When thinking of a whale, one immediately associates the mammal with a massive size. However, a new study suggests that whales may not have been as big as they are presently.
Researchers from the Smithsonian’s National Museum of Natural History determined that prehistoric whales were relatively smaller than their present-day counterparts.
The study revealed that giant whales first started appearing in the oceans around 2 million to 3 million years ago.
Why Did The Whales’ Size Increase?
Researchers studied 30 million years of the whales’ evolution. They found that very large creatures of the species showed up along different family branches roughly 3 million years ago, which scientists say is relatively recent.
To ascertain what could have led to the whales’ size increase, researchers focused on the creatures eating habits. Most very large whales use baleens to hunt for their food. Baleens are essentially filters that ensure whales only ingest food such as krill and smaller fishes when they gulp the ocean water. While the whale spits out the excess water, the fish and krill are ingested.
Scientists wondered if the baleen’s evolution over the years had was linked to the size increase among the whales.
“Baleen evolved about 20 million years ago, and we didn’t see the evolution of gigantism until about very recently, about 3 million to 5 million years ago,” the study’s researcher Jeremy Goldbogen explained.
Goldbogen and his associates believe that as the baleens started growing bigger, the ice age started. This resulted in not only increased runoff, but also greater ocean nutrients. Researchers also believe that the greater ocean upwelling impacted the change in whales’ size.
For the unfamiliar, upwelling is the process where high intensity winds may erode the surface water, which results in deeper waters replacing the former. These deep waters are rich in nutrients and provide ample food for the whales.
Scientists surmised that ice age, coupled with the increased upwelling, eventually led the whales to become bigger.
Science Behind The Whales’ Evolution
Bigger whales use a lot of energy to open their mouths to gulp water and feed themselves. However, a single gulp of nutrient-rich water that existed 3 million years ago provided ample food for the bigger whales.
“As animals are getting bigger, they’re getting much more efficient. So for every gulp, they’re getting tremendous amounts of energy” Goldbogen added.
This increased food availability without having to constantly move around in the ocean, is what scientists believe caused the whales to evolve from having a body mass of 10 tons to 100 tons in a matter of just 3 million years.
The study’s results were published in the journal Royal Society B on Tuesday, May 23.