Deep ocean creatures II/II

From BBC Blue Planet

This is the most unexplored area of the planet: the deep ocean.

It begins with a whale shark used as a shield by a shoal of bait fish to protect themselves from yellowfin tuna.
Also shown is an oceanic whitetip shark trailing rainbow runners.

Down in the ocean's furthest reaches, some creatures defy the classification.
On the sea floor, scavengers such as the spider crab bide their time, awaiting carrion from above.

The volcanic mountain chain at the bottom of the Atlantic Ocean also sustains life through the bacteria that surround its sulphide vents.
There are thought to be around 30.000 undersea volcanoes, some of them taller than mount Everest.
Their sheer cliffs provide anchorage for several corals and sponges. never the surface, the currents that surround these seamounts force nutrients up from below and thus marine life around them is abundant.

Ascension Island is a nesting ground for fritebirds and green turtles.
Off the mexican coast, a large group of sailfish feed on another shoal of bait fish, changing colour to signal their intentions to each other, allowing them to coordinate their attack.

The last sequence depicts the largest animal on Earth: the blue whale, of which 300 000 once roamed the world's oceans.

Now fewer than 3% remain.....