Phoebe Beltran was in the home stretch of her 1,000-yard swim when she suddenly felt an intense pain as the sea lion bit her right arm.

A common neurotoxin produced by algae blooms is making California sea lions more aggressive. Here’s why it has the power to change behavior—and the danger it poses.

15-year-old Phoebe Beltran has several cuts on her right arm and was hospitalized following the confrontation with the animal on Sunday. Although she has since been released from the hospital and was well enough to return to school, she said the attack has left her shaken up.