A new research by scientists has discussed that the blue whales turned into giants that they are right now because of their evolutionary past that involves the increase of ice sheets in the Northern Hemisphere. The blue whales could reach lengths for over 100 ft, the largest vertebrate animal that could ever live.
In the study published in Proceedings of the Royal Society B titled "Independent evolution of baleen whale gigantism linked to Plio-Pleistocene ocean dynamics," the study traced the evolution of whale size through more than 30 million years of history. The have found out that very large whales appeared along with several branches of the family tree for about two to three million years ago.
In addition, they have found out that the increasing ice sheets in the Northern Hemisphere in this period played a huge factor on the way whales' food was distributed in the large oceans and enhanced their body size.
Still, the main reason how and why whales got so big is still a mystery because of the challenges of interpreting some incomplete fossil record. "We haven't had the right data so how do you measure the total length of a whale that's represented by a chunk of fossil?" Nicholas Pyenson, a Smithsonian Museum curator of fossil marine animals and the lead author of this study, said.
Pyenson said that the width of a whale's skulls, however, is already a good indicator of its overall body size. With this advanced study, it is deemed by the researchers as the right time to address this question.
"We might imagine that whales just gradually got bigger over time, as if by chance, and perhaps that could explain how these whales became so massive," Graham Slater of the University of Chicago said. In an article published by Phys.org, he said that their analyses show that their idea does not hold up the only way that the whales' sizes could be fully explained.
Furthermore, Slater speculated that something has changed in the recent past of the whales that created an incentive in their size to be giant. He speculated that back then, it would be very disadvantageous for them to be small.
The study also said that the evolutionary shift of the whales took place at the beginning of the Ice Ages as a response to the climatic changes that would reshape whales' food supply in the world's oceans. When the glaciation began, the distribution of food sources run off from the new ice caps that would wash nutrients into coastal waters.
