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Jupiter60
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Why haven't whales evolved gills?
Jupiter60 said:Why haven't whales evolved gills?
Whales evolved from gilled predecessors; should there be any advantage to devolving?Jupiter60 said:Why haven't whales evolved gills?
Do you have a reference for this?Bystander said:Whales evolved from gilled predecessors; should there be any advantage to devolving?
None? https://en.wikipedia.org/wiki/Vertebrate_Paleontology_and_EvolutionSteamKing said:no creatures with gills in their family tree.
SteamKing said:Do you have a reference for this?
Cetaceans are thought to have evolved from terrestrial mammals, and early whale ancestors are presently thought to be distantly related to modern-day hippos.
https://en.wikipedia.org/wiki/Evolution_of_cetaceans
As terrestrial mammals, there would have been no creatures with gills in their family tree.
I'm talking about in relatively recent times geologically speaking.Bystander said:
There are similar structures on the vertebrae of many mammals, including humans:Bystander said:
Bystander said:should there be any advantage to devolving?
We're agreed.SteamKing said:but that doesn't mean that humans necessarily will form spores and hibernate like bacteria do.
(Picture of one of my "funny cousins.")SteamKing said:Dimetrodon is also thought to be distantly related to the ancestors of mammals,
http://people.eku.edu/ritchisong/342notes2.htmSteamKing said:This doesn't mean that human ancestors had sails popping out of their backs.
Ygggdrasil said:Apparently, breathing air with lungs enables much higher rates of oxygen exchange than breathing water with gills, which allows whales and other marine mammals to have higher metabolic rates than fishes:
cosmik debris said:so evolving gills would be a backward step.
Jupiter60 said:I would think that because whales are aquatic animals having gills would be an advantage.
Alcathous said:A lot of what people are saying here is wrong or unsubstantiated. This is all quite difficult to figure out.
Alcathous said:Can gills evolve into lungs but not lungs into gills?
Alcathous said:Also, having gills doesn't mean you can't have lungs.
As long as whales are warm blooded, gills will be incompatible with their make up.Jupiter60 said:Why haven't whales evolved gills?
johnnymorales said:It took millions of years more before a creature developed lungs so efficient they could dispense with gills. In the interim many had both lungs and gills, and some amphibians still have that set up.
Thanks. About the only thing I would take issue with is your use of the word parsimonious. I'm sure I get your point, but only by extrapolation.DiracPool said:I like your post, and I kind of anticipated your quote above, especially in the transitory amphibians, which is why I revised my statement in my earlier post to ,"especially in larger aquatic mammals." However, I defend my position that evolution is parsimonious. But in the transitionary phases, if a trait or a redundancy does not negatively affect selection it does stand a chance of persisting, as in the amphibian cases you mentioned. Although, for the record, I have not researched this so I'm taking johnny's word here for the meantime.
johnnymorales said:About the only thing I would take issue with is your use of the word parsimonious
DiracPool said:That's about the only thing you shouldn't take issue with. As sure as natural selection, evolution is built on parsimony. Do you disagree with this?
If evolution is parsimonious, why do we have vestigial structures like a tailbone or an appendix? Why is about half of the human genome composed of repetitive sequences that are derived from viruses or mobile genetic elements? I get your general point and agree that an organism with both lungs and gills would likely vestigialize one of the organs if it used only one (it is much easier for random mutation to degrade unecessary function), but I'd disagree with the general statement that evolution is parsimonious.DiracPool said:That's about the only thing you shouldn't take issue with. As sure as natural selection, evolution is built on parsimony. Do you disagree with this?
I also disagree that usage of the word parsimony is tied to money. The http://dictionary.reference.com/browse/law+of+parsimony, commonly referred to as https://en.wikipedia.org/wiki/Occam's_razor]Occam's[/PLAIN] [Broken] razor or lex parsimoniae, is very often cited in many fields of science, including evolutionary biology.johnnymorales said:Parsimony is NOT a general use word.
Ygggdrasil said:If evolution is parsimonious, why do we have vestigial structures like a tailbone or an appendix? Why is about half of the human genome composed of repetitive sequences that are derived from viruses or mobile genetic elements?
Chronos said:Environmental factors probably favored their return to aquatic dwelling as a survival response.
DiracPool said:If it takes more energy to remove the structure than it does just to ignore it, evolution is just going to ignore it. This goes the same for the genome
DiracPool said:What's your evidence for this? I see none. It doesn't have to be an environmental driver that pushed them back into the sea. Maybe they just tired of competing with the other land mammals and said I'm going to jump into the water and see what's down there.
Pythagorean said:That would be an envrionmental driver, no?
good question, ignore the ignorani that question your motive.Jupiter60 said:Why haven't whales evolved gills?
Evolving gills would not be a backward step. For a whale to evolve gills would be an absolutely huge step forward. Evolution doesn't take giant steps. It can't. Most evolutionary steps are little tiny baby steps. Every once in a while, evolution takes a bigger stride. But unlike Superman, it never, ever leaps across the Grand Canyon in a single bound.Fernando L. said:Evolving gills would be a backwards step and requires too many structural changes in the body and its design.
Whales are mammals and are adapted to live in water but breathe air. They have evolved a specialized respiratory system that allows them to hold their breath for long periods of time while diving. This system is more efficient for their large body size and energy needs compared to gills.
No, whales cannot breathe underwater like fish with gills. They must come to the surface to take in air through their blowhole, which is connected to their respiratory system.
It is believed that the ancestors of whales did have gills and lived in the water. However, as they evolved and adapted to life in the ocean, their respiratory system changed to better suit their needs.
Dolphins are not true gills, but rather specialized structures called "baleen plates" that are used for filter-feeding. They are not used for respiration like gills in fish.
It is highly unlikely that whales will evolve gills in the future. Evolution occurs through natural selection and the current respiratory system of whales is well-suited for their environment and way of life. It is more likely that they will continue to adapt and evolve within their existing respiratory system.