Warm blooded vs. cold blooded animals: accounting for the difference

I know “warm blooded” and “cold blooded” have fallen out of favour with biologists, but it remains true that certain animals must bask in the sun to warm up their bodies, in contrast to others (humans included) that produce their own heat.

However, my understanding of human anatomy is that this latent heat is generated by the burning of “fuel” in individual cells within the body. So, what accounts for the difference in cold blooded animals? Is there a different cell structure, or what? What factors, biologically, make a certain animal warm or cold blooded?

Slight tangent: this question also reminded me of a question I’ve never been able to really answer.

Why the terms ‘warmblood’ and ‘coldblood’ for horses? :confused: Wikipedia just says that these are classifications for various breeds, but doesn’t seem to say why they’re called that.

This will probably be an inadequate answer. But some animals (endotherms) maintain a relatively constant body temperature because they “burn”–i.e., oxydize–fuel internally. As endotherms metabolize nutrients, and perform respiration, a byproduct of that oxidation is heat. It’s my understanding that the majority of nutrients used by endotherms goes specifically to keeping this “furnace” burning. Ectotherms, on the other hand, are able to get by on far smaller amounts of nutrients, because rather than stoking their inner fires, they absorb heat from external sources; ambient, radiant, and conductive, IIRC. Obviously there are evolutionary pros and cons to both systems, which is why both have proved successful.

I don’t know the answer to the OP, but I can help with this one.

“Hotblood” horses were originally the oriental desert breeds - basically the Arabian and the Barb. They tend to be fairly light and fast horses with lots of stamina. They also tend to be temperamental and skittish, i.e., “hotblooded”. (When the English Thoroughbred breed was being developed, it had so much Arab and Barb crossed in that it is also considered a hotblooded breed.)

All the other horses (back then) were called “coldblood”. You’re mostly talking ponies, draft and farm horses, etc. They tended to be stouter and calmer breeds.

Warmbloods were originally cold/hot mixes bred to combine the best traits of both groups - to join the elegant, slender lines, speed, and energy of the hotbloods with the stronger legs and build and calm temperament of the coldbloods. As happens with these things, the original mixes became recognized Warmblood breeds.

A question I have concerning fish There are tropical fish, that die in cold water; Cold water fish that survive as long as the water doesn’t freeze, and Koi seem to croak somewhere in between.

Oooh. Thanks for this explanation! My ignorance has been fought.

Again, oversimplifying: we are made of water, because we came from water. What made it possible for us to leave the water was that we developed a way (oversimplifying) to carry a self-contained “ocean” around with us: our circulatory system. Warmblooded animals developed a pretty sophisticated self-regulating internal pumping system to keep oxygen and nutrients supplied to each cell in our bodies, while many the smallest of the oceanliving animals have enough of their cells within direct proximity to the actual ocean (as opposed to our “artificial” one) that they can collect what they need directly through osmosis.

Now, the ocean is extremely stable, certainly as compared to a single land dwelling animal’s body; it can take decades to vary by a fraction of a degree, or minute changes in chemistry. So animals who “stayed behind” didn’t necessarily need to evolve the kind of self-regulating systems that we did; the system they live in doesn’t really require regulation because it’s so very very stable.

This is a complicated (yet still vastly oversimplified) explanation to explain the different degrees to which animals are dependent upon the stability of their environment for survival. Fish are separated from the larger circulatory system of the body of water they live in only by an osmotic membrane, so fish that live in extremely stable systems can be drastically affected by minute changes in the water, chemically or temperature-wise. So, with many exceptions of course, many species of fish tend to live in a relatively narrow window of tolerance. So fish that have evolved in warm water tend not to adapt favorably in cold, and vice versa. Fish that evolved in ecosystems that change rapidly–mountain streams; tide pools; rainy-season waterholes–tend, of course, to have higher tolerances for sudden changes.

Dammit, they’re fish. Mammals don’t have this problem. Polar bears have hair. Penguins…well, I don’t know about penguins.

How does this explain coldblooded lizards who live in the desert miles away from any ocean?

The desert is low on resources; reptiles don’t need as many resources as mammals, since they don’t burn energy just to maintain body heat, nor do they need to breathe as much ( which helps them avoid water loss from evaporation ). Therefore, you tend to find more reptiles in places like deserts or small islands, where food or water is scarce, but the temperature is survivable for coldblooded reptiles.

Sure, that’s the obvious answer that makes sense. I’m asking lissener how his “portable ocean” explanation accounts for cold blooded animals in the desert and warm blooded animals living in the ocean.

Staff Report: What makes some animals cold-blooded and others warm-blooded

I think that he was answering the question about why tropical fish can’t tolerate temperature changes, not the original hot blooded versus cold blooded question.

The warm blooded animals in the ocean came back from the land. And they are still a lot more isolated from the surrounding water than the fish, who actually breathe it. In fact, it’s unlikely that a warm blooded creature could survive as a water breather; water is a much better heat sink than air.

I remember reading a how stuff works article about why dolphins don’t evolve gills. IIRC air has 20x more breathable oxygen then water. So the answer was because warm blooded animals wouldn’t get enough oxygen to support their rapid body heating metabolisms with gills.
What about sharks though? I remember reading their bodies can do some temperature regulation and they sort of are warm blooded. Is their any truth to that? If so how do they manage in the water?

It doesn’t “account for” them at all. It wasn’t intended as a comprehensive theory for understanding all life on earth; it was just an illustration to try to explain the evolution of self regulating systems. While ectotherms are not internally regulated, they can be"self" regulated in that, for example a lizard, will find warm sunny spot (or a warm rock) to raise his body temperature to get his metabolism going. Again speaking vastly oversimplifi . . . cationally? or something . . . this would put ectotherms such as the exemplar lizard somewhere on the (imaginary) spectrum between a single-celled aquatic organism and, say, an Ice Age Mammoth. Self-regulating-wise.

Don’t warm blooded have some degrees? As well as cold blooded? In otherwords there may be variations or degrees in the way different animals maintain their warm bloodedness

Wait. Are you saying that Kevin Costner’s gills in Waterworld wouldn’t really have worked? Dammit, now I want my 8 bucks back!

All animals have different optimal body temperature ranges. Where the exact optimal point is varies by species and individual. This isn’t specifically from the leakiness of the mitochondiral electron transport chain, but from the bazillions of other chemical and biological reactions that make up living critters.

There’s been a fight in the scientific community lately to re-educate people on the whole cold-warm-blooded/endo-exothermic issue. Just like the futile attempts to rename jelly fish as “jellies” because they’re not fish.

The article you read was probably referring to the fact that some amount of body heat is generate from muscle exertion and digestion, and that the shark does use this to help keep some of it’s body functions running optimally.
Here’s an article, which also indicates that some species of tuna use the same tactic.

Ocean life is so incredibly diverse, if there’s a way of living it, there’s an ocean critter that does it.