The largest of August Krogh animals: Physiology and biomechanics of the blue whale revisited.

The blue whale is the largest animal ever. This gigantism probably evolved to exploit seasonal krill blooms, where massive feasts allow for accumulation of large blubber reserves that can fuel their low mass specific metabolism during prolonged periods of fasting. Until recently, the physiology and biomechanics of blue whales could only be inferred from anatomical inspections, but the recent development of biologging tags now provide unique insights into how these ocean giants function and interact with their environment. Their mandibles, the largest bones ever to evolve, along with a highly expandable buccal cavity, enable an extreme and dynamic bulk feeding behavior. During a lunge feeding event, blue whales accelerate up to 5 m/s to engulf a volume prey laden water that is commensurate with the whale's gigantic body size. Perhaps due to the costs of such extreme foraging, their dive times of 10-15 min are much shorter than scaling would predict for their size. Like other diving animals, blue whales display a dive response with heart rates down to 4 BPM to prolong dive times and perhaps mitigate decompression sickness. Blue whales make the lowest and most energetic calls of any mammal with ocean traversing potential under natural ambient noise conditions. However, communication space may be severely reduced due to pervasive shipping noise. We hope that an increasing ability to study the physiology and behavior of blue whales and other marine megafauna will enable informed decisions and ensure our permanent co-existence in the face of increasing human encroachment into marine habitats.