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For anyone not reading the article, they close their gills to (we assume) not lose heat when they are diving in deep and cold water - very interesting - hadn't
by dmbche 3y ago
For anyone not reading the article, they close their gills to (we assume) not lose heat when they are diving in deep and cold water - very interesting - hadn't thought that gills are the fastest way to exchange heat for fish.
“Diving to over 1,000 metres from tropical temperatures at the surface down to just a couple of degrees centigrade to feed is a fairly extreme movement to do on a regular basis,” Simpfendorfer says.
!!
- kayodelycaon 3y agoIt makes a lot of sense when it's explained. Gills basically act like a heat exchanger for oxygen. Lungs work very differently. They don't have continuous flow and humans have mechanisms to heat up and moisturize air before it reaches their lungs.
- wil421 3y agoSalmon sharks are warm blooded and can stand temps down to about 36 degrees. I wonder if they have any adaptations in their gills to prevent heat loss or if they don’t care because they warm their bodies.
- dotancohen 3y agoDown to? That only a single degree below human body temperature.
- dmbche 3y agoI think they might be talking farenheits
- syockit 3y agoWhat I like about having an input method editor (IME) is that I can easily type units like ℃ or ℉ to avoid ambiguity. For a Japanese IME, just type ど (do, for degree), press spacebar until it pops out a conversion candidate list, then just find the symbol you want. Of course, you need to have known that the symbol appears ℉ when you type ど. There isn't an obvious way to find out which word is mapped to which symbol. Usually, I type きごう (kigou, for symbol) to get a list of symbols but ℉ does not appear in that list. Or, you can also use WinCompose (or Xcompose for X Windows users. For tty users, tough luck). At least, on my installation, it can be typed as "Compose Compose d e g f".
- rhn_mk1 3y ago"Compose o o" "C" °C
- samstave 3y agoThey move heat via blood into their bones such that their bones sheild the heat and can be re-pumpted back into the muscles over time to allow for deep divings.
- xattt 3y agoI have a crazy suspicion this mechanism is a thing in humans. After cold weather sets in the fall, it takes me a day or two before I start to be bothered by the chill. Mid-winter, I start to crave saunas. My assumption is the skeleton, marrow and body fat (or some other body structure with high thermal mass) act as a heatsink that expels some built up heat.
- samstave 3y agoMaybe this is where "I can feel it in my bones" comes in
- dotancohen 3y agoBones? I thought that sharks have no bones.
- samstave 3y agoI wonder if cartilege vs bones are a better heat / oxygen moderating permeable filter/exchanger, thus no bones....
- samstave 3y agoOK this is going to be a crazy post, just hold your horses cartelige is a permeable material for various occupants, oxigen being one. So we find that highly oxigenated creatures are larger and more carnivorous we also know that high ingestion of oxygen results in larger creatures so if a shark has a larger ability to permeate oxygen into the muscles and have the ability to store heat, plus the ability to transfer heat/oxy btwn bodies... This is why we can see a body +500 years old.. buoyed by the buoyancy of less dense bones, such as cartilage.
- conradev 3y agoNot quite warm blooded: > It is known for its ability to maintain stomach temperature (homeothermy), which is unusual among fish. This shark has not been demonstrated to maintain a constant body temperature. https://en.wikipedia.org/wiki/Salmon_shark https://en.wikipedia.org/wiki/Salmon_shark But there is indeed a vascular heat exchanger involved: https://en.wikipedia.org/wiki/Rete_mirabile https://en.wikipedia.org/wiki/Rete_mirabile
- dendrite9 3y agoI have wondered about bird ability to keep their feet in cold water, but not enough to look up how they've adapted. Thanks for that second link.
- wil421 3y agoYea I could link to two different sources who say endothermic, one of which is a university. The others are articles with spelling and grammar mistakes and that’s why I didn’t link a source. The shark can raise its body temperature 14-20 degrees more than the environment. I think it fits the definition of warm blooded. https://en.m.wikipedia.org/wiki/Warm-blooded https://en.m.wikipedia.org/wiki/Warm-blooded
- samstave 3y agoWim Hof would like a word. I used to be able to do homethermy by thought when I was younger... but I have lost the ability. (SERIOUS); I used to be able to direct heat to various extremities by thought when I was laying in bed in really cold environs... but I seem to have lost that ability.
- soperj 3y ago> Lungs work very differently. They don't have continuous flow I was under the impression that bird lungs do have continuous flow.
- reubenswartz 3y agoWater is a much more efficient heat exchanger than air.
- wil421 3y ago> The mammalian lung has reciprocating ventilation with large terminal air spaces (alveoli) while the avian lung has a flow-through system with small air capillaries. As a result the environment of the pulmonary capillaries is very different between the mammals and birds.[1] [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2681264/#:~:text=The%20mammalian%20lung%20has%20reciprocating,between%20the%20mammals%20and%20birds https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2681264/#:~:tex....
- pfdietz 3y agoThe way a paleontologist can tell if an animal was warm blooded is to look for the structures (basically an energy recovery ventilator, but made of bone) in the animal's airways. In mammals, it's in the nasal passages.
- codethief 3y agoI knew that breathing through the nose heats up the air before it hits the lungs but the energy recovery aspect is news to me. How does that work? Do we have a heat pump in our noses?
- nine_k 3y agoThink of the nose tissues as of a simple heat reservoir. When we inhale cold air, these structures warm it, and thus become colder. When we exhale hot air, it heats these structures, making them warmer again, to allow heating the next breath in. It's of course not 100% efficient, but it's better than nothing. I wonder uf there are more advanced strictures, like circulating liquid, to improve efficiency.
- codethief 3y ago> When we inhale cold air, these structures warm it, and thus become colder. When we exhale hot air, it heats these structures, making them warmer again How so? When you breathe in, your nose tissues will cool down to a temperature T_N and the air you inhale will heat up to a temperature T_A. Physics (the second law of thermodynamics) dictates that T_N >= T_A. Moreover, the nose tissues are connected to a large heat reservoir (the body), so we might as well assume they go back up to body temperature very quickly, so T_N = 37°C after a second or two. Either way, when you breathe out you still have T_N >= T_A. In this situation, there is no way the air could transfer back heat to the nose without a violation of the second law or, well, a heat pump. Hence my question.
- pfdietz 3y agoThe key point is that the temperature varies across the nose tissues. Close to the outside, it's low; farther in, it's high.