Pelicans and whales are not especially close relatives. I’m about as closely related to Tyrannosaurus rex as they are to each other. The specialized, flying dinosaurs and the highly modified, aquatic artiodactyls (who long ago lost their hooves) last shared a common ancestor over 306 million years ago in the form of a visually unremarkable, lizard-like creature. But there is something that unites both pelicans and baleen whales together in an unnatural grouping of predators — a large expandable pouch suitable for scooping up writhing masses of little fish.

The way pelicans and many baleen whales feed is called “engulfment.” It’s exactly what it sounds like. These predators open their jaws wide to