Short answers, pulled from the story.
The blue whale is the largest known animal that has ever lived, reaching up to 29.9 metres in length and 190 tonnes in weight. It feeds almost exclusively on krill and has lungs that can hold about 5,000 litres of air.
Primitive cetaceans first entered the sea around 49 million years ago, descended from land-dwelling even-toed ungulates related to the Indohyus. Over millions of years, forelimbs became flippers, hind limbs disappeared, and nostrils migrated to the top of the skull to become blowholes. By 34 million years ago, the two modern groups, baleen whales and toothed whales, had diverged.
Baleen whales (Mysticeti) filter krill and plankton through keratin plates and have two blowholes. Toothed whales (Odontocetes) hunt fish and squid with conical teeth and have a single blowhole. Toothed whales also use a fat-filled organ called the melon to project echolocating clicks.
Whales rank among the most intelligent animals on Earth. Sperm whales have the largest brain mass of any animal, averaging 7.8 kg in mature males. Belugas and narwhals have a brain-to-body mass ratio second only to humans. Many whale species have spindle neurons linked to social conduct and emotional regulation, the same cells found in the human neocortex.
The whale pump, identified in a 2010 study, is the process by which whales carry nutrients from deep water back to the ocean surface through their liquid excrement. In the Gulf of Maine, whales contribute more than 23,000 metric tonnes of nitrogen per year, exceeding the combined input of all rivers flowing into that gulf, fuelling phytoplankton growth.
The American whaling industry reached its peak in 1853, earning US$11 million (equivalent to around US$348 million today). The International Whaling Commission placed a moratorium in 1946 setting catch limits per country, with aboriginal communities excluded until 2004. Current whaling nations despite IWC membership are Norway, Iceland, and Japan.