MLP Theory Ep.3 repost: Seaponies are a myth. · 2:05am Jan 23rd, 2022
Supposedly, there is a race of ponies that live underwater. This is a myth.
Seaponies are supposed to be ponies that have a fish tail instead of hind legs. Surprisingly, aquatic animals have evolved from land mammals on Earth before. Seals and sea lions are part of the Caniformia suborder, the suborder that includes dogs and bears. Whales and dolphins and part of the Artiodactyla order, the order that also includes deer and pigs.
Perissodactyla, the order that ponies and rhinos are part of, is a sister clade to the Artiodactyla order. Hopefully you know what whales are.
If you look at a picture of a seapony, they do not appear to have gills. This is a problem, because they also do not appear to have to go to the surface of the water to breathe, like whales and dolphins. Near the sea floor on Earth, the percentage of free oxygen molecules is about 0.0002%. The air of earth is about 21% oxygen. Those snouts are nowhere near large enough to cycle enough water to fulfill their oxygen needs if the sea water in Equestria is similar to the sea water on Earth. Fish are a lot smaller than the size seaponies are supposed to be. Fish need to pump massive amounts of water through their gills.
Seaponies are also said to be able to speak underwater. Try sticking your snout in a large jar of water. Then try to say something. Even if you could speak underwater, the water would distort the sounds you make until they are illegible.
If you don't believe me, you can try going to Seaquestria and check. Someone built a train station near the coast there after all! Oh wait.... you can't breathe underwater to check. Isn't that convenient?
We don't know that for sure. The phylogeny of Laurasiatheria is still messy, but Perissodactyla and Cetartiodactyla (a new name acknowledging that Cetacea are a part of Artiodactyla as a sister clade of Hippopotamidae) don't appear to be sister clades in many analyses.
Assuming you'd be able to see external gills. That may not be the case, many animals that live in water may utilise other body parts for breathing, oftentimes including the anal area of their gut, e.g. dragonfly larvae, turtles. (Breathing oxygenated perfluorocarbon through the gut was also demonstrated in certain mammals and is debated as a potential way of ventilation in human medicine. A layperson-friendly article here.) Coupled with protenis with sufficiently high affinity for oxygen, specific regulations of metabolism, et cetera, they could technically survive. If they do breathe air, similar adaptations could help the seaponies stay underwater for a long while with them just occasionally having to go the the surface or some air-filled cavity.
Fish are a lot smaller? Many fish are, especially the ones people are usually familiar with, but many fish are also pretty huge. See beluga sturgeon (Huso huso), giant oarfish (Regalecus glesne), opah (Lampris guttatus), marlin (genus Makaira, for example), alligator gar (Atractosteus spatula), Arapaima, ocean sunfish (Mola mola), and even something so common as a bluefin tuna (Thunnus thynnus). These are just a few examples of many, I didn't even delve into Chondrichthyes. (Which are not considered to be fish in some other languages.)
This is a bit of a misleading statement. We also need to pump massive amounts of air into are lungs. Fish are actually far more effective than us, many of them utilise the same pumping for filter-feeding. For example, anchovy swim with their mouths open, filtering both oxygen and food from the resulting water current:
imgs.mongabay.com/wp-content/uploads/sites/20/2017/11/29110031/anchovy-close-768x512.jpg
Also, note that sequestering dissolved oxygen from water and from air requires different mechanisms, so comparing the percentages and such doesn't work well. The partial pressure of oxygen in water also varies a fair bit.
Agreed with this one, though, you know, there's always magic... After all, pegasi shouldn't be able to fly, but they do. So, yes, seaponies as depicted are a myth, and so are many other Equestrian creatures.
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These are supposed to be like conspiracy theories, and I know nothing about biology, so I'm sorry this isn't exactly correct.
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Heh, I see. I hope you don't mind that I decided to chime in.
And despite knowing nothing about biology, you came pretty close to the truth. (Or what modern science deems to be the truth, anyway.)
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I sourced most of my data from Wikipedia.
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Understood. It's good to always check if the data are sourced and if yes, if the sources seem to be relevant and up-to-date. Also, you may find Google Scholar a very helpful tool.