Coming up next on Jonathan Bird's Blue World,
Jonathan investigates the world's largest rays!
I've come to Yap, Micronesia, famous for its huge stone money...
and its giant manta rays.
Hi, I'm Jonathan Bird and welcome to my world!
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Yap is a remote island in the Pacific—about halfway between Japan and Australia.
Divers travel here from all over the world to see an amazing and huge animal.
I'm talking about manta rays, the largest rays in the world, and they should be right
under the boat! Let's go take a look!
As I drop into the water, I notice that it's pretty murky.
I'm diving in a channel through the fringing reef, between the open ocean and the land.
As the tide changes, water flows in and out of this channel.
When it flows out, it takes nutrients from the mangroves with it, and the water becomes
The current is moving me along rapidly, and I ride it like a river, following my guide
John to a section of reef where we hope to find mantas.
I tuck into a position at the base of a coral head, out of the current, and wait. The swift
current blows the coral polyps like wind, and sweeps along pieces of eelgrass and mangrove
leaves from the lagoon.
I wait a long time. It takes nearly an hour, but finally a shape emerges from the murky
distance.
I would recognize that shape anywhere—the beautiful and graceful motion of a manta ray,
soaring like a huge bird through the water. It stops over the coral.
A dozen or so tiny fish converge on the ray while it hovers, just over their home. The
fish are cleaner wrasses. They pluck parasites from the rays, and this coral head is known
as a cleaning station.
It's a great symbiotic relationship because both the fish and the rays benefit from it.
The fish get a meal of tasty parasites likes copepods and scraps of dead skin, while the
manta gets rid of parasitic annoyances that can cause infection.
Cleaning is not always a pleasant experience though. Sometimes one of the cleaner fish
nibbles a little too hard and the manta jumps away.
At the end of my dive, I do a short decompression stop for safety, then head up.
That was incredible! The current was really strong and it was blowing me back and I could
barely hold on, but the manta ray was just flying gently into the current, holding its
position over the cleaning station. It's really incredible to see.
It's no coincidence that the mantas like a little bit of current while they are being
cleaned.
Mantas, like all rays and sharks, have no swim bladder. A bony fish can hover in mid-water,
perfectly still, because it has a swim bladder to control its buoyancy. Sharks and rays sink
if they stop swimming.
The enormous wings of the manta, reaching 25 feet across, allow them to fly though the
water like a bird. And like a bird, if they stop flapping, they will begin to glide towards
the bottom.
The mantas come to the cleaning station at a particular time, but it has nothing to do
with the time of day. Like a runner on a treadmill, the mantas require just the right amount of
water movement so they can swim in place to be cleaned by the fish. They follow the timing
of the tides, preferring to be cleaned just before or after slack tide, when the water
is moving, but not too fast.
This manta is holding its mouth wide open so the cleaners can go inside.
As long as we don't get too close, the mantas are not bothered by our cameras and bubbles
at all.
There are only a few prime cleaning stations, and they have become social stops as much
as hygienic visits. Often there are a dozen or more manta rays at the cleaning station,
all taking turns being cleaned, and interacting with each other while waiting.
Each manta ray has a unique pattern of spots on its belly, which can be used like a fingerprint
to identify it individual animals Here at Yap Divers, they have been documenting and
photographing these spot pattern for many years, and they have identified more than
60 individual manta rays and giving them nicknames. This morning I got to meet Zorro.
Zorro has three little spots and a pair of stripes between her gills.
Underwater, she was easy to identify: the three spots, and the stripes.
Being able to identify individuals has proved that the mantas around Yap stay here for long
periods of time. They're not just passing through—they live here, and the divers see
the same ones over and over and over.
Yap has more to see than just mantas though. I cruise over to the other side of the island
to explore the outer reefs.
There I see magnificent coral and crystal clear water, far away from the murky water
in the channel.
I swim with a big school of barracudas. When I get too close, I spook them.
I watch a sea turtle munching on a sponge.
And I swim in magnificent coral caverns—tunnels that snake between the coral heads and make
me feel like I'm exploring another planet.
Yet, at the end of my dive, as I emerge from the cavern, I see another manta ray flying
over, far from the cleaning station. It's almost as if this single manta has come to
bid me farewell. It's a magical and fitting end to an astonishing journey.
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