Photographs capturing a battle royale between what may be two of the ocean’s most venomous creatures—a sea snake and what is possibly a stonefish—have gone viral, but such face-offs probably aren't all that rare.
What is rare is for such encounters to be recorded.
An Australian spear fisherman happened upon the sea snake/fish fight last Thursday off Darwin, in northern Australia. He grabbed the animals out of the water for a quick picture, then released them.
"I'm silly but not mad,” the spear fisherman, Rick Trippe, told BBC. “I knew this was dangerous."
Fish are a regular part of the diet of many sea snakes, says John C. Murphy, a sea snake expert at Chicago’s Field Museum of Natural History.
It’s hard to identify the species of sea snake from photos, Murphy says, because the precise scale counts are often needed to distinguish similar types. But he agrees with Trippe that an elegant sea snake (Hydrophis elegans) is a possibility, based on the coloring and location.
It's also difficult to identify the fish. It's possiblly not really a stonefish, as Trippe thought, but actually a species of harmless frogfish, says Bryan Fry, a National Geographic explorer and biologist who studies venom at the University of Queensland.
Both frogfish and stonefish are fairly common in the waters around Australia. The mottled, irregularly shaped fish use camouflage to hide among reefs. But they defer in their strategy for defense. Frogfish often mimic venomous animals, while stonefish boast spines with toxic sacs. The potent venom can kill a person within two hours without treatment, so the fish often pose a hazard to divers, particularly those who walk along the ocean floor.
Both stonefish and frogfish are regularly eaten by sea snakes, and Murphy says it’s unlikely a snake would get stuck by a fish’s venomous spines.
“Sea snakes usually swallow fish head first, so they don’t have to work against the fins,” he says. “The stonefish’s spines, which are in the fins, would lay down against the animal’s body, so I would not expect any of the spines to puncture the snake's tissue.”
It’s also possible that sea snakes are immune to stonefish venom, but Murphy doubts there's any research on the question. Not much is generally known about sea snakes, which live in many parts of the world. Some of them are endangered, a few critically so.
Sea snakes hunt by biting their prey with their small fangs and injecting their venom. Then they hold on tight until the prey becomes subdued and swallow it whole.
“It would not be a nice way to go,” says Murphy.
By witnessing such predator-prey encounters, we get a window into evolution in action, says Zoltan Takacs, a herpetologist and pharmacologist who is the founder of the World Toxin Bank and an explorer with National Geographic.
"This sea snake-fish encounter is a work-in-progress in 'nature's research lab' and this is how future medications are being 'designed,'" says Takacs, who notes that several drugs have been developed from snake venoms, for major diseases from hypertension to heart attack.
"Venom toxins are among the most potent and precision-targeted molecules on Earth," Takacs adds.
Trippe says the sea snake attacked the fish again as soon as he released them back into the water. This time, the snake prevailed.
This story was updated at 9:30 a.m. ET Wednesday to include a discussion about the uncertainty of the kind of fish fighting the sea snake, at 9:00 p.m. ET Tuesday to include Bryan Fry's thoughts, and at 11:30 a.m. ET Wednesday to include Zoltan Takacs' thoughts.