy to one in which both head and tongue are aimed toward prey. (2) Rana pipiens modulates its feeding behavior in response to prey size, using tongue prehension for capturing small prey but switching to jaw prehension to capture large prey. (3) In Cyclorana novaehollandiae, visual processing of prey attributes involves hierarchical decision making. These frogs first assess prey size. For large prey, they ignore velocity but not shape. For small prey, they ignore shape but not velocity. Alternative prey-capture strategies are associated with biomechanical trade-offs that result from the interaction between the feeding apparatus and varying attributes of prey. Alternative strategies likely exist because biomechanical constraints prevent any one strategy from being effective over a range of prey attributes. Taken together, these studies emphasize the requirement that predators must somehow tune prey-capture kinematics simultaneously to multiple attributes of prey. In frogs, the choice among alternative prey-capture strategies involves a hierarchical decision-making process. Hierarchical decision making is expected to be widespread among animals. However, no previous studies were found except for humans, who frequently use this type of approach to make complex decisions.

Comparative neurophysiology of spatial luminance contrast sensitivity.

“…He also found, similar to other mammals, a good correlation between behavioral visual acuity and cut-off spatial frequency estimated from the sampling properties of the retinal ganglion cell mosaic. Monroy and Nishikawa (2011) studied the angular head movements of frogs during predatory behavior toward earthworms of different sizes. They found larger angular amplitudes for 2-3 cm prey and a smaller response for both larger-sized prey (low spatial frequencies) and especially smaller-sized prey (high spatial frequencies).…”

Flexibility in locomotor-feeding integration during prey capture in varanid lizards: effects of prey size and velocity

“…are flexible) (sensu Wainwright et al, 2008) in response to the physical, textural and mechanical properties of the ingested food item in many vertebrates (e.g. Deban, 1997;Nemeth, 1997;Valdez and Nishikawa, 1997;Ferry-Graham, 1998;Dumont, 1999;FerryGraham et al, 2001;Vincent et al, 2006;Reed and Ross, 2010;Monroy and Nishikawa, 2011). Such variability in feeding movements has been documented extensively in squamate lizards during both the capture and intra-oral transport and processing of food (e.g.…”

“…Deban, 1997;Ferry-Graham, 1998;Delheusy and Bels, 1999;Vincent et al, 2006;Freeman and Lemen, 2007;Schaerlaeken et al, 2007) and prey mobility (e.g. Ferry-Graham, 1998;Ferry-Graham et al, 2001;Montuelle et al, 2010;Monroy and Nishikawa, 2011) in a wide array of vertebrates.…”

Possible neural network mediating jaw opening during prey-catching behavior of the frog

“…ଝ Grant Support: This work was supported by grants from the Hungarian Academy of Sciences (MTA TKI 11008) and Framing, 1989;Weerasuriya, 1983Weerasuriya, , 1989. In ranid frogs and toads the characteristic pattern for feeding is called tongue prehension behavior (TPB) (Monroy and Nishikawa, 2011;Nishikawa, 2000). Although feeding movements are essentially organized by this genetically predetermined program, various sensory signals may provide flexible fine tuning for the ongoing motor action (Anderson and Nishikawa, 1993;Anderson, 2001;Harwood and Anderson, 2000;Nishikawa and Gans, 1992;Weerasuriya, 1989).…”