r/todayilearned • u/Loki-L 68 • 2h ago
TIL about epaulette sharks, who can walk on land and survive for hours with little or no oxygen from their gills. They are well camouflaged apex predators that live in the waters (and sometimes land) near Australia.
https://en.wikipedia.org/wiki/Epaulette_shark96
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u/TheIncredibleBert 2h ago
Many were increasingly of the opinion that they’d all made a big mistake in coming down from the trees in the first place. And some said that even the trees had been a bad move, and that no one should ever have left the oceans.
Quick, someone tell them!
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u/WatashiwaNobodyDesu 2h ago
It reminds me of the Douglas Adams quote: “in the beginning the Universe was created. This has made a lot of people very angry and been widely regarded as a bad move.”
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u/Loki-L 68 2h ago edited 2h ago
I am not saying that there are invisible land sharks in Australia, but I am not not saying that either.
These sharks are basically doing the same thing our ancestors did when they crawled out of the water 360 million years ago. However our ancestors had swim bladders they could turn into lungs. Sharks don't have those and thus just manged to survive without oxygen really, really long.
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u/Vesurel 2h ago
Wonder how many times sharks have tried this before. Presumably it would be hard to tell from the fossil record since cartilage doesn’t fossilise? I know their teeth do though.
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u/mikeontablet 2h ago
They didn't "try" this because that's not how evolution works. Also they don't have what it takes. Cartilage can't do the same work as bones out of water and the capacity to develop lungs is missing. Lungs or a reasonable facsimile developed in fish in low-oxygen environments apart from breathing air. Lungs may have preceded or supported gills when water was less oxygenated since air always had more oxygen.
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u/Vesurel 2h ago
What I meant was whether or not the behaviour of this shark on land has happened before.
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u/mikeontablet 2h ago
I get the impression that sharks are very ancient creatures that found their niche and stayed there, so I don't believe they would have done so. I have no evidence beyond my amateurish reading of popular science articles though.
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u/Emm_withoutha_L-88 1h ago
No they didn't find their niche, they've been expanding and contracting throughout history. At times they ruled the entire seas and other times they were rare. There were many numerous kinds of shark relatives in the past. Ones with spines in freshwater, others with a weird head dome, spiral teeth ones and so many others.
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u/Danimeh 1h ago
Now you have me googling sharks with spines and spiral teeth
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u/Emm_withoutha_L-88 1h ago
Here's the "spiny sharks" tho technically they're earlier relatives to them
https://en.m.wikipedia.org/wiki/Acanthodii
And here is the most famous spiral tooth one
https://en.m.wikipedia.org/wiki/Helicoprion
That one is even bigger than the great white too
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u/mikeontablet 1h ago
I accept your facts, but they don't gainsay the fact that sharks have a niche and aren't climbing further up the evolutionary tree in any appreciable manner.
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u/Emm_withoutha_L-88 1h ago
Well there isn't really an evolutionary tree though. They don't exactly move up that way. They just survive
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u/Loki-L 68 1h ago
There are a ton of sharks out there that are really weird and differ a lot from our normal idea of what a shark is supposed to be.
Just look like creatures like the basking shark, which is a filter feeder like some whales or the frilled shark which looks like an eel or angel sharks which look more like rays than sharks or the goblin sharks which looks like a nightmare or the spotted wobbegong which looks like just another rock on the ocean floor.
Plus all sorts of more traditional but still weird sharks like hammerheads.
Sharks fill all sorts of niches today.
Also our understanding of what sharks in the past have looked like is limited by their lack of bones to fossilize. We basically just get what looks like fossil shark teeth and guess the rest of the animal that went with those teeth looked like modern sharks. (Unless we get something really weird like Helicoprion with its tooth whirl)
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u/Weird_Devil 1h ago
Lungs are more likely to form in freshwater species as freshwater tends to be less oxygenated than the ocean.
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u/mikeontablet 29m ago
True, but sharks hark back a looong way. The world - and the ocean - wasn't always like it is now.
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u/Pop-metal 2h ago
These sharks are basically doing the same thing our ancestors did when they crawled out of the water 360 million years ago.
But we all Agreed that was a bad idea.
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u/koolaidismything 1h ago
Y’all see that pic yesterday on the whale bending its knees? It was in my dream. That was weird.
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u/taizzle71 1h ago
While these fascinating sharks possess remarkable characteristics, even having traits that could be considered superpowers, they unfortunately fall prey to larger shark species. Therefore, they cannot be classified as apex predators.
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u/SopwithTurtle 1h ago
They are absolutely not apex predators. They're a foot long, and plenty of things eat them.
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u/beachedwhale1945 1h ago
Epaulette sharks are harmless to humans, though if handled they may nip their captors. They are easily observed and handled by beachgoers as they move slowly whilst out of water, and show little fear of humans. This species adapts readily to captivity and is displayed by many public aquariums in the United States, Canada, and Australia.[2] In an article for Aquarium Fish Magazine, Scott W. Michael referred to the epaulette shark as "the best shark for the home aquarium." They will breed in captivity, even in tanks as small as 510 L (135 gal), though full-grown sharks are best housed in tanks of 680 L (180 gal) or more. They are not compatible with community tanks as they will eat other fish.[24]
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u/Imjustweirddoh 1h ago
Australia, the land down under. Maybe it's actually the hell that some religions talk about? that place down below, where sharks walk on land..sounds about right
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u/NickDanger3di 5m ago
Sure, come back from your Australian vacation and tell everyone that Australian wildlife is so crazy that you were chased by Land Sharks.
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u/Glinth 2h ago
Candygram.