QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online November 14, 2008
Journal of Experimental Biology 211, 3671-3676 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.019869

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Zani, P. A. Articles by Kram, R. Search for Related Content PubMed PubMed Citation Articles by Zani, P. A. Articles by Kram, R. Social Bookmarking                         What's this?

Low metabolic cost of locomotion in ornate box turtles, Terrapene ornata

Peter A. Zani^* and Rodger Kram

Department of Integrative Physiology, University of Colorado, Boulder, CO 80309, USA

^* Author for correspondence at present address: Department of Biology, Lafayette College, Easton, PA 18042, USA (e-mail: zanip{at}lafayette.edu)

Accepted 25 September 2008

Evolution has produced a wide range of body plans, but for a given body mass, the energetic cost of transport (COT) of terrestrial animals falls in a relatively narrow range. Previous research indicates that the COT depends on the proficiency of minimizing mechanical work performed, efficiency of performing that work, and cost of generating force to support weight. Turtles are unique in that their protective shell and shoulder-girdle articulation may eliminate the need for the `muscular sling'. In addition, turtles have slower, more efficient muscles than other vertebrates. However, slow locomotion may raise the COT by confounding mechanical-energy conservation via the inverted-pendulum mechanism. Our goal was to determine the metabolic COT and efficiency of a terrestrial turtle species during locomotion. We studied 18 ornate box turtles, Terrapene ornata. Walking speed was extremely slow (0.07±0.005 m s^–1). The average minimum COT was 8.0±0.70 J kg^–1 m^–1 attained at 0.1 m s^–1. Ornate box turtles consume only half the energy predicted by the allometric relationship for all terrestrial animals (15.9±0.35 J kg^–1 m^–1), and, thus, appear to be very economical walkers. When walking up a 24 deg. incline turtles moved significantly slower (0.04±0.004 m s^–1), but performed the extra work required to walk uphill with very high efficiencies (>49%). It appears that the co-evolution of a protective shell, the associated shoulder morphology, and very slow, efficient muscles produce both economical level walking and efficient uphill walking.

Key words: biomechanics, locomotion, energetic cost of transport, muscular efficiency, Terrapene

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?