Balaenopteridae

About the rorquals

The family name comes through Latin from the Norwegian røyrkval, "furrow whale", for the ventral pleats that run from chin to navel. In a lunge those pleats unfold, the lower jaw drops to nearly ninety degrees, and the whale takes in a mass of prey-laden water that can exceed its own body mass; the throat then contracts and drives the water out through the baleen. A sensory organ at the tip of the chin, unique to rorquals and only described in 2012, appears to coordinate the whole manoeuvre.

Everything else about the body follows from that: a long, streamlined shape built for the acceleration a lunge needs, a small falcate dorsal fin set far back, and comparatively short baleen. The humpback, placed in its own genus, diverges most — enormously long flippers, a stockier build, cooperative bubble-net feeding and song.

Rorquals were largely out of reach of open-boat whaling: too fast to chase under sail, and dense enough to sink when killed. The steam catcher, the explosive harpoon and the factory ship removed all three protections within a few decades, and the twentieth-century industry worked through the family from largest to smallest. The consequences are still legible in the conservation status of the individual species.