Blue whale
There are less than 25,000 blue whales in the world. They are the largest mammals on the planet and in the only ocean they do not inhabit is in the Arctic.
It is believed that its population was reduced by 90% by whaling in the 20th century. This is the reason why commercial hunting of the species was finally banned in 1966.
Despite being so big, this giant of the ocean feeds on some of the smallest marine life, tiny shrimp like animals called krill. A single adult blue whale can consume 36,000 kg of krill a day.
Incredibly, Blue Whales are graceful swimmers cruise the ocean at over 8km/h, and can reach speeds of over 30km/h.
They mainly catch their food by diving, and descend to depths of approximately 500 m.
Blue whales have few predators (save the human of course) but are known to fall victim to attacks by sharks and killer whales, and many are injured or die each year from impacts with large ships.