Environmental Biology of Fishes

, Volume 40, Issue 3, pp 283–302

Endothermy in fishes: a phylogenetic analysis of constraints, predispositions, and selection pressures

  • Barbara A. Block
  • John R. Finnerty

DOI: 10.1007/BF00002518

Cite this article as:
Block, B.A. & Finnerty, J.R. Environ Biol Fish (1994) 40: 283. doi:10.1007/BF00002518


Endothermy, the ability to raise body temperature by internal heat production, is unusual in teleost fishes and has only been documented within one suborder, the Scombroidei. Two separate modes of endothermy have evolved in the scombroidei; tunas warm their muscles, brain and viscera using heat exchangers in the circulation to these metabolically active tissues while billfishes and one primitive mackerel have a thermogenic organ situated beneath the brain. Both modes of endothermy emphasize common themes. Large body size coupled with heat exchangers are necessary to reduce convective and conductive heat exchange. A tissue with a high oxidative capacity is required for heat generation. Studies based upon morphology and mitochondrial DNA analyses indicate that endothermy has evolved independently at least three times within the scombroid lineage. Mapping of-morphological and physiological traits on a molecular phylogeny for scombroids provides evidence of selective pressures favoring evolution of diverse endothermic styles. The new results suggest anatomical constraints prevent most fish from using the tuna form of endothermy and indicate a possible linkage between endothermy and locomotory style (thunniform or sub-carangiform).

Key words

Endothermy Phylogeny Character evolution Scombroidei Tunas Billfishes 

Copyright information

© Kluwer Academic Publishers 1994

Authors and Affiliations

  • Barbara A. Block
    • 1
  • John R. Finnerty
    • 1
  1. 1.Department of Organismal Biology and AnatomyThe University of ChicagoChicagoUSA
  2. 2.Hopkins Marine StationStanford UniversityPacific GroveUSA

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