Is post-feeding thermotaxis advantageous in elasmobranch fishes?

Authors

  • V. Di Santo,

    Corresponding author
    1. Department of Biology, University of West Florida, 11000 University Parkway, Pensacola, FL 32514, U.S.A.
      Author to whom correspondence should be addressed at present address: Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215, U.S.A. Tel.: +1 617 353 6969; email: vdisanto@bu.edu
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  • W. A. Bennett

    1. Department of Biology, University of West Florida, 11000 University Parkway, Pensacola, FL 32514, U.S.A.
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Author to whom correspondence should be addressed at present address: Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215, U.S.A. Tel.: +1 617 353 6969; email: vdisanto@bu.edu

Abstract

The effects of post-feeding thermotaxis on ileum evacuation and absorption rates were examined in the laboratory using two elasmobranch species, the Atlantic stingray Dasyatis sabina, which inhabits thermally variable environments, and the whitespotted bamboo shark Chiloscyllium plagiosum, a stenothermic fish living on Indo-Pacific reefs. Experiments at temperatures similar to those experienced in nature revealed temperature change had no significant effect on C. plagiosum absorption or evacuation rates, suggesting stenothermic sharks cannot exploit temperature differences as a means to improve digestion efficiency. On the other hand, D. sabina showed significantly lower evacuation and absorption rates at lower temperatures. The relative decrease was greater for evacuation (Q10 = 3·08) than absorption rates (Q10 = 2·20), resulting in a significant increase in total absorption, suggesting D. sabina can benefit from using shuttling behaviour to exploit thermal variability in their environment to maximize energetic uptake.

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