How Baby Sea Turtles Find Their Way Home
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How Baby Sea Turtles Find Their Way Home


[OPENING MUSIC] Today’s episode is about something very
important: stratospheric carbon quantum resonan… just kidding! IT’S BABY TURTLES! [TURTLE MUSIC] OK, you’re about to see one of the cutest
things ever, but first I want you to ask yourself a question: Do you remember where you were
ten years ago, at this exact day and time? Not just the city, but the exact place. Could you find your way back there… without
a phone? Without a map? Probably not. But they can. Or at least they will. These are Kemp’s ridley sea turtles, Earth’s
smallest sea turtles, just a few days old, and instinct draws them toward the ocean. It’s dangerous out there, many won’t survive,
but ten or fifteen years from now, a few lucky females will perform one of nature’s greatest
feats of navigation… and find their way back here. Sea turtles are AWESOME. Some specis swim more than a thousand miles
to lay their eggs in the same sand where they were born. That’s like half an ocean, after being out
at sea for more than a decade. That’s crazy. To do this, sea turtles have some tricks up
their slee… um, under their shells. So do salmon…but they don’t have shells. Anyway, when it’s time to spawn, salmon leave the
ocean and swim upriver to the spot they were born. When they were babies, they saved a chemical
“snapshot” of how their home river “smells” Scientists think baby sea turtles do the same
thing, they *imprint* on the chemical cues around them: the sand, the ocean, whatever’s
near shore… all that says “this is home”… not bad for newborns. But when it’s time to come back, they can’t
smell their home beach from across an ocean. They have a different trick for navigating
long distances. One way humans know where we’re going is
to use a compass. That needle always points at Earth’s magnetic
north pole. But if we slide that compass along Earth’s
equator, the needle will move as it follows the pole. Now… imagine we rotate that compass straight
up in the air. At the magnetic north pole, Earth’s magnetic
field lines are perpendicular to the surface, so the compass points straight down. Near the equator, they’re parallel, so the
compass points sideways. You and I can’t feel this, but many animals
can sense these angles of inclination and declination. They can sense their x/y coordinates. We aren’t exactly sure *how* turtles sense
this. Some birds have iron crystals in their beaks
to navigate with magnetism, and so far scientists haven’t found anything like that in sea
turtles. But they’ve done experiments with captive
turtles, putting them inside magnetic fields, and we *know* they follow some sort of built-in
compass. Now… they don’t get it right *every* time. Sometimes turtles end up miles from where
they were born. But this might not be all their fault. Magnetic north moves, Earth’s magnetic
field shifts slightly year after year, so if a turtle’s at sea for 10, 15, 30 years…
their coordinates will point to a different place. This is why their first walk down the beach
is so important. They’re in geographic learning mode, sensing
the magnetic field, smelling chemical cues, feeling the ocean currents, storing them in
their brain until instinct brings them back, years later. Awwww look at how cute they are! But what if I told you these turtles almost
never existed. Because that’s true. Some history… In 1880, a guy in Key West found a weird
sea turtle locals called the “ridley”. He sent one up to Harvard, and they ended
up naming it after him. But the Kemp’s ridley was kindof… a riddle. People saw them at sea, but for almost 70
years, no one could figure out where they laid their eggs. In Mexico, Andrés Herrera heard a rumor that
thousands of turtles would sometimes crawl onto the beach on the same day, so he grabbed
a 16mm camera, hopped in his plane, and on June 18, 1947 he landed on the beach at Rancho
Nuevo to find this… The Kemp’s ridley nesting beach. An arribada, more than 40,000 females nesting
in a single day. This film literally sat in a closet until
1961, and when scientists finally went to see the nests for themselves, there was nothing
to see. People had harvested so many eggs, shrimp
boats had captured so many adults… the arribadas were no mas. We went from more than 120,000 nests in 1947
to fewer than a thousand in 1978. Kemp’s ridleys needed some TURTLE POWER
or they would go extinct. So scientists came up with an experiment no
one had ever done. It did NOT involve pepperoni pizza. TURTLE LEONARDO VO: I got a bad feeling about this. They moved eggs from Mexico to hatch in Texas…
hoping the baby turtles would imprint there and establish a new nesting site at Padre
Island. They tagged and released thousands of turtles,
and then waited. And waited. It took a while, but in 1996, a tagged, imprinted
turtle was seen nesting on Padre Island. It had been released in 1983. Dr. Donna Shaver leads Sea Turtle Science
and Recovery at Padre Island National Seashore. She’s been working with ridley’s for the
past 30 years. These days, her team collects eggs from Texas
beaches to hatch in captivity, and when they’re ready, the babies walk down the beach and
into the Gulf of Mexico. It’s worked pretty well so far. After a low of 702 nests worldwide in 1985,
there were more than 20,000 in 2009. And in addition to their home beach in Mexico,
turtles now nest in Texas every year. But ridleys are still the most endangered
sea turtle. After years of growth, the population has
been decreasing again since 2010, the same year the Deepwater Horizon oil spill happened
right the middle of one of their feeding grounds. Sea turtles – like Kemp’s ridleys – still
have a long journey in front of them, but they’re pretty good at finding their way… especially if they’ve got a little help. Stay curious.

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