"Next, Slater and his colleagues checked to see what was happening in the world at the time to cause the change. They found that the baleen whales' growth spurt coincided with the beginning of the first ice ages. As glaciers expanded, spring and summer runoff poured nutrients into the coastal ocean, fueling explosive growth in krill and small animals the whales consumed, they speculate. Until that time, prey had been uniformly distributed and plentiful, but the climate change caused many fish and big sea animals to disappear, and productivity plummeted. That seasonal runoff created a new pattern of food availability: seasonal patches of very abundant food spaced far apart over the course of the year.
Goldbogen helped Slater and Pyenson understand how that change was important. He studies whale eating and diving, and his work indicates that the more concentrated the food, the more efficient the feeding, especially in whales with really, really big mouths. Furthermore, larger whales can travel faster between patches of prey. So baleen whales that got bigger, faster, thrived, whereas smaller species went extinct. And their giant size may have even promoted greater productivity, “by bringing up nutrients from deep waters as they dive and resurface,” suggests Geerat Vermeij, a paleobiologist at the University of California, Davis, who was not involved in the work."
To be honest, never thought about this question before opening this article, and I probably won't think about it again, but I'm enjoying this moment of curiosity and satisfaction.
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