Humpback whales being tagged by the research team off the coast of Antarctica in 2018. The team's findings, reported online Dec. 12 in the journal Science, reveal that body size in all whales is limited by the availability of their prey, but only filter-feeding whales have evolved a feeding strategy that rewards and drives them to achieve the largest body sizes to have ever evolved on Earth.
The new study underscores the precarious position that all whales hold within their ecosystems. "You have to wonder just how perilous it is for whales living on an energetic knife's edge," Pyenson said--particularly in the face of climate change, overfishing and other threats to the oceans.
"If you're a blue whale and your only prey item is krill, and something causes krill populations to go into decline, then you are at an evolutionary dead end because you would not be able to eat enough to sustain yourself," he said. "It's a good reason for us to try to better understand these predator-prey relationships."