The World Used To Be Full of Giant Tortoises

The world used to be full of giant tortoises, and the ones that live on the Seychelles and Galápagos islands are all we have left. But how did these big reptiles get to the islands in the first place? And why is turtle anatomy so weird?

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Host: Hank Green (he/him)
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Sources:
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Images:
Thumbnail photo: Dr. Dennis Hansen

[a.j.kimball]

You mentioned Komodo dragons being a case of insular gigantism, and while this is partially true, what's fascinating is that they are actually an example of insular dwarfism as well! Komodo dragons and their relatives were once widespread throughout South East Asia, and even into Australia. The ancestors of modern Komodo dragons likely reached their massive sizes on an island in SEA, but when they reached the tiny island of Komodo, they actually shrunk! So islands helped Komodo dragons reach their huge size, but they also shrunk em down a bit, and I find that to be fascinating.

[NewMessage]

When I was a kid, the teacher had us all stand up and tell the class what we wanted to be when we grew up, and after a litany of police, firemen, soldiers and sports stars, I stood up and proudly declared I wanted to be a tortoise.

Over 40 years later, I still stand by that declaration.

[PastelBat]

I am so happy you mentioned Jonathan!!! I have been fascinated by him for years and I even celebrated his birthday last year!

[theghosthero]

Something to note. This video says giant tortoise didn't exist in Australia. While it it true that giant tortoise didn't exist in Australia, this might be mostly due to the fact that niche was already occupied by stem tortoise, cousins of tortoise such as the giant meiolania, that existed there. They had horns and club like tails, pretty cool.

[meghanandrews]

This is exactly the turtle content I've been craving! Turtles and tortoises are the best! 🐢

[andrewstunich]

I was paddle boarding in Kauwaii several years ago when I observed a shadow in the water of to my right. I was initially scared it was a large shark but then as it swam underneath me I got a good look and it was a very latge turtle of some type. It was so big and beautiful that I was ecstatic to have had the opportunity to see it so closely in its natural environment unmolested.

[jansenart]

Make no mistake: most "herbivores" are only such because they have difficulty acquiring prey, and are actually opportunistic omnivores. You'll know what I mean if you've ever seen that horse with the chicks.

[dappertophat]

videos about animal/biology facts make me very happy. the existence of this channel makes me very happy.

[Kelly-ibhf]

Cannot express how much joy the Bizarre Beasts pin club brings to me. People ask me about the pins all the time and I get to geek out about how cool nature is. And I really enjoy defacing my (gifted) Kate Spade purse with nerdy pins.

[BattlingBeasts]

You guys forgot to mention the third giant tortoise- the sulcata tortoise of Central Africa which can grow up to two hundred pounds and is the only remaining mainland giant tortoise.

[TurtleNerite]

Technically, there was a giant tortoise in Australia, the Meiolania, though it is not closely related to the modern turtles. Instead its a stem-turtle whose group is a sister-taxon to the modern Chelonia.

[Balu_]

As a child of maybe 5 or 6 years, my family and I went to a zoo in Stuttgart. As a curious child, I went ahead of my parents in the reptile enclosure. When I see this huge tortoise my younger me just HAD to sit on that beautiful creature. The shell was super warm and felt extremely comftable. A minute or so later some adult person told me I should not do this, they can bite off fingers.
Big sad. I felt like I found a new buddy

[rammylive]

you should do an episode on the grasshopper nematode (Mermis nigrescens). with their unique method of locomotion when scanning for hosts and its atypical snake-like slithering otherwise, its thousands of eggs carried at a time, and its eye which only occurs in females and use of crystalline haemoglobin to help sense light (something not observed in any other organism), there is plenty to talk about. i reckon it could make a neat little pin, too.

[jamesjuggler]

I know this will sound crazy but I live in Minnesota and in 1998 or 1999 I was driving through the area around fort ripely near pillager mn. Suddenly I saw a van stopped ahead of me on the side of the road so I slowed down as I got closer I could see what looked like a bear laying in the middle of the road. When I got closer I could see it was shiny and not furry. It was a giant turtle and it was the height of the wheel well of the van and twice as long. It was huge. I didn’t have a cell phone back then but I took notice of how large it was based on how close to the van it was. They say this turtle does not exist but I saw it. It looked like a box turtle in its shape and I never saw its head as it was turned away. It was awesome.

[ManfredDudesonVonGuy]

1:20 killed me "I'm gonna get you!" *bird moves 3 inches* "DRAT! I'm still coming for you!" *repeat*

[Keenakeen]

"There used to be giant tortoises on every continent, except for Australia and Antarctica."

Meiolania, the Horned Tortoise: "Am I a joke to you?"

[ThatJaymsWisdom]

Still the greatest channel on YouTube. I'm having a terrible day (again) and this video really helped calm me down (again).

[Cowboy_Cowboy]

0:55 wait THATS how you pronounce Seychelles? I’ve only ever said it in my head and I’m so glad for that now

[ThatJaymsWisdom]

Thanks for putting the calendars on offer! I have now ordered one. When shipping to the UK was £11 on top of the £22 calendar price that seemed a bit much but now I can basically get it with free shipping (£22 all in) and that makes me very, very happy. Happy New year and much love <3

[IcyMidnight]

Foster's rule doesn't explain the giant tortoises, it simply describes it.