(Airs Sunday, June 28) Underwater cameraman Bob Cranston explores the remarkable world of marine creatures called cephalopods -- squids, cuttlefish, octopi, and nautili.

Cuttlefish, along with octopuses and squid, are cephalopods — animals from an ancient branch of the tree of life that have been trolling the oceans for more than 500 million years.

NATURE takes you into the depths of the ocean to discover the most remarkable life still undiscovered on our planet that will certainly be found in the sea.

NATURE takes you into the depths of the ocean to discover the most remarkable life still undiscovered on our planet that will certainly be found in the sea.

NATURE takes you into the depths of the ocean to discover the most remarkable life still undiscovered on our planet that will certainly be found in the sea.

NATURE takes you into the depths of the ocean to discover the most remarkable life still undiscovered on our planet that will certainly be found in the sea.

NATURE takes you into the depths of the ocean to discover the most remarkable life still undiscovered on our planet that will certainly be found in the sea.

NATURE takes you into the depths of the ocean to discover the most remarkable life still undiscovered on our planet that will certainly be found in the sea.