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Biol Lett. 2006 Dec 22;2(4):485-7.

Rotational feeding in caecilians: putting a spin on the evolution of cranial design.

Author information

1
Department of Biology, University of Antwerp, Universiteitsplein 1, 2610 Antwerpen, Belgium. john@measey.com

Abstract

Caecilians are a poorly known group of amphibians with a highly derived skull and cranial musculature that has evolved in response to their specialized head-first burrowing lifestyle. They possess a unique jaw-closing system, which is shown to be capable of generating considerable bite forces for its head width (1.09+/-0.34 and 0.62+/-0.31 N for Schistometopum thomense and Boulengerula taitanus, respectively). However, comprehensive dietary studies indicate that there is no need for large bite forces, since most caecilians appear to be generalist predators of subterranean macrofauna. Here, we demonstrate, based on in vivo external and X-ray video recordings of animals feeding, that long-axis body rotations are used independent of prey size by these two species of caeciliid caecilians when feeding underground. Further, we show that individuals are capable of generating a substantial spinning force, which is greater than their bite force (1.35+/-0.26 and 1.02+/-0.18 N, respectively). These observations shed light on the functional and the evolutionary significance of several unique features of the cranial design in derived caecilians; spinning may allow the individuals to judge prey size and subsequently reduce oversized prey within gape limits.

PMID:
17148268
PMCID:
PMC1833987
DOI:
10.1098/rsbl.2006.0516
[Indexed for MEDLINE]
Free PMC Article

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