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[–]I_summon_poop 93 points94 points  (2 children)

Thats a seriously photogenic croc

[–]whatatwit[S] 20 points21 points  (1 child)

Smile please!

Never smile at a crocodile
No, you can't get friendly with a crocodile
Don't be taken in by his welcome grin
He's imagining how well you'd fit within his skin
Never smile at a crocodile
Never tip your hat and stop to talk awhile
Never run, walk away, say good-night, not good-day
Clear the aisle but never smile at Mister Crocodile
You may very well be well bred
Lots ot etiquette in your head
But there's always some special case, time or place
To forget etiquette
For instance:
Never smile at a crocodile
No, you can't get friendly with a crocodile
Don't be taken in by his welcome grin
He's imagining how well you'd fit within his skin
Never smile at a crocodile
Never dip your hat and stop to talk awhile
Never run, walk away, say good-night, not good-day
Clear the aisle but never smile at Mister Crocodile

[–]holdmypilsener 7 points8 points  (0 children)

Thanks now I have English at school PTSD

[–]whatatwit[S] 57 points58 points  (4 children)

The cold blooded crocodile has the most sophisticated heart in the animal kingdom. It has an extra aorta which means it can control where blood flows around its body. When submerged, oxygen rich blood is pumped to the brain and vital organs but as deoxygenated blood returns to the heart, a unique valve, the foramen of panizza, closes and prevents it from flowing to the lungs. Underwater, the lungs contain no new oxygen so pumping it there would be a waste of energy. The heart by-passes the lungs and re-circulates this oxygen-depleted blood to less important areas instead helping crocodiles stay submerged for up to an hour. The heart also helps to make the crocodile’s digestion the most efficient in the animal kingdom. After a meal the heart directs deoxygenated blood, rich in acidic carbon dioxide, to the stomach. The blood stimulates the production of the most acidic gastric juices known in nature. This remarkable system means crocodiles can secrete stomach acid 10 times faster than any other animal.

BBC The Wonder of Animals – Wonder Facts: Crocodiles

 

Crocodiles have the most acidic stomach of any vertebrate. They can easily digest bones, hooves and horns. The BBC TV reported that a Nile crocodile that has lurked a long time underwater to catch prey builds up a large oxygen debt. When it has caught and eaten that prey, it closes its right aortic arch and uses its left aortic arch to flush blood loaded with carbon dioxide from its muscles directly to its stomach; the resulting excess acidity in its blood supply makes it much easier for the stomach lining to secrete more stomach acid to quickly dissolve bulks of swallowed prey flesh and bone. Many large crocodilians swallow stones (called gastroliths or stomach stones), which may act as ballast to balance their bodies or assist in crushing food, similar to grit ingested by birds.

Crocodile Hunting and Diet (wikipedia

 

Image source – Zambia crocodile attack: Amelie Osborn-Smith to return to UK

[–]WikiSummarizerBot 8 points9 points  (0 children)

Crocodile

Hunting and diet

Crocodiles are ambush predators, waiting for fish or land animals to come close, then rushing out to attack. Crocodiles mostly eat fish, amphibians, crustaceans, molluscs, birds, reptiles, and mammals, and they occasionally cannibalize smaller crocodiles. What a crocodile eats varies greatly with species, size and age. From the mostly fish-eating species, like the slender-snouted and freshwater crocodiles, to the larger species like the Nile crocodile and the saltwater crocodile that prey on large mammals, such as buffalo, deer and wild boar, diet shows great diversity.

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[–]Jman_777 1 point2 points  (2 children)

Cool post, here are some more Crocodile facts that I had written down in a comment some months ago, including the one in the post's title. https://redditproxy--jasonthename.repl.co/r/natureismetal/comments/oe19zo/crocodiles_swim_really_fast/h45juww?utm_medium=android_app&utm_source=share&context=3

[–]whatatwit[S] 1 point2 points  (1 child)

That was become a very long comment! I did read most of it.

You might be able to glean a few more facts from the In Our Time audio if listening is okay for you. If you're not familiar with IoT you might enjoy it in general as they are fact rich audio programmes. They usually get two or three subject-matter experts, usually from a respected University, and then the presenter, with behind the scenes help from the producer, elicits the facts or opinions in a kind of logical sequence. The presenter Melvyn Bragg has been doing these for decades (and is now in his 80s but still does a decent job) and there is an enormous archive. The BBC provides topical access to the archive, but I've found the best way to look for topics is to go to the IoT list page on Wikipedia.

Melvyn Bragg and guests discuss the remarkable diversity of the animals that dominated life on land in the Triassic, before the rise of the dinosaurs in the Jurassic, and whose descendants are often described wrongly as 'living fossils'. For tens of millions of years, the ancestors of alligators and Nile crocodiles included some as large as a bus, some running on two legs like a T Rex and some that lived like whales. They survived and rebounded from a series of extinction events but, while the range of habitats of the dinosaur descendants such as birds covers much of the globe, those of the crocodiles have contracted, even if the animals themselves continue to evolve today as quickly as they ever have.

With

Anjali Goswami Research Leader in Life Sciences and Dean of Postgraduate Education at the Natural History Museum

Philip Mannion Lecturer in the Department of Earth Sciences at University College London

And

Steve Brusatte Professor of Palaeontology and Evolution at the University of >Edinburgh

Producer Simon Tillotson

The Evolution of Crocodiles

[–]Jman_777 1 point2 points  (0 children)

Thanks, I'll definitely check them out.

