MELBOURNE - Last month, at the Sea World amusement park in Florida, a whale grabbed a trainer, Dawn Brancheau, pulled her underwater, and thrashed about with her. By the time rescuers arrived, Brancheau was dead. The death of the trainer is a tragedy, and one can only have sympathy for her family. But the incident raises broader questions: was the attack deliberate? Did the whale, an orca named Tilikum and nicknamed Tilly, act out of stress at being held captive in a sterile concrete tank? Was he tired of being forced to perform to amuse the crowds? Is it right to keep such large animals in close confinement?