英语听力：自然百科 海洋天堂大堡礁:堡礁内外—14（在线收听）

 And extremely cold, at 4 degrees, it's the same temperature as the sea in the Antarctic, the ROV reaches a depth of 800 meters, not quite at the bottom, but not far off, a pilot of coral sand at the base of the reef wall slopes gently into the abyss, and here we find signs of real deep sea creatures, some like the sea anemone are familiar, others are less well known, like this chamber nautilus, it's an ancient relative of octopus and squid, a living fossil, a last survivor of a group of animals that dominated the world's oceans 500 million years ago, it moves around by jet propulsion, squirting water backwards in order to go forwards. At night it's the nautilus' turn to migrate, it swims up towards the surface to feed on shrimps beside the reef wall, returning back down during the day. This is a baby nautilus, the first time one has been filmed in the wild, it's no bigger than a two pound coin, yet it makes the same daily up and down journey as its plate sized parents.