What would you do if you were face-to-face with a predator? If you were a hagfish, you’d drown your opposition in slime. If you were a fulmar chick, you’d project a foul vomit, so powerful it destroys the feather waterproofing of your nemesis.

John Downer’s “Weird Nature – Devious Defenses” highlights the unusual natural defenses many animals possess, from camouflage and armor to toxic sprays.

Merrielle Spain of Caltech’s Computation and Neural Systems Department will introduce the high-definition film, which was produced for BBC and Discovery Channel, and lead a post-screening discussion. The event is part of Caltech’s Science Saturdays family series.

— Tracy Spicer