Blue whale size mystery solved

Growing up to 30 metres long and weighing a whopping 200 tonnes, blue whales are the largest creatures on the planet. However, fossil records suggest that baleens (the species of whale to which blue whales belong) were originally no more than about 10 metres long. So how did they end up becoming the colossal creatures that exist today? The results of a recent scientific study could hold the answer.

Millions of years ago, baleen whales roamed the seas, eating small marine life such as plankton and krill. Their favoured foods were plentiful and they didn’t have to travel far to find them. Then, around 4.5 million years ago, climate change caused the oceans to get cooler. One result of this was that krill populations massively increased in certain areas of the ocean but disappeared in others. The whales feasted on their favourite foods, but often had to travel long distances between meals.

Large whales were better suited to travel than their smaller relatives. They could reach feeding zones more easily, and their big mouths meant that they could quickly gulp down huge amounts. This meant that bigger whales were able to reach the krill before the smaller whales, and they could eat it faster, too. Size was clearly an advantage and – according to the study – it was this, combined with their excellent diet, that led to big whales getting bigger and the smaller whales dying out.