Functional and evolutionary morphology of lingual feeding in squamate reptiles: phylogenetics and kinematics

Abstract

Use of the tongue as a prehensile organ during the ingestion stage of feeding in lizards was studied cinegraphically in seven species. Within Squamata, lingual prehension is limited to a single clade, the Iguania (Iguanidae, Agamidae and Chamaeleontidae), which includes all ‘fleshy‐tongued’ lizards. All remaining squamates (Scleroglossa) use the jaws alone for prey prehension. Lingual prehension and a ‘fleshy’ tongue are primitive squamate characteristics. Kinematically, lingual ingestion cycles are similar to previously described transport cycles in having slow open, fast open, fast close and slow close‐power stroke phases. Tongue movements are sequentially correlated with jaw movements as they are in transport. However, during ingestion, anterior movement of the tongue includes an extra‐oral, as well as intra‐oral component. Tongue protrusion results in a pronounced slow open‐II phase at a large gape distance. A high degree of variability in quantitative aspects of ingestion and transport cycles suggests that modulation through sensory feedback is an important aspect of lizard feeding. Preliminary evidence indicates an important role for hyoid movement in tongue protrusion. Our results are consistent with the Bramble & Wake (1985) model generalized feeding cycle and support their contention that specialized feeding mechanisms often represent modifications of a basic pattern, particularly modification of the slow open phase.

Prey capture kinematics of ant-eating lizards

“…The gape profile during prey capture in P. vitticeps is similar to that described for other iguanian J. J. Meyers and A. Herrel Schwenk and Throckmorton, 1989;Delheusy and Bels, 1992;Herrel et al, 1995) and displays the kinematic phases characteristic of the generalized lower tetrapod feeding model (Bramble and Wake, 1985). Although this model was originally developed to describe prey processing and transport, it has been aptly applied to prey capture as well Bels, 1992, 1999;Herrel et al, 1995;Smith et al, 1999) and will be used here to describe the general features of the prey capture cycle in the four species.…”

“…Most studies of lizard feeding behavior have since supported the presence of a basic pattern, but have also identified significant variation in feeding movements (e.g. Schwenk and Throckmorton, 1989;Kraklau, 1991;Urbani and Bels, 1995;Delheusy and Bels, 1999;McBrayer and Reilly, 2002a). While these studies have laid a foundation for comparisons of lizard groups, they also reveal a striking gap in the literature regarding the feeding movements of dietarily specialized lizards.…”

Ultrastructural Studies on the Tongue of Some Egyptian Lizards 1-Scincine Lizards Chalcides Oscellatus and Chalcides Sepsoides (Lacertilia, Scincidae)

“…According to [25][26][27][28][29] lizards showed different morphological and histological structures of the tongue among species in different habitats. The morphology of the tongue of both C. ocellatus and C. sepsoides is characterized by smooth and bifurcated distal portion followed by different typed of lingual papillae that are distributed in the anterior, middle and posterior lingual regions.…”

Quantitative analysis of the effect of prey properties on feeding kinematics in two species of lizards

“…It has been hypothesized that there are functional roles for the various phases of the gape cycle during prey transport in lizards (Bramble and Wake, 1985;Schwenk and Throckmorton, 1989;Kraklau, 1991;Urbani and Bels, 1995;Schwenk, 2000), and the results presented here can address those hypotheses. Most functional hypotheses relating to the phases of the gape cycle in lizards have involved the SO phase, but the FO, FC and SC phases have also been addressed in various studies.…”