Prey capture kinematics of ant-eating lizards

Abstract

While morphological and behavioral feeding specializations are obvious in many vertebrate groups, among lizards there appear to be few dietary specialists. By comparing the prey capture kinematics and overall feeding behavior in two highly specialized ant-eating lizards (Moloch horridus and Phrynosoma platyrhinos) with those of two closely related dietary generalists (Pogona vitticeps and Uma notata), we investigate whether dietary specialization has been accompanied by changes in the function and use of the feeding system. We quantified kinematic variables from high-speed video recordings (200-250·frames·s -1 ) of each species feeding on ants. Prey capture was strikingly different in M. horridus to that of other species, being characterized by a suite of unusual behaviors including the lack of a body lunge, faster tongue protrusion, reduced prey processing and, most notably, the ability to modulate the slow open phase of the gape cycle. In concert, these traits make a single feeding event in M. horridus faster than that in any other iguanian lizard studied to date. Prey capture behavior in P. platyrhinos is kinematically more similar to U. notata and P. vitticeps than to M. horridus, but the ant specialists are similar in that both lack distinct prey processing behaviors, resulting in faster overall capture and feeding events. While ant feeding in P. vitticeps is faster than feeding on other prey, the duration of a single feeding event is still four times longer than in either ant specialist, because of extensive prey processing. Additionally, a phylogenetic comparison of ant specialist lizards with dietary generalists revealed that ant-eating lizards require significantly less time to capture and process prey. Thus there are not only significant behavioral modifications in these ant-eating lizards, but also multiple strategies among specialists, suggesting differing selective pressures or phylogenetic constraints in the evolution of ant eating in lizards.

Locomotor–feeding coupling during prey capture in a lizard(Gerrhosaurus major): effects of prehension mode

“…Tongue prehension, on the other hand is slower and is characterized by a tongue protrusion-retraction cycle and tongue deformation similar to that observed for iguanian, scincid and gerrhosaurid lizards (Schwenk and Throckmorton, 1989;Kraklau, 1991;Herrel et al, 1995;Urbani and Bels, 1995;Smith et al, 1999;Meyers and Nishikawa, 2000;Schwenk, 2000). Indeed, in most species using tongue prehension, the tongue deforms and contacts the prey with its dorsal surface (Delheusy et al, 1994) (but see Meyers and Herrel, 2005). The initialization of the strike is also highly different between tongue and jaw prehension: when using its jaws to capture prey G. major extends its forelimbs and raises its head and neck to position its jaws dorsal to the prey, which is crucial for the jaws to be able to grasp the prey (Frazzetta, 1983;Delheusy et al, 1995).…”

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

“…Indeed, by feeding routinely on the same food, selective pressures are imposed on the feeding structures to optimize prey-capture efficiency (e.g. Herrel et al, 1997;Ralston and Wainwright, 1997;Aguirre et al, 2003;Meyers and Herrel, 2005;Herrel and De Vree, 2009). As changes in food properties have been shown here to affect locomotor-feeding integration in lizards using jaw prehension, particular food properties are suggested to require particular locomotor-feeding integration patterns (see Fig.9), and specialization in locomotor-feeding integration may occur in response to diet.…”

“…Hotton, 1955;Herrel et al, 1997;Herrel et al, 2004;Santana et al, 2011;Kupczik and Stynder, 2012), hyolingual apparatus (e.g. Bels et al, 1994;Schwenk, 2000;Bels, 2003;Meyers and Herrel, 2005;Schwenk and Rubega, 2005; and digestive track (O'Grady et al, 2005;Herrel et al, 2008;Griffen and Mosblack, 2011). From a functional perspective, feeding movements vary (i.e.…”

“…Consequently, in such organisms, the form and function as well as the behavioral capabilities of the feeding system are known to be specialized for handling the particular characteristics of their diet (e.g. Herrel et al, 1997;Ralston and Wainwright, 1997;Korzoun et al 2001;Korzoun et al, 2003;Aguirre et al, 2003;Homberger, 2003;Meyers and Herrel, 2005;Herrel and De Vree, 2009). In contrast, organisms that typically feed on a wide variety of food items (i.e.…”

Comparative histological characterization of the tongue in two reptiles; Scincus scincus (Scincidae) and Uromastyx ornata (Agamidae) in relation to diet

“…Reptile tongue is a muscular organ situated in the oral cavity with some different roles during the process of feeding, including prey capture, food transport, the preparation of bolus, tasting foods, swallowing, and drinking (Schwenk, 2000;Meyers and Herrel, 2005;Schaerlaeken et al, 2007).…”