December 1, 2022

North America’s Rarest Snake Found Dead

Rim Crowned Snake LeafRim Crowned Snake Leaf

The rim rock crowned snake was found dead in the Florida Keys, locked in lifeless combat with a giant centipede it had managed to swallow halfway. Credit: Drew Martin

The snake was recently spotted for the first time in four years.

After a four-year absence, the rarest snake in North America, the Tantilla oolitica (rim rock crowned snake), was recently discovered at a park in the Florida Keys. The snake encounter was more of a source of astonishing awe than anything else, despite the fact that this would typically be a reason for joy among conservationists. The snake was discovered dead, engaged in a lifeless struggle with a massive centipede that it had partially swallowed.

The deadly confrontation is the first time the snake’s feeding habits have been observed by experts. Although it is known that closely similar species love centipedes, T. oolitica is so rare that no one was sure what it consumed until now. The interlocked pair was CT scanned by Florida Museum of Natural History researchers, who recently reported their findings in the journal Ecology.

“I was amazed when I first saw the photos,” said co-author Coleman Sheehy, the Florida Museum’s herpetology collection manager. “It’s extremely rare to find specimens that died while eating prey, and given how rare this species is, I would never have predicted finding something like this. We were all totally flabbergasted.”

Rim Crowned SnakeRim Crowned Snake

The fatal duel marks the first time that scientists have observed the snake’s eating habits. Credit: Florida Museum photo by Jerald Pinson

The snake was first spotted by a hiker in Key Largo’s John Pennekamp Coral Reef State Park, who then informed park personnel. In order to determine the precise cause of death, the specimen was swiftly sent to experts at the Florida Museum of Natural History.

Given that the centipede was only one-third the size of the snake, asphyxiation would be the most obvious theory. But snakes have a reputation for devouring prey that is far bigger than they are. Snake jaws are kept in place by flexible ligaments and muscles that enable them to wrap their heads around their prey, in contrast to humans and the majority of other vertebrate jaws that are directly attached to the skull.

Researchers would need to look inside in order to be certain. This used to need a dissection, which causes irreparable harm and might impede future research. However, more recently, researchers have turned to CT-scanning technology, which offers an unparalleled view of an organism’s anatomy without harming the specimen.

Jaimi Gray, a postdoctoral associate at the museum, stained the snake with an iodine solution to enhance the contrast of its internal tissues and constructed a fine-scaled 3D model from CT scans.

“We were able to perform a digital autopsy, which allowed us to examine the centipede and snake, including its injuries and gut contents, without ever picking up a scalpel,” she said. After scanning, the specimen was de-stained and now remains intact on collection shelves at the Florida Museum for future researchers to study.

The model revealed a small wound on the snake’s side, likely imparted by the centipede’s powerful venomous pinchers. Snakes that commonly dine on centipedes are thought to have some measure of resistance to their mélange of caustic venom, but that assumption has yet to be definitively demonstrated, Sheehy said. The bite seemed to cause some internal bleeding, but neither that nor the toxin was enough to deter the snake from killing and partially swallowing its prey.

Instead, the final blow seems to have been dealt by the centipede’s size. Close inspection of the CT scans shows the snake’s trachea was pinched at the approximate location where the centipede’s circumference was the largest, cutting off its air supply.

The results offer an intimate glimpse of a species many fear is on the verge of extinction. Tantilla oolitica once thrived in pine rocklands that spread from Central Florida south to the Keys but has since undergone a severe reduction in population size. The species has been listed as threatened in Florida since 1975, and efforts are underway by the U.S. Fish and Wildlife Service to have the species federally listed.

Pine rockland ecosystems evolved for millions of years along the spine of an ancient coral reef, harboring a long list of rare plants and animals found nowhere else on Earth. But the same attributes that fostered the growth of hyperdiverse forests also made this part of Florida an ideal place to build towns and cities. Today, an uninterrupted sprawl of development, from Miami to West Palm Beach, has almost entirely replaced the native ecosystems. Outside of the Everglades, only 2% of the original pine rocklands remain. For animals endemic to pine rocklands, like T. oolitica, the new cityscapes have meant near annihilation.

“We can’t say for sure whether or not they’re still present in peninsular Florida. Absence of evidence is not evidence of absence, but their habitat has basically been destroyed,” Sheehy said.

For now, researchers are encouraged by what seems to be a somewhat stable population of T. oolitica in Key Largo and plan to make as much use of the new specimen as possible. The CT scans are available online or free, and there’s no shortage of new information that can be gleaned from them.

According to Shefehy, anyone interested in this specimen can access the CT-scan data to look at other aspects of the snake’s anatomy, and because this is the first CT scan for the species, they’ll be the first people to make those discoveries. “This study is just the beginning of what will be learned about this enigmatic species from the CT-scan data,” he said.

Reference: “What killed the rarest snake in North America?” by Kevin M. Enge, Jaimi A. Gray, Coleman M. Sheehy III, Trudy Ferraro, Drew M. Martin and Jonathan D. Mays, 4 September 2022, Ecology.
DOI: 10.1002/ecy.3857