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olePigeon · Oct 31, 2005, 11:20 AM

http://www.nsf.gov/news/news_summ.js...&from=news

Some nifty discoveries about some species of tuna and sharks; in particular, the salmon shark. It would appear that they're homeothermic (or warm-blooded) and can control their body temperature.

I find this particularly interesting because it would appear that dinosaurs varied greatly in terms of their body temperature (we can hypthosize whether or not they had endo- or ectothermic temperatures from the fossilized soft tissues of newborn dinosaurs.) But what was weird was that some closely related dinosaurs that you'd think would either both be warm-blooded or both be cold-blooded, weren't. One species would appear to be cold-blooded while a related species appeared to be warm-blooded.

Well, now we have direct evidence that this occurs even in today's species. So it's not far fetched to assume that dinosaurs may evolve the same way, even within closely related species.

jcadam · Oct 31, 2005, 12:11 PM

I once worked for a cold-blooded, conniving b!tch of a human being.

El Gato · Oct 31, 2005, 12:23 PM

Originally Posted by jcadam

I once worked for a cold-blooded, conniving b!tch of a human being.

Was she hot?

jcadam · Oct 31, 2005, 12:29 PM

No. She was Korean, was too well built for a woman, and walked like a man. And cursed at you in Korean. And didn't shower all the time.

El Gato · Oct 31, 2005, 01:01 PM

When she finished cursing at you, you should have said "oooooooh, machi-soyo! igoto zhum-che-se-leyo."

The extent of my Korean is ordering in a restaurant, but I think it fits pretty well.

isao bered · Oct 31, 2005, 03:01 PM

Originally Posted by jcadam

And didn't shower all the time.

?! if she *did* shower *all* the time it would be hard to keep a job. do you mean she showered infrequently? ;-)

sorry. sometimes i just can't help myself. :-)

be well.

laeth

ASIMO · Oct 31, 2005, 03:16 PM

Originally Posted by jcadam

I once worked for a cold-blooded, conniving b!tch of a human being.

I think I know what you mean. Family businesses can sometimes be difficult.

isao bered · Oct 31, 2005, 03:21 PM

Originally Posted by olePigeon

Some nifty discoveries about some species of tuna and sharks; in particular, the salmon shark. It would appear that they're homeothermic (or warm-blooded) and can control their body temperature.

the article didn't seem to intimate that there was a metabolic functions working to keep a near-constant body temperature. it seemed to indicate that the location of the muscle combined with the shark having to constantly swim (to not sink) acted to warm the entire body. would this still fit the conventional understanding of "warm-blooded"?

nevertheless, it's still interesting to find an explanation of how a creature that at first would seem an unlikely candidate to survive an environment actually thrives. though i am unsure from the article how exactly the red muscle location in a tuna shark will lead to better designs for undersea vehicles... ??!

National Science Foundation (NSF) program manager, Ione Hunt von Herbing said, "Knowing specific details about the anatomy and physiology of salmon sharks provides key insight into their ability to produce such power and speed during swimming. The knowledge could translate into better designs for underwater vehicles."

be well.

laeth

olePigeon · Oct 31, 2005, 03:57 PM

Originally Posted by isao bered

the article didn't seem to intimate that there was a metabolic functions working to keep a near-constant body temperature. it seemed to indicate that the location of the muscle combined with the shark having to constantly swim (to not sink) acted to warm the entire body. would this still fit the conventional understanding of "warm-blooded"?

Warm-blooded, yes, but not tachymetabolic. It's a different process to achieve the same result. Instead of controlling metabolism based on the temperature, the shark has (what I can only guess) a central "heater" muscle. By using that muscle, it maintains a constant temperature.

I think that's part of the reason why "warm-blooded" isn't used very often because some "cold-blooded" animals (like this shark and the tuna mentioned) would fall under both categories.

However, I think it's fascinating because between two very similar species of fish, one devloped a great way to function in frigid waters. This is similar to many dinosaurs as I mentioned before.

Originally Posted by isao bered

nevertheless, it's still interesting to find an explanation of how a creature that at first would seem an unlikely candidate to survive an environment actually thrives. though i am unsure from the article how exactly the red muscle location in a tuna shark will lead to better designs for undersea vehicles... ??!

Do warmer bodies move more efficiently through cold water? Can a well placed "heater" in a submersible tied in with some sort of flexible membrane allow for an efficient, endothermic based propulsion? Sure as hell beats me. Anyone else care to comment?

rambo47 · Oct 31, 2005, 04:05 PM

I recall reading somewhere that the Great White shark was partially warm-blooded. The theory was that this partial warm-bloodedness was partly responsible for it's aggressiveness.

isao bered · Oct 31, 2005, 07:31 PM

Originally Posted by olePigeon

By using that muscle, it maintains a constant temperature.

that's what i wasn't clear on when reading the article. if the heat generated by the muscle kept their temperature constant or just warmed them - that their body temperature might actually fluctuate with the temperature of the water. so if they moved from 54° to 50° would we expect to see a corresponding decrease in body temperature? they gave quite a generous temperature range for the muscle and i couldn't determine if that was a direct reflection of water temps they could withstand.

Originally Posted by olePigeon

However, I think it's fascinating because between two very similar species of fish, one devloped a great way to function in frigid waters. This is similar to many dinosaurs as I mentioned before.

:-) i think i was looking at it the other way - how cool it was that a muscle apparently developed to help them stay in motion (so they wouldn't sink) had the additional benefit of allowing them to hunt in cooler waters.

be well.

laeth

bad_quote · Oct 31, 2005, 07:58 PM

Boy, the Lord sure goes to extrordinary lengths to decieve us, doesn't he?

isao bered · Oct 31, 2005, 08:22 PM

Originally Posted by bad_quote

Boy, the Lord sure goes to extrordinary lengths to decieve us, doesn't he?

i'm probably going to regret this. especially since the pigeon gets upset when his science posts are derailed by religion.

an opposing view (paraphrase): "it is the glory of a king to conceal a matter. it is the glory of man to search it out." science is a man thing.

and for the catholics, perhaps i'll now self-impose a penance upon me. 24-7 of 23:9. :-)

apologies pigeon.

be well.

laeth