the coast of Florida.

And with them come grey mullet,

on their migration to their spawning grounds in the south.

Millions of them,

and packed so tightly,

they stay in the water

like an oil slick.

Few people on the beach

are even aware of them.

The mullet keep as close

to the shore as possible.

For in deeper water,

there are predators.

Close to the beach,

they have to keep clear

of human swimmers.

But now, hunters from the open ocean

have detected them.

Tarpon, over two metres long

and weighing over 100kg.

To get close to the mullet in the shallows,

the tarpon turn on their sides.

Now the mullet can't see

their shining, silver flanks

until it's too late.

And feasting begins.

Blacktip shark arrive.

Pelicans join in.

But these attacks have little effect

on the immense shoals.

The mullet outnumber their enemies

by 10,000 to one.

So the great procession travels on

into the northern Atlantic Ocean,

where, at last, they will be able

to spawn in safety.