Tiger Keelback

Fascinating facts about the Tiger Keelback

• Across East Asia, from Russia’s Primorskiy coast to the Ryukyu Islands, the snake is found.
• When it eats poisonous toads, the snake stores the toads’ cardiotonic steroids in two neck glands, then re-uses those toxins to deter predators, a chemical shortcut known as kleptotoxism.
• At cooler temperatures the tiger keelback flattens its neck and stays motionless, relying on its stored toxins, but when it’s warm it prefers to sprint away, illustrating a temperature-driven switch in defense tactics.
• Its fangs sit at the back of the mouth, so even though it’s venomous, it rarely strikes humans; the combination of rear-fanged anatomy and toxin-laden neck glands keeps fatal encounters exceptionally rare.

At a glance

About the Tiger Keelback

The tiger keelback, Rhabdophis tigrinus, is a strikingly patterned colubrid that glides through the wetlands of East and Southeast Asia with an olive-drab green dorsum punctuated by bold black and bright orange crossbars that run from the neck down the first third of its body, while its belly remains a clean whitish hue. Adults typically measure 60–100 cm in total length, their rear-positioned fangs hidden beneath a sleek head that belies a potent oral venom, though encounters rarely end in fatal bites because the snake often opts for other defensive tactics. Its range stretches from the Primorskiy and Khabarovsk territories of eastern Russia through the Korean peninsula, across the vast heartlands of China (excluding the western third and extreme south), onto Taiwan, Vietnam, and the Japanese archipelago, including Yakushima, Tanegashima, Kyūshū, Shikoku, Honshu, Osaka, and the Ryukyu Islands, where the type locality is simply recorded as “Japan.” When hunting, the tiger keelback relies on both chemical and visual cues to locate its preferred prey of small vertebrates, especially frogs and toads. Remarkably, it sequesters cardiotonic steroids (bufadienolides) from these toxic amphibians in specialized nuchal glands on the back of its neck, a defensive arsenal known as kleptotoxism. Females even pass these sequestered chemicals to their offspring via egg yolk and oviductal transfer, ensuring the next generation inherits a chemical shield. At cooler temperatures the snake adopts a passive stance, flattening its neck and remaining motionless, while warmer conditions prompt a more active flight response, illustrating a temperature-dependent balance between toxin display and escape.

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