Far bigger than any dinosaur, 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 – that’s about the same as 40 elephants, 30 Tyrannosaurus Rex or 2,670 average-sized men. But this giant among giants started as something far smaller.
Like all whales, the blue whale (Balaenoptera musculus) evolved from a four-legged mammal that lived on land some 48 million years ago. This ancient ancestor, Pakicetus, was only 1.8m long. It foraged in streams and some of its descendants became adapted to living in water. This eventually led to a completely aquatic creature called Dorudon (“Spear-Tooth”), which lived 37 million years ago and grew 4.5m long.
Blue whales can dive for up to an hour at a time, going to a depth of 100m, so they need highly efficient lungs to survive. Two enormous blowholes, big enough for a small child to crawl into, allow the fast and efficient exchange of oxygen. Blue whales exchange between 80 and 90 per cent of oxygen in their lungs each time they breathe, compared to just 10 or 15 per cent in humans.
Credit : BBC Earth
Picture Credit : Google
