I’m sure by now you’ve seen the viral images of a massive whale washed up on an Indonesian beach. The enormity of the then unfamiliar sea carcass got a lot of attention and got everyone asking, how did whales become so colossal? Scientists think they’ve got the answer.
Whales are the largest animals on the planet, but they haven’t always been giants according to Smithsonian paleobiologist, Nickolas Pyenson and vertebrate paleontologist Erich Fitzgerald.
The scope of their study focuses on the evolutionary land ancestry story of marine mammals somewhat 30 million years ago and how they’ve undergone this ecological change.
Whales, as it turns out, only became enormous in the past 3 million years or so and climate change probably triggered the transformation.
At the beginning of the ice ages, the oceanic ecosystem transformed on a grand scale. The ice sheets expanded and water circulation in the oceans changed dragging nutrients into the sea. Food sources began concentrating in certain places at certain times of the year, because water became deeper and moved closer to the equator. Later, the upwelling waters had patches rich in small fish and zooplankton like krill – the perfect meal for a whale.
This explosion of food in the ocean created a change in the environment which also meant that suddenly being bigger was better. The increased level of food led to a shift in body size distribution. Now more fat reserves meant whales could migrate for longer periods at a time.
These ecological factors transformed whales such as the krill-seeking blue whale from a few metres in size to the present giant size of up to 30 metres.
Understanding that climate change encouraged bigger giants in the ocean means that man-made climate change could possibly have the opposite effect. One thing is for sure, whales remain an intriguing anomaly.
Image credit: Thomas Kelley