Speaker 1: Welcome to brain Stuff, a production of iHeart Radio. Hey
Speaker 1: brain Stuff, Lauren Vogelbaum. Here, at some point, let's just
Speaker 1: say around two hundred and sixty million years ago, Earth
Speaker 1: got turtles. They look strange in these our modern mammalion times,
Speaker 1: when lots of things are squishy and unarmored, But during
Speaker 1: the Late Permian epoch, those early turtles were dressed in
Speaker 1: all the latest fashions, short sturdy legs, bony plates, and
Speaker 1: a stiff splayed crawling strut. Shortly after turtles made their
Speaker 1: evolutionary arrival, a fairly standard Earth thing happened a mass
Speaker 1: extinction event. Although mass extinctions have happened with some regularity
Speaker 1: on our planet, this one was a doozy, and it
Speaker 1: wiped out almost all of the life in the oceans
Speaker 1: and over two thirds of the vertebrates on land. The
Speaker 1: things that survived had to have been pretty good at survival,
Speaker 1: and it turns out turtles were. But we spoke about
Speaker 1: email with Laura Smith, a research scientists who specializes in
Speaker 1: herpetology at the Jones Center at ITUA, which is an
Speaker 1: organization in Newton, Georgia that promotes excellence and natural resource
Speaker 1: management and conservation. She said, turtles have a really successful
Speaker 1: body form that hasn't changed all that much over time.
Speaker 1: They've retained the primitive shell, which is a really protective,
Speaker 1: safe body design. Also, turtles live in a lot of
Speaker 1: different habitats. They're aquatic and also terrestrial, so living in
Speaker 1: a lot of different habitats has allowed them to persist.
Speaker 1: So well, what's the difference between tortoises and turtles. All
Speaker 1: of the animals alive today that protect themselves with a shell,
Speaker 1: which is basically just a modified rib cage, are in
Speaker 1: the order test studinies. Collectively, we call this group of
Speaker 1: animals turtles, but individually we might call them different things
Speaker 1: based on where they live and some morphological and physiological traits.
Speaker 1: Hortoises are a group that are generally always found on land.
Speaker 1: Smith said, they say that not all turtles are tortoises,
Speaker 1: but all tortoises are turtles. The turtles are organisms with
Speaker 1: a shell which might be in water or might be
Speaker 1: on land. A tortoise is a type of turtle. In general,
Speaker 1: both turtles and tortoises, as well as other reptiles, lay
Speaker 1: their eggs on land. It's what makes them different from amphibians,
Speaker 1: which need water for egg laying and at least part
Speaker 1: of their life cycle. Because tortoises are a type of turtle,
Speaker 1: it's difficult to lay down hard and fast rules about
Speaker 1: what makes something tortoises rather than turtle ish. But in general,
Speaker 1: tortoises are always found on land, whereas turtles can be
Speaker 1: found in aquatic or marine habitats as well as land.
Speaker 1: Smith said turtles and tortoises look different because of where
Speaker 1: they live. A sea turtle is only found in the ocean.
Speaker 1: The females are the only ones that come on land,
Speaker 1: and that's just to lay eggs. They have four legs,
Speaker 1: but the front legs are almost like wings or paddles.
Speaker 1: They're not great for moving around on land at all
Speaker 1: because they're adapted for swimming quickly. Their shells have a low,
Speaker 1: flat profile for cutting through the water. Compare that to
Speaker 1: a Galapa ghost tortoise, for example, whose body can weigh
Speaker 1: up to nine d and twenty pounds that's almost four
Speaker 1: d and twenty kilos. With stocky, elefantine legs, a high
Speaker 1: domed shell, and big scales on their exposed skin to
Speaker 1: protect them from predators, they wouldn't last long in the ocean,
Speaker 1: but luckily they don't have to. The Smith said, for
Speaker 1: the most part, there's not really one characteristic that tells
Speaker 1: you whether something is a tortoise or a turtle. But
Speaker 1: it's pretty clear. If you see a little turtle on
Speaker 1: the side of the road and it has a sort
Speaker 1: of flattened shell profile, webbed feet in the back, smooth skin,
Speaker 1: and some brighter colors, that's going to be a turtle.
Speaker 1: The tortoises have a heavier, more domed shell and subdued colors.
Speaker 1: As usual, the terminology can be confusing. Box turtles, for instance,
Speaker 1: which are widespread in the United States in Central America
Speaker 1: and don't really swim or spend much time in the water,
Speaker 1: but they're still considered turtles rather than tortoises. And then
Speaker 1: there are the terrapins, which is the name given to
Speaker 1: aquatic turtles in the United Kingdom. In the US, aquatic
Speaker 1: turtles are just called turtles, with the exception of the
Speaker 1: diamond back terrapin, which lives in brackish water in tidal
Speaker 1: marshes in the eastern United States. Both tortoises and turtles
Speaker 1: have made themselves at home on this planet. We find
Speaker 1: both on every continent other than Antarctica. With one exception,
Speaker 1: there are no tortoise species native to Australia. Smith said
Speaker 1: the greatest diversity of aquatic turtles are in Southeast Asia
Speaker 1: and in the southeastern United States. The greatest tortoise bio
Speaker 1: diversity is in South Africa. And there used to be
Speaker 1: more giant tortoises across the world, but now there are
Speaker 1: just remnants on the Galapagos and Aldebra places like that.
Speaker 1: Giant tortoises do occasionally disperse, or more likely drift across oceans,
Speaker 1: basically by surviving for weeks or months bobbing around. In
Speaker 1: recent years, an aldebrand tortoise with barnacles on its shell
Speaker 1: washed up in East Africa, and that's not bad for
Speaker 1: something that started its life in the Indian Ocean. Today's
Speaker 1: episode was written by Jesceline Shields and produced by Tyler Clang.
Speaker 1: For more on this and lots of other curious topics,
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