Good morning, John!
Welcome back to Bizarre Beasts: Season Zero.
Hank and I are trading off hosting duties on our year-long journey to remaster the original
Bizarre Beasts episodes from vlogbrothers with corrections, updates, and new facts.
Around a hundred million years ago,
the continent that is currently North America was two or three large islands.
And slicing through the space between these islands was a massive,
shallow ocean called the Western Interior Seaway.
It stretched all the way from the Gulf of Mexico to the Arctic Ocean.
And at its deepest, this giant sea was just 900 meters deep.
For comparison, the deepest point in the Mediterranean Sea
is 5,000 meters deep.
It was warm, it was shallow, there were rivers from all
over the place dumping nutrients into this thing.
And today, all over the interior of America, you can still see the remnants of that time.
There are these little cylinders, they look like maybe crystals or
fossilized plant parts.
But, really, they are the remains of crinoids.
These tree-like filter feeders blanketed that sea.
But they were not plants.
They were animals.
Beautiful animals.
And if you've ever wanted to see a fossil come to life, I've got good news for you.
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One, crinoids are still common on Earth, as they have been for nearly half a billion years.
And, two, they do not disappoint in their beauty and oddity.
Crinoids come in two main flavors today: the stalked kind, which we
call sea lilies, and the un-stalked kinds, which we call feather stars.
And I wanted to pause here just to give you a little more background info on these guys.
There are more than 660 species of crinoids alive today, only about 80 of which are sea lilies.
Most of the sea lilies live in water that’s deeper than 200 meters, so, relatively deep.
The feather stars, on the other hand,
tend to live in reef ecosystems, which are found in water shallower than that.
And sea lilies used to be much more common, but they nearly got wiped out during the mass
extinction at the end of the Permian Period, around 252 million years ago.
After that, feather stars evolved and took over shallow water habitats.
Now, they look more like a kind of coral than anything else.
Like, that they would just sit, anchored to one spot in the ocean,
filtering plankton out of the water and chillin' out.
But corals are collections of tiny organisms, and corals are very much stuck to one place.
Crinoids are animals.
They are macro organisms like us and they can, though they don't often, move.
Oh, yeah.
I mean, I maybe forgot to mention the main thing about feather stars, which is this.
Like, you've probably seen viral videos of this movement,
but it isn't the kind of thing that, like, it hurts to watch again.
Crinoids spend almost all of their time sitting in one spot,
but they spend almost all of their viral video time engaging in this
amazing, mesmerizing locomotion.
Like other echinoderms, like starfish, sea urchins, sea cucumbers, etc.,
feather stars are pentaradially symmetrical.
They have five-sided symmetry.
This is harder to see in crinoids, but it is a thing.
They might have any number of legs, but that number should be divisible by five,
except that they often get their legs chewed off or knocked off.
They are pretty delicate but they could just grow them back.
And while feather stars move around looking like the most unearthly gorgeous thing that has yet
happened, sea lilies, which are essentially the same thing--like, they're different species,
but very similar--when they move around... yeah, they just drag their stalk behind them.
Just trudging across the ocean floor!
And I actually just learned this bonus fact that might explain why
otherwise sedentary sea lilies sometimes do this!
In a study from 2010, researchers put crinoids and pencil urchins
together in a tank to see if the urchins would eat the crinoids.
And...yeah, they did.
Which is maybe a little weird, because there’s not much on a crinoid that looks edible to me,
but an urchin’s gotta do what an urchin’s gotta do.
The researchers then studied the marks left behind on the crinoid parts by the
urchin’s beak-like mouth and went looking for those same marks on crinoid fossils
from around 230 million years ago, in the middle of the Triassic Period.
And they found them!
So, based on this and on when crinoids that can swim and drag themselves around originated,
the researchers think that predation by ancient urchins might’ve been one of the
evolutionary pressures driving crinoids to need to get away.
Check this out: Their blood--they have a vascular system--their blood is just water.
It transports oxygen and nutrients and waste.
It does the whole vascular system thing, but it's just seawater.
We're talking about an organism that figured out
how to do its thing before blood existed and is still doing that.
But crinoids have continued to adapt.
Like their locomotion--that wasn't happening 500 million years ago.
That's relatively recent.
I mean like 200 million years ago, but still.
Crinoids, y'all did it.
Good work.
Just keep swimming, I guess, is what this is.
If you missed this critter the first time around, our Season Zero pin sets are now available!
This set includes all 12 of the animals we began this Bizarre Beasts journey
with on Vlogbrothers, including the Feather Star!
And this one really glows in the dark!
To get the Season Zero Pin set, visit bizarrebeastsshow.com!
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