Zoo Knoxville in Tennessee is investigating the sudden, mysterious death of 33 of their reptiles, calling it an unprecedented tragedy.
Workers found 30 snakes, a lizard, and two other creatures unresponsive Wednesday morning and immediately evacuated the building. The zoo’s vet team delivered oxygen to the reptiles and used ultrasound to detect heartbeats. Of the 52 animals living in the building, 19 survived, the zoo said on Facebook.
"We're at a loss at this point as to what happened," said Phil Colclough, a herpetologist with the zoo. "No other zoo has ever experienced something like this."
Three of the snakes — a Louisiana pine snake, Catalina Island rattlesnake, and Aruba Island rattlesnake — were critically endangered species. The pine snake is also one of the rarest vertebras in the United States, Colclough explained.
"There might be just a handful of these animals left in the world, so every one of them counts," he said.
Although still baffled by the loss, officials say preliminary lung examinations show the animals might have been exposed to an irritant, explaining that "something sudden and catastrophic occurred inside to alter the environment."
Tests for carbon monoxide, carbon dioxide, methane gas, and other harmful gasses all turned up negative.
The outdated building, constructed in 1974, could have also been a factor, Colclough added.
Reptile and amphibian specialists are also examining the animals’ bodies for clues. There's no indication that the animals suffered a virus or illness.
“These animals were important ambassadors who helped so many people understand the role snakes and lizards play in the balance of nature," Lisa New, president and CEO of the zoo, said in a statement. "We also lost breeding programs for several endangered and threatened species."