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Functional morphology of the gastric mills of carnivorous, omnivorous, and herbivorous land crabs

journal contribution
posted on 2010-01-01, 00:00 authored by Ben AllardyceBen Allardyce, Stuart Linton
Terrestrial decapods consume a wide variety of plant and animal material. The potential adaptations of carnivorous, omnivorous, and herbivorous terrestrial crustaceans were studied by examining the functional morphology of the gastric mill. Two closely related species from each feeding preference group were examined to identify which features of the mill were due to phylogeny and which were due to adaptation. The morphology of the gastric mill matched the diet well; the gastric mills of the carnivorous species (Geograpsus grayi and Geograpsus crinipes) possessed a blunt, rounded medial tooth and flattened lateral teeth with a longitudinal grinding groove. These features make them well suited to a carnivorous diet of soft animal tissue as well as hard material, such as arthropod exoskeleton. In contrast, the mill of the herbivorous gecarcinids (Gecarcoidea natalis and Discoplax hirtipes) consisted of a medial tooth with sharp transverse ridges and lateral teeth with sharp interlocking cusps and ridges and no grinding surface. These features would efficiently shred fibrous plant material. The morphology of the mill of the omnivorous coenobitids (Coenobita perlatus and Birgus latro) was more generalized toward a mixed diet. However, the mill of B. latro was more adapted to deal with highly nutritious food items, such as nuts and heavily calcified decapods. Its mill possessed lateral teeth with extended ridges, which sat close to the calcified cardiopyloric valve to form a flattened floor. Hard items trapped in the mill would be crushed against this surface by the medial tooth.

History

Journal

Journal of Morphology

Volume

271

Issue

1

Pagination

61 - 72

Publisher

John Wiley and Sons

Location

New York, N.Y.

ISSN

0362-2525

eISSN

1097-4687

Language

eng

Notes

Published Online: 21 Jul 2009

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2009, John Wiley and Sons