Journalist and "Blackfish" producer Tim Zimmermann wrote Sunday about the possible stinging effects of chlorine in aquariums, describing how irritants can trigger a physical response in affected killer whales. Aquariums may turn to chlorine to keep their tanks looking crystalline, but misuse of the chemical cleaner poses a potential threat to both animals and trainers. It's not uncommon for trainers to get eye burns, Zimmmermann wrote, and trainers routinely spot mucus streaming from orcas' eyes.
Although SeaWorld contends that orca eyes normally produce mucus, killer whale experts such as Ingrid Visser say they've only witnessed wild orcas weep for extended periods when stranded, as a reaction against sand and other particles.
The Free Morgan Foundation, an organization that supports the release of a captive orca named Morgan, documents signs of irritation around her eyes in this series of photos.