The toothy villain of “Jaws” terrified audiences in 1975. Offscreen, the hit film — which is celebrating its 50th anniversary — impacted sharks in unexpected ways.

After 450 million years of evolutionary history, shark populations are collapsing, and more than a third of shark species and their relatives face extinction. Now scientists are trying to use the lure of “Jaws” to advance shark conservation efforts.

Between the swingin' bed-hopping, its sweaty disco vibe, and the presence of a third-tier star in Priscilla Barnes (future Three's Company roommate Terri), this is a movie that seems tailor-made for a '70s drive-in double feature. By which I mean, it's a hoot. — C.N.