APPLE VALLEY — A necropsy will be done Tuesday to determine what caused the death of a dolphin calf at the Minnesota Zoo.

The zoo’s marine mammal staff and veterinarians had been working around the clock to monitor and treat Taijah since she became severely ill early Monday. An ultrasound showed fluid in her stomach. Zoo officials say the young dolphin was put on medication and seemed stable until late Monday when she died.

The zoo’s director of biological programs, Kevin Willis, says Taijah was a favorite among staff because of her spunky personality and playfulness. The dolphin was born in 2010 to a 24-year-old bottlenose dolphin named Allie and 48-year-old Semo, which the zoo says is the oldest dolphin in human care.