Most carnivorous plants are full-time predators—the Venus fly trap, for example, lies in wait year-round to snag flies with its jawlike leaves.

Yonggang Hu, a developmental biologist at Indiana University in Bloomington, suspected a link between beetle horns and wings after discovering last year that gin traps—defensive jawlike organs on beetles’ abdomens—rely on wing genes to grow.

Pelican spiders, so-called because of a long neck and long jawlike appendages, make a living by hunting and killing other spiders.

Venus flytraps get their nutrients from the insects they lure with nectar and trap with a pair of jawlike leaves.

Fifty feet above the deck, crane trolleys flew through the air, their jawlike spreaders plucking boxes from the giant vessel’s hold.