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First published online October 18, 2006
Journal of Experimental Biology 209, 4254-4261 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02533
Use of urea as a chemosensory cloaking molecule by a bony fish

Division of Marine Biology and Fisheries, NIEHS Marine and Freshwater Biomedical Sciences Center, Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL 33149-1098, USA
* Author for correspondence at present address: Department of Biology, Portland State University, P.O. Box 75, Portland, OR 97207, USA (e-mail: jfb{at}pdx.edu)
Accepted 7 September 2006
Because urea is bioenergetically expensive to synthesize, few aquatic teleostean (bony) fish make or excrete much urea beyond early development and excrete the majority of nitrogenous waste as the readily diffusible ammonia. The gulf toadfish is one of a few adult teleostean fish that excretes predominately urea. Most studies of chemosensing by fish predators have focused on amino acids as odorants, but we tested the chemo-attractiveness of both urea and ammonia. We report that characteristic `prey-attack' behaviors by a key toadfish predator, gray snapper, were elicited by low ammonia concentrations (<100 nmol N l-1) and similar urea concentrations blunted the ammonia-induced component of attacks. Thus, urea functions as a cloaking molecule, explaining why toadfish co-excrete urea with ammonia. Furthermore, ammonia waste is an important chemical attractant for piscine predators.
Key words: urea, ammonia, chemosensory, predator-prey interaction, toadfish, snapper
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K. Phillips TOADFISH CLOAKED IN UREA J. Exp. Biol., November 1, 2006; 209(21): iii - iii. [Full Text] [PDF] |
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