Warm-blooded Fish?

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."

Re:I knew it!

[caddisfly]

"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

It's not a reptile.

[dangerweasel]

It is a cartilagenous fish. Common ancestor somewhere way back, but still different. This is also not localized to this fish. Tuna and other sharks exhibit this. It is called regional endothermy, or also heterothermy. We just learned about it in Vertebrate Zoology. It has been hypothesized it allows them a huge increase in swimming speed for attacking prey.

Re:So...

[jx100]

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.

tuna also

[YesIAmAScript]

http://en.wikipedia.org/wiki/Tuna [wikipedia.org]

Wow, not sure why it is news that some fish are warm-blooded.

The warm-bloodedness of tuna also makes allows them to be very good swimmers even in cold water.

Re:Sharks are not fish

[spongebobsquarepants]

Sharks are fish, just not bony fish. Sharks secondarily lost their bony structure, giving way to cartilaginous skeletons; giving rise to the Class Chondrichthyes. Bony fish fall under Class Osteichtyes.

Re:Rattlesnakes also warm blooded

[spongebobsquarepants]

The correct terminology is not 'warm blooded' or 'cold blooded.' Ther correct terms are endothermic and ectothermic, respectively, meaning that heat is obtained either internally or externally. For instance, some lizards maintain (through behavioral thermoregulation) body temperatures warmer than those of humans, even when the air temperature is well below body temperature.

Re:Working muscles give off heat?

[krautcanman]

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.

Re:Rattlesnakes also warm blooded

[Ksisanth]

Actually, rattlesnakes are ovoviviparous, meaning they hold the eggs inside until they hatch and then give live birth. (Note for anyone who would kill a gravid female close to "delivery": those babies can still come out without any help from their mother.) Most boas are also live-bearers.

But for those species which are oviparous, there are some which will incubate their eggs by coiling around them and twitching, using these muscular spasms to increase their temperature up to ~7C. IIRC, some python species will do this, but it isn't typical.

Re:I knew it!

[BKX]

Sharks are not invertabrates. They are vertabrates with a full skeleton. That skeleton just happens to be a softer relative of bone called cartilage. That's why all fish are vertebrates and there's a class of vertebrates called cartilagenous fish.

Metric countertranslation

[Gorimek]

68 - 86F = 20.0 - 30.0C

47F = 8.3C