Sea snake approaches to divers

Scuba-divers on tropical coral-reefs often report unprovoked “attacks” by highly venomous Olive sea snakes (Aipysurus laevis). Snakes swim directly towards divers, sometimes wrapping coils around the diver’s limbs and biting. Based on a focal animal observation study of free-ranging Olive sea snakes in the southern Great Barrier Reef, we suggest that these “attacks” are misdirected courtship responses. Approaches to divers were most common during the breeding season (winter) and were by males rather than by female snakes. Males also made repeated approaches, spent more time with the diver, and exhibited behaviours (such as coiling around a limb) also seen during courtship. Agitated rapid approaches by males, easily interpreted as “attacks”, often occurred after a courting male lost contact with a female he was pursuing, after interactions between rival males, or when a diver tried to flee from a male. These patterns suggest that “attacks” by sea snakes on humans result from mistaken identity during sexual interactions. Rapid approaches by females occurred when they were being chased by males. Divers that flee from snakes may inadvertently mimic the responses of female snakes to courtship, encouraging males to give chase. To prevent escalation of encounters, divers should keep still and avoid retaliation.

Methods
A diver recorded interactions with free-ranging snakes.

热带珊瑚礁海域的水肺潜水者常报告遭遇到高毒性橄榄海蛇（Aipysurus laevis）的无端“攻击”。此类海蛇会径直游向潜水者，有时会以躯体缠绕其肢体并发起撕咬。基于对大堡礁南部自由活动的野生橄榄海蛇开展的定点动物观测研究，我们提出：这类所谓的“攻击”实为定向错误的求偶反应。

潜水者被海蛇接近的频次在繁殖期（冬季）达到峰值，且实施接近行为的均为雄性海蛇，而非雌性。雄性海蛇还会反复发起接近动作、在潜水者附近停留更久，并展现出仅在求偶行为中观察到的典型动作（如缠绕肢体）。当求偶中的雄性失去与其追逐的雌性的联系、与雄性竞争者发生互动，或是潜水者试图逃离雄性海蛇时，常会出现雄性海蛇躁动且快速逼近的行为，这类表现极易被误判为“攻击”。雌性海蛇的快速逼近行为则多发生在自身被雄性追逐之时。若潜水者逃离海蛇，可能会无意间模仿雌性海蛇对求偶行为的应答反应，进而促使雄性海蛇持续追击。为避免互动升级，潜水者应保持静止，切勿进行反击。

研究方法
一名潜水员记录了其与自由活动野生海蛇的互动过程。