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Warm-blooded Fish?

Posted by Hemos on from the sounds-mighty-fishy-fishy-har-de-har dept.

DIY News writes "Scientists now have direct evidence that the north Pacific salmon shark maintains its red muscle at 68-86 degrees Fahrenheit, much warmer than the 47 F water in which it lives. The elevated muscle temperature presumably helps the salmon shark survive the cold waters of the north Pacific and take advantage of the abundant food supply there. The heat also appears to factor into the fish's impressive swimming ability."

3 of 342 comments (clear)

  1. Re:I knew it! by caddisfly · · Score: 4, Informative
    "Damn reptiles... always trying to copy us!"

    ...and this is why we need to continue to teach *science* in science class 'cause last time I checked, salmon sharks were not reptiles.

    These findings just confirm the "above ambient temp" findings that have been known for quite a while with bluefin tuna, other big sharks, etc.

    ...the evolutionary implications are that these "heater" systems allowed these predators to extend their hunting range and hunting efficiency by moving into and operating in colder waters and thus increasing the amount of food available to them --- presto, evolutionary success!

    ...that was until the commercial fishing and technology came along to start wiping them out

  2. Re:So... by jx100 · · Score: 3, Informative

    A theory can predict. A theory has rules and models. A theory has mountains of evidence pointing towards its validity.

    Evolution fits all these parameters. ID fits none.

  3. Re:Working muscles give off heat? by krautcanman · · Score: 3, Informative

    These sharks, along with makos, tunas and thresher sharks have countercurrent heat exchange vasculature that allows them to maintain elevated body temperatures, so this finding isn't necessarily new. The ability to maintain elevated temperatures often allow these animals to make deep foraging dives into cold water, or, in the case of the salmon shark, live in colder waters. The consequence of cold muscles is that you also move slowly (think of how your hands feel when you forget to wear gloves when it's really cold out). It's also thought that by maintaining elevated brain temperatures these fish are better at processing visual information, among other things (who knows - foraging behaviors?).

    Here are the references to several manuscripts on the subject:

    Bernal, D., Dickson, K. A., Shadwick, R. E. and Graham, J. B. (2001a). Review: Analysis of the evolutionary convergence for high performance swimming in lamnid sharks and tunas. Comp. Biochem. Physiol. A Mol. Integr. Physiol. 129, 695-726.

    Bernal, D., Sepulveda, C. and Graham, J. B. (2001b). Water-tunnel studies of heat balance in swimming mako sharks. J. Exp. Biol. 204(23), 4043-2054.

    Bernal, D., Sepulveda, C., Mathieu-Costello, O. and Graham, J. B. (2003). Comparative studies of high performance swimming in sharks. I. Red muscle morphometrics, vascularization, and ultrastructure. J. Exp. Biol. 206, 2831-2843.

    Carey, F. G. and Teal, J. M. (1969). Mako and porbeagle: warm-bodied sharks. Comp. Biochem. Physiol. 28, 199-204

    Carey, F.G., Casey, J. G., Pratt, H. L., Urquhart, D. and McCosker, J. E. (1985). Temperature, heat production and heat exchange in lamnid sharks. Mem. S. Calif. Acad. Sci. 9, 92-108

    Carey, F. G., Teal, J. M., Kanwisher, J. W. and Lawson, K.D. (1971). Warm bodied fish. Am. Zool. 11, 135-145

    Graham, J. B., Koehrn, F. J. and Dickson, K. A. (1983). Distribution and relative proportions of red muscle in scombrid fishes: consequences of body size and relationships to locomotion and endothermy. Can. J. Zool. 61, 2087-2096.