Blue whales do still exist and there are 5 recognized subspecies of blue whales.
Today the number of blue whales is only a small fraction of what it was before modern commercial whaling reduced the number of whales significantly during the early 1900s.
However populations of blue whales are increasing globally still.
Before whaling began, there may have been as many as 250,000 blue whales, but today, the blue whale is one of the world's rarest species of whales, with a population of just 10,000-25,000.
The blue whales face a multitude of threats from human interference.
Blue whales are a marine mammal and a baleen whale.
Blue whales reach a maximum confirmed length of 29.9 meters and weigh up to 199 tonnes, and they are the largest animal known ever to have existed.
A blue whale's long and slender body can be of various shades of greyish-blue dorsally and somewhat lighter underneath.
The blue whale is the largest known animal to have ever lived.
An adult blue whale can grow to a massive 30m long and weigh more than 180,000kg which is about the same as 40 elephants, 30 Tyrannosaurus Rex or 2,670 average-sized men.
Primary threats blue whales face include commercial whaling, noise pollution, ship strikes, and climate change, which affects their food sources and habitats.
The blue whale has a dive time that varies from around 10 to 30 minutes, which is not enough to earn the species the record for the longest dive.
Blue whales were targeted for the rich rewards their huge bodies held.
The whaling ships used in the twentieth century were fast enough to catch even the quickest whales, and had mechanical weapons on board - including exploding harpoons.