Endothermic Reptiles?
- Thread starter yhelothar
- Start date
Siddhartha
Lifer
- Oct 17, 1999
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There was talk awhile back that some dinosaurs were at least functionally "warm blooded". I have not kept up on the subject so I can not say what the latest thought is on the subject.
- Dec 11, 2002
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Yeah that was part of my bio prof's argument.
He said that many argues that there is no such thing are reptiles.
Wikipedia seems to classify birds under the reptilia order.
Maybe birds are the warm-blooded reptiles?
http://en.wikipedia.org/wiki/Chordate
He said that many argues that there is no such thing are reptiles.
Wikipedia seems to classify birds under the reptilia order.
Maybe birds are the warm-blooded reptiles?
http://en.wikipedia.org/wiki/Chordate
- Dec 11, 2002
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My professor was arguing that birds are really just reptiles with feathers and were not classified as reptiles as they had novelties(feathers). Then I argued that birds aren't reptiles because they were endothermic. That's when my professor laughed at me and told me that I was very wrong.
Endothermy is a matter of degree, if you'll forgive the pun. Most mammals are fully endothermic, but other animals exhibit a degree of endothermy. Leatherback turtles and tuna, for example--if memory serves.
- Dec 11, 2002
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Yeah I read about the leatherback turtles in wikipedia. It says that they have a 20°F higher body temperature than their environment.
But that just means that they can make body heat, rather than have the organs that regulate body temperature at a constant level.
All mammals are fully endothermic, as are all birds. There are no degrees of endothermy - an organism is either an endotherm or it isn't. Endothermy's strict definition is an organism that devotes part of its metabolism to generating heat for the specific purpose of homeothermy - maintaining a relatively constant internal body temperature. Ectothermy is the opposite, an organism that devotes none of its metabolism to generating heat specifically for maintaining a constant internal body temperature.
Leatherback turtles, tuna, and various species of extinct reptiles (such as the really big monitor that used to live in Australia) are inertial homeotherms, or gigantotherms. Ectothermic organisms of sufficiently large body mass (or high enough body mass:surface area ratios, to be more specific) maintain a relatively constant internal temperature simply because they're really big, and they don't lose heat fast enough to have their internal temps in flux with the external environment.
In terms of classifying birds, the vernacular 'bird' isn't scientifically sound (it's a paraphyletic taxon) - birds technically are reptiles, at least if you call crocodiles and their kin reptiles. Birds & the crocodilians are more closely related to each other than either are to snakes, lizards, and turtles - this is confirmed by morphological, genetic & behavioral lines of evidence.
Ask your Professor what (s)he thinks about the argument that turtles aren't really reptiles.
By the way, what class is this, and where, if you don't mind me asking.
Leatherback turtles, tuna, and various species of extinct reptiles (such as the really big monitor that used to live in Australia) are inertial homeotherms, or gigantotherms. Ectothermic organisms of sufficiently large body mass (or high enough body mass:surface area ratios, to be more specific) maintain a relatively constant internal temperature simply because they're really big, and they don't lose heat fast enough to have their internal temps in flux with the external environment.
In terms of classifying birds, the vernacular 'bird' isn't scientifically sound (it's a paraphyletic taxon) - birds technically are reptiles, at least if you call crocodiles and their kin reptiles. Birds & the crocodilians are more closely related to each other than either are to snakes, lizards, and turtles - this is confirmed by morphological, genetic & behavioral lines of evidence.
Ask your Professor what (s)he thinks about the argument that turtles aren't really reptiles.
By the way, what class is this, and where, if you don't mind me asking.
shilala
Lifer
- Oct 5, 2004
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I'm glad you weighed in on this Gigantopithecus.
There's a moth that has such large wing muscles that it generates enough body heat to push it into a "gray area".
What species is it? Is there a scientific name for that?
I've kept birds for years. The initial attraction (from when I was a little kid) was the living dinosaur link.
I love watching them. They are so intelligent it's scary.
What "organs" are you thinking of? Heat can be generated through muscular contraction and other processes (uncoupling of oxidative phosphorylation comes to mind), but I'm not sure what would be a dedicated heat-producing organ unless you're thinking of brown fat.
Not all mammals are fully endothermic and regulate their body temperatures at a constant level, either--the echidna, for example, does regulate its body temperature somewhat, but the regulation is rather loose and its internal body temperature fluctuates widely depending on the temperature of its environment.
"Reptile" (if it excludes birds but includes crocodiles) is a paraphyletic taxon, but "bird" is not. At least I don't recall encountering any strong evidence for the non-monophyly of birds.
If you want to be really anal, there are plants that are endothermic. The eastern skunk cabbage (Symplocarpus foetidus) keeps the inside of its spathe right around 70F while it is blooming, even if there is snow on the ground, so early-waking flies will hang out there and polinate it.
That's very fascinating!
Do you know the mechanisms involved in creating the heat? Where does it come up with the energy?
Whoops! I misspoke. Good thing this isn't an exam, hehe.
You're confusing endothermy with homeothermy. Homeothermy comes in degrees (not all endotherms are equally good at keeping a constant internal temperature, and some ectotherms are), endothermy & ectothermy do not - an organism either devotes part of its metabolism specifically towards generating heat or it doesn't.
That said, neither endotherm nor ectotherm are really accurate terms (they're too vague, and there's too many unusual cases). It's better to use terms like brady- and tachymetabolic (low vs. high resting metabolism), colonially homeothermic (bee hives, termite mounds), heterothermic (homeothermic when active, poikilothermic when dormant, like microchiropterans, hummingbirds), etc. etc.
Interesting stuff.
I think you might be referring to the Atlas moth of Southeast Asia, that's the largest moth in the world. It might be an inertial homeotherm, though I'm skeptical because even though it's giant for an insect, it's still not very big compared to things like a leatherback turtle.
- Dec 11, 2002
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My professor actually said that there is biological trait that defines a reptile, thus many are arguing that there is no such thing as reptiles. But the reptile order is retained as no biologist has come up with a new way to classify them yet.
It's for a bio2 class, which is a second level biology class. First is biology for majors.
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