Scan, stun, eat
The green sawfish’s rostrum is studded with more than 40 dagger-sharp toothlike scales. It’s also lined with thousands of electroreceptors for scanning the water and ocean floor for prey. The sawfish whips its saw into a school of small fishes, then circles back to pick up stunned and injured prey, along with bottom-dwelling invertebrates, eating them whole with its small mouth. Ginsu, however, has been trained to take her carefully measured diet of mullet, herring and mackerel from extra-long tongs.
Only the biggest, boldest predators, like bull and tiger sharks, dare to tangle with adult green sawfish. But commercial fishing nets are an ever-present danger. The same Indo-Pacific coastal waters that green sawfish favor are prime commercial fishing grounds. Sawfishes drown when their rostrums get tangled in long trawl lines and gillnets. All sawfish species are either endangered or, like the green sawfish, critically endangered—warnings that they face a high risk of becoming extinct in the wild.
Surgery for a sawfish
For the well-being of Shedd's largest fish and the team that cares for her, keeping a safe distance is the best policy unless Ginsu absolutely requires hands-on attention. In mid-summer 2015, she did. An aquarist noticed a mass on the underside of a fin. Shedd's veterinary team agreed that the growth had to be removed. The carefully planned surgery was an interdepartmental effort.