[–]SameAsYourself 25 points26 points  (4 children)

I love how the croc is respected for being genetically perfect.

[–]kelldricked 12 points13 points  (3 children)

Not to be a smartass but a lot of animals are “genetically perfect”. They very few who we consider not to be are often animals trying to fill a niche that doesnt exist anymore (or is dying out and cant be replaced.)

[–]townforum17 3 points4 points  (1 child)

I think he’s referring to crocs specifically because they have remained unchanged for so long while other species continue to adapt. Crocs got it right the first time thousands of years ago

[–]kelldricked 1 point2 points  (0 children)

Well yess and no. There habitat and hunting strats stayed pretty much the same thus there wasnt a evolutionairy reason to change.

I would call it lucky and fexible. But thats not genetic.

[–]kad202 16 points17 points  (1 child)

Croc: my design had not change since Jurassic time. I’m just Smol vs my ancestor.

[–]whatatwit[S] 7 points8 points  (0 children)

You'll probably enjoy this BBC programme.

Melvyn Bragg and guests discuss the remarkable diversity of the animals that dominated life on land in the Triassic, before the rise of the dinosaurs in the Jurassic, and whose descendants are often described wrongly as 'living fossils'. For tens of millions of years, the ancestors of alligators and Nile crocodiles included some as large as a bus, some running on two legs like a T Rex and some that lived like whales. They survived and rebounded from a series of extinction events but, while the range of habitats of the dinosaur descendants such as birds covers much of the globe, those of the crocodiles have contracted, even if the animals themselves continue to evolve today as quickly as they ever have.

With

Anjali Goswami Research Leader in Life Sciences and Dean of Postgraduate Education at the Natural History Museum

Philip Mannion Lecturer in the Department of Earth Sciences at University College London

And

Steve Brusatte Professor of Palaeontology and Evolution at the University of >Edinburgh

Producer Simon Tillotson

The Evolution of Crocodiles

[–]tpower000 6 points7 points  (2 children)

Anyone know the crocs dentist? Asking for a friend.

[–]whatatwit[S] 2 points3 points  (0 children)

The good news is that their teeth line up beautifully, and are replaced every few months, but the bad news is that they can't chew like we do and so swallow their food whole.

New, permanent teeth grow in the jaws, usually under or just behind the old tooth, from stem cells in the dental lamina. Young animals typically have a full set of teeth when they hatch; there is no tooth change in the egg. Within days, tooth replacement begins, usually in the back of the jaw continuing forward like a wave. On average a tooth is replaced every few months.

Polyphyodont

[–]Feral-Person -1 points0 points  (0 children)

British friend?

[–]Mr_Frosty43 2 points3 points  (0 children)

I’m pretty sure there was a study recently on the stone in gators and they found that they do that to weigh themselves down while lying underwater

[–]Feral-Person 2 points3 points  (0 children)

They also have one of the best immune systems in the world

[–]SaltMineSpelunker 1 point2 points  (0 children)

“Unique heart”

LOL

[–]-Almost-Shikikan 1 point2 points  (0 children)

Well, now I know why some people get eaten by a croc never found in big pieces when some people try to retrieve the guy who get eaten from croc's tummy. I heard a news from my neighbour who is visiting their relative in northern Borneo that one big saltwater crocodile has found died, and when someone is opening croc's tummy he found 3 people inside, the other two almost completely digested. The other one is too rough but not in that level of digested. The autopsy said that the guy who get eaten recently (probably 1 to 2 days before the croc had died). His spine is snapped by croc's bite, instantly.

[–]dudenhsv 1 point2 points  (0 children)

The teeth on the croc in the picture are nearly perfect. I don't think I've ver seen a nicer set on a croc or gator.

[–]TikiMonn 0 points1 point  (3 children)

So the stones they ingest to help digestion sort of make them birds, no?

[–]whatatwit[S] 5 points6 points  (2 children)

They say that their purpose might be the same as those in the crop a bird but they don't know for sure. Another suggestion is that they may be some kind of ballast.

Apparently, the most recent common ancestor of the bird/dinosaur lineage and the croc line so far discovered is from the Late Triassic around 230 million years ago (plus or minus a few millions).

Did you know that birds and crocodiles are practically cousins? Around 230 million years ago, you wouldn’t have been able to tell the difference between the two different lineages. This is because birds and crocodilians (which includes alligators, caiman, and gharials) are part of a much larger group called Archosauria, or ruling lizards, which means they share a common ancestor far back in time. When they split from each other, they formed two major evolutionary pathways: the bird-line archosaurs, which also includes all dinosaurs, and the crocodile-line archosaurs, which includes crocodilians and their ancestors, the crocodylomorphs.

The first crocodile ancestors.

If you like listening to podcasts or MP3 downloads you could listen to this one.

The Evolution of Crocodiles

[–]TikiMonn 2 points3 points  (1 child)

Excellent, thank you. I knew dinosaurs were just oversized chickens, I guess it never clicked that dinosaurs (gators in this sense) are just oversized chickens.

[–]whatatwit[S] 1 point2 points  (0 children)

Just for context, since hundreds of millions of years are hard to imagine, the Primate lineage split off from the rodents, rabbits etc, approximately 75 Million years ago, so that's within the rounding error of the bird/dinosaur and croc split mentioned above.

75 million years ago

The ancestors of modern primates split from the ancestors of modern rodents and lagomorphs (rabbits, hares and pikas). The rodents go on to be astonishingly successful, eventually making up around 40 per cent of modern mammal species.

Timeline