Overview
The Ryukyu Giant Amphibious Centipede (Scolopendra alcyona), described to science in 2021 as Japan’s first new centipede species in 143 years, is the largest terrestrial and semi-aquatic centipede in the Japanese archipelago. Named after the Greek mythological sea nymph Alcyone, this colossal, jade-green armored predator hunts with equal ferocious agility on dry rainforest boulders and fully submerged beneath the rushing currents of subtropical mountain streams.
Biology and Physical Characteristics
Reaching over eight inches in length and nearly an inch wide, Scolopendra alcyona is a visual masterpiece of predatory engineering. Its segmented exoskeleton exhibits a dark, polished jade-green to metallic cyan hue, contrasted against 21 pairs of vivid yellow-to-orange banded legs. Its terminal legs are thickened and flattened, acting as aquatic swimming paddles, while its heavy venomous forcipules deliver powerful paralyzing toxins capable of subduing aquatic and terrestrial prey with equal speed.
Behavior and Ecology
Endemic strictly to pristine, undisturbed mountain stream catchments in the subtropical rainforests of Yanbaru on northern Okinawa and nearby islands, Scolopendra alcyona is uniquely amphibious. When hunting or escaping danger, it plunges effortlessly into rushing freshwater pools, swimming with sinuous eel-like undulations across riverbeds to ambush freshwater giant river prawns (Macrobrachium), stream gobies, and riparian frogs. Its hydrophobic cuticle prevents waterlogging, allowing it to transition seamlessly between terrestrial leaf litter and underwater hunting grounds.
Conservation and Human Impact
Listed as Endangered due to its small island distribution and extreme habitat specificity, Scolopendra alcyona was immediately declared a National Protected Species by the Japanese Ministry of the Environment upon its discovery. Primary threats include illegal poaching by international exotic arthropod collectors, deforestation from military training area access roads, and river modification that disrupts pristine boulder-strewn headwater streams. Conservation enforcement in Yanbaru National Park provides critical protection.
Interesting Factoid
This giant eight-inch jade-green centipede was only recently discovered in 2021—it is amphibious and dives straight into rushing jungle rivers like an eel to hunt down swimming freshwater shrimp under rocks!
Last updated: October 2026