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."

Comments

Other warm-blooded "cold-blooded" creatures

[G4from128k]

Many insects also create intentionally elevated body temperatures (generally through shivering). Moths, bees, dung beetles all generate heat to enable greater activity under cold conditions.

For example. Honeybees generate heat in the winter to keep the hive warm and use heat to kill predatory wasps -- surrounding the wasp, heating up to 45 C (113 F) and killing the attacker.

Re:Other warm-blooded "cold-blooded" creatures

[JasonKChapman]

Or did I miss something?

You did. Thermodynamically, extra effort is extra effort, even if that extra effort involves burning calories to produce a special behavior rather than burning calories to feed a special organ. Evolutionarily, it doesn't really matter--in fact it makes sense--that many different mechanisms evolved toward the same general end. A species that already accomplishes a particular goal in one manner probably won't evolve toward a different method unless some other advantage comes with it.

More interesting than the sharks in the article, I think, is the eye-heating organs that marlin and sailfish have evolved. The last theory I read is that helps them see more clearly, for hunting, in the deep cold water. They evolved just enough to accomplish the goal and no more. Give them a couple of centuries of much colder water, and I'm sure they'd end up heating their whole blood supply, too.

Not surprising, and not really "warm-blooded"

[dpbsmith]

The distinction is not between "cold-blooded" and "warm-blooded" animals but between poikilotherms, whose body temperature is the same as that of the environment, and homeotherms, whose body temperature is closely regulated and held within a normal range of a couple of degrees or less

On the one hand, practically every poikilotherm that's been studied actually thermoregulates in some ways. Very few of them truly assume the temperature of their environment.

On the other hand, "maintaining" temperature at "68-86 degrees Fahrenheit" -- 77 degrees plus or minus 9--is far from comparable to the degree of thermoregulation shown by mammals. Nine degrees too high or too low is enough to kill you, and most mammals.

It's interesting to learn how another kind of poikilotherm performs a crude kind of thermoregulation, but by no means earthshaking.

I thought there were a bunch

[Nf1nk]

As a long time deep sea fisherman I thought there were a bunch of fish who lived with an elivated core temperature. Many of the red meat fast swimming open ocean fish (such as tuna, dorado, baracuda, swordfish) are decidely warm when you pull them in and have a radicaly different muscle structure than what you see with slow moving cold fish. Also the tend to have many fewer visable internal parasites, which I always associated with having a much different metablism.

Re:So...

[barjam]

http://en.wikipedia.org/wiki/Wedge_strategy

Interesting...

Re:So...

[MightyMartian]

Evolution does matter. On one hand it is the overarching and unifying theory of biology.

It also matters because ID is not science. It is not testable. It is not falsifiable. It isn't even a theory save in the most general and non-specific meaning of the word. More importantly however, is that public schools in the US are not supposed to be places of religious indoctrination, and ID is formulated as a legalistic scam to sneak Creationism past the 1st Amendment.

Evolution is not a religion. It is not a bit of wild-ass speculation. Not all ideas are created equal, and in the world of science there is no debate. Any theory that seeks to replace evolution is going to have to explain the evidence, and DesignerDidIt explains nothing whatsoever.

Fish != fish !?

[Shark]

This is still a bit of a debate, but:
Shark != Bony Fish, Sharks = Cartilaginous fish

The distinction is important, because taxonomy-wise, that makes them as different from 'fish' (bony) as mammals, amphibians, reptiles or avians. It's a split at the class level. A warm blooded shark is not as impressive as a warm blooded bony fish would be.

Of course, since chondrichythes (cartilaginous fish) and osteichythes (bony fish) still contain the word chythes (fish), sharks are still refered to as 'fish' but biologically, they're just as different as the other classes. They just also happen to look kind of the same.

The same mistake is often made between reptile and amphibian, or aracnids and insects, etc.