Baleen whales grow large
Stronger upwelling produces dense patches of prey, and filter feeders scale up to exploit them.
- When
- —
- Duration
- 8.7 million years
- Known to
- ± 2 million years
- Era
- Miocene, Cenozoic
As ocean circulation strengthens and upwelling intensifies through the Miocene, krill and small fish concentrate into denser, patchier swarms. Large body size becomes advantageous for a filter feeder: it allows longer fasting between patches, cheaper long-distance travel, and gulps that scale faster than body mass. Mysticete size increases through the epoch, though the true giants — blue and fin whales — only appear later, when Pleistocene glacial upwelling makes prey patches denser still.