Re: It was only in recent years that I heard she was injured in that scene.

Here's what it says in her bio about that scene on Wikipedia:

Career
Backlinie's appearance in Jaws took three days to shoot, with Backlinie strapped into a harness while the crew struggled to get the desired effects. Contrary to rumor, Backlinie's startled reaction and screams of anguish were not due to her being injured by the harness that yanked her back and forth in the water. However, she was attached to a line that was anchored to the ocean floor beneath her, and she was intentionally not warned when she would be first pulled underwater; this helped provoke a more genuine expression of surprise from her initially – but the remainder of her performance was her own as an actress. When Jaws co-star Richard Dreyfuss saw a daily of her performance of being attacked by the shark, he told her it absolutely terrified him In the final edit of the film, Backlinie is the first victim of the monstrous shark.

Backlinie also appears in Spielberg's film 1941 parodying her role in Jaws: instead of being attacked by a shark during a midnight swim, she's "picked up" by the periscope of a Japanese submarine. The scene has been described as the best joke in what is otherwise widely considered one of Spielberg's least successful films.

Backlinie also appeared in the 1977 film Day of the Animals, regarded by some as a Jaws clone about nature gone bad.

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