00:00Meet the manta ray.
00:09There are two distinct species, reef manta rays and giant oceanic manta rays.
00:21These big beasties are giant by name and giant by nature.
00:26The mature females can grow to a whopping 8 meters, which is roughly the width of a
00:31tennis court.
00:35But the really distinctive thing about mantas is their body shape.
00:41Their unique shape is highly streamlined, making them some of the most efficient swimmers
00:46in the ocean.
00:47Plus their skeleton is made entirely of cartilage, which is lighter and more flexible than bone.
00:56But they aren't putting on this underwater ballet just for me.
01:01In fact, manta rays have to keep swimming to stay alive.
01:06But why?
01:11The reason is all to do with oxygen.
01:14As the manta ray swims forwards, the horn-like fins on the front of its face help to funnel
01:20a current of water into its mouth.
01:23Inside the mouth are five rows of gills, each is packed full of blood vessels which absorb
01:29oxygen from the water into the ray's bloodstream.
01:34The water is then expelled through the slits on the underside of its body.
01:40So the only way the manta rays can stay alive is constantly swimming forwards, to push new,
01:47oxygen-rich water over their gills.
01:50If they stop moving, they die.
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