A new study suggests apparent attacks are actually fleeting cases of mistaken identity
Olive sea snakes are among the largest marine snake species and sometimes make contact with divers.
Numerous scuba divers in places like Australia’s imperiled Great Barrier Reef have reported what they interpreted as unprovoked attacks from venomous sea snakes, especially the olive sea snake which can reach lengths of around six feet. Divers say the snakes, which breathe air but spend their entire lives in the ocean, sometimes come hurtling out of the blue swimming in rapid zig-zags straight at the person. These encounters almost never result in recreational divers getting bitten, but the apparent aggression from animals packing deadly neurotoxic venom is enough to alarm most who experience it firsthand.
Now, new research reveals that these charging sea serpents likely harbor no malice toward the humans visiting their home. Instead, the paper, published today in the journal Scientific Reports, suggests these underwater dust ups are actually cases of mistaken identity, with the understandably shaken divers having been caught in the crossfire of the sea snake’s urgent quest to find love during the winter mating season.
“Wild animals don’t attack people without good reason,” says Rick Shine, evolutionary biologist at Macquarie University in Australia and the study’s senior author. “Snakes on land almost never attack people but there were all these stories about sea snakes doing it. Why the hell would a sea snake race towards a person underwater?”
Shine’s co-author Tim Lynch, a scientist with Australia’s Commonwealth Scientific and Industrial Research Organization, happened to be sitting on an unpublished data set with the potential to answer that very question. Back in 1994, Lynch had spent 250 hours scuba diving around the Keppel Islands in the southern Great Barrier Reef to study olive sea snake behavior for his PhD thesis. Lynch would record how many snakes he encountered as well as whether they approached him and for how long within individual 30-minute periods.
Shine recalls reviewing the completed thesis with interest but the results weren’t published in a peer-reviewed journal at the time. Then, more than 20 years later when the Covid-19 pandemic grounded virtually all field research, Shine approached Lynch about dusting off his data and giving it a fresh analysis.
Shine and Lynch found that out of 158 encounters, 74 included the snake approaching the diver and that these interactions were more common during the olive sea snake’s mating season between May and August. Only 13 of these interactions involved full on charges towards the diver. The onrushing snakes were split almost fifty-fifty by sex, with seven males and six females comprising the group.