Black-Headed Sea Snake

The black-headed sea snake is notable for occurring at the northern edge of sea snake distribution, reaching temperate coastal waters around southern Japan. Its dark head contrasts with a lighter, banded body.

It is one of relatively few sea snake species adapted to cooler waters outside the fully tropical Indo-Pacific belt, making it of particular interest for studies of sea snake thermal tolerance.

• Distinctly dark, blackish head contrasting with a paler body
• Body pale gray to yellowish with dark crossbands or blotches
• Smooth scales and laterally compressed, paddle-shaped tail
• Small head not markedly distinct from neck
• Head coloration is the key distinguishing feature from similar banded Hydrophis species

Found in coastal and continental shelf waters, including bays and areas near river mouths, from southern Japan and Taiwan through the East China Sea. Tolerates cooler subtropical waters compared to most sea snakes.

Feeds primarily on small fish, hunting along the seafloor and among coastal structures. Fully marine and gives birth to live young in the water. Seasonal water temperature changes in its range likely influence activity and reproductive timing.