Research press release


Scientific Reports

Biology: Sea snake attacks may be misdirected courtship behaviours

有毒なオリーブウミヘビ(Aipysurus laevis)がスキューバダイバーを攻撃するのは、相手を誤認した求愛行動だとする見解を示した論文が、Scientific Reports に掲載される。


今回、Rick Shineたちは、1994~1995年に収集されたデータ(論文著者の1人であるTim Lynchがオーストラリアのグレートバリアリーフでダイビングをしていた時に遭遇したオリーブウミヘビの行動について記述したデータ)を分析した。Lynchは、ウミヘビに158回遭遇し、そのうちの74回でウミヘビが近づいてきた。この行動は、5~8月の交尾期に頻繁に起こっていた。特に交尾期には、雄のウミヘビは、雌よりも頻繁にダイバーに接近し、ダイバーの体の近くで、舌をチロチロと出し入れした。また、13回の遭遇では、ウミヘビが急に突進してくる攻撃があった。全ての攻撃は、交尾期に起こっており、雄による攻撃は、雌の追跡に失敗した直後や雄のライバルとの相互作用の直後に生じることが観察された。また、3匹の雄がダイバーの足ヒレに巻き付く行動をとったことも観察された。このように巻き付く行動は、通常、求愛中に観察されている。雌による攻撃は、雄に追跡された後に起こり、あるいは雄を見失った後にダイバーに接近したというものだった。


Attacks by venomous Olive sea snakes on scuba divers may be misdirected courtship behaviours, according to a study published in Scientific Reports.

Scuba divers frequently report unprovoked attacks by sea snakes, which can involve chasing and biting. The reasons for these attacks have been unclear.

Rick Shine and colleagues analysed data collected between 1994 and 1995 describing Olive sea snake behavior during encounters with one of the authors, Tim Lynch, when he was a diver in the Great Barrier Reef, Australia. The researchers found that sea snakes approached the diver during 74 out of 158 encounters and that this occurred more frequently during mating season – between May and August. Males were more likely than females to approach the diver, especially during mating season, and to flick their tongues near the diver’s body. 13 encounters involved sea snakes rapidly charging at the diver. The authors observed that all charges occurred during mating season and that those involving males occurred immediately after an unsuccessful chase of a female, or an interaction with a male rival. Three males were also observed coiling around the diver’s fin, a behavior usually observed during courtship. Charges by females occurred after they were chased by males or lost sight of, and then re-approached, the diver.

Previous research has suggested that sea snakes find it difficult to identify shapes in water. The authors suggest that sea snake attacks may be caused by male sea snakes mistaking a diver for a rival snake or potential mate and female sea snakes perceiving a diver as a potential hiding place. By staying still and allowing a sea snake to investigate them with its tongue, a diver is unlikely to escalate the encounter and be bitten, according to the authors.

doi: 10.1038/s41598-021-94728-x


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