Alligators release heat through their wide open mouths, she said. Some visitors see the jaws as target practice.
"People will actually chuck coins right into their mouths," she said. "They don't have a spitting reflex like a mammal, so the next time they eat anything, they'll swallow them."
The alligator isn't the first animal to die because of foreign objects, D'Agostino said.
Brindle, a seal, died of metal poisoning in June 2007. When the seal was examined after death, 92 coins were discovered in her stomach. Her stomach acid triggered a reaction with the zinc in pennies. The toxic result was kidney failure.
Like the alligator exhibit, visitors sometimes throw money into the pool to make a wish. Coins that spin as they sink reflect sunlight, mimicking the appearance of a fish, D'Agostino said.
The effect is a lot like that of a fishing lure.
Keepers now X-ray the seals and sea lions twice a year. Any debris is removed.
But checking the alligators isn't so easy, D'Agostino said. Their stomachs can't be X-rayed. Each scale has a bone inside, so the armor prevents veterinarians from seeing beyond the scales.
An arthroscopic camera reveals the stomach contents, but anesthetizing, scoping and evaluating the alligators several times a year isn't ideal.
So zookeepers are working to educate the public about animal health and safety, she said.
They may modify the exhibits a bit to catch some of the falling debris.