Snake Identifier
Small-Headed Sea Snake (Hydrophis gracilis)
Hydrophis gracilis, cropped by A. C. Tatarinov, via Wikimedia Commons, licensed under CC0
Sea snakes

Small-Headed Sea Snake

Hydrophis gracilis

A slender sea snake with a strikingly tiny head and narrow forebody widening toward the rear, found in shallow coastal waters across the Indo-Pacific.

Adult length
0.9-1.2 m (3-4 ft)
Range
Indo-Pacific coastal waters, from the Persian Gulf to Southeast Asia and northern Australia

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Overview

The small-headed sea snake is a marine elapid distinguished by its extremely small head and slender, cord-like neck, which contrast with a noticeably thicker hind body. It is widely distributed in shallow coastal waters across the Indo-Pacific.

As with other members of this diverse marine elapid group, it is fully adapted to aquatic life, with a flattened paddle-like tail. Its distinctive body proportions make it one of the more recognizable of the true sea snakes.

How to identify it

  • Very small, narrow head on a thread-like, slender neck and forebody
  • Body thickens noticeably toward the rear, giving an uneven profile
  • Pale grey or olive coloration with darker crossbands or blotches along the body
  • Smooth body scales in regular rows
  • Laterally compressed tail adapted for swimming
  • Adults generally reach 0.9-1.2 m in length

Habitat & range

Found in shallow coastal and estuarine waters over soft sediment across the Indo-Pacific, from the Persian Gulf and coastal India through Southeast Asia to northern Australia. Prefers turbid, soft-bottomed areas near river mouths where slender, burrow-dwelling prey is abundant.

Behavior, diet & reproduction

Uses its small head and slender neck to probe burrows and crevices in the seabed for eel-like fish and other elongated prey. Active both day and night depending on local conditions. Reproduction is ovoviviparous, with live young born at sea.

Frequently asked questions

Where does the small-headed sea snake live?

It occurs in shallow coastal waters across the Indo-Pacific, from the Persian Gulf to Southeast Asia and northern Australia.

How big does the small-headed sea snake get?

Adults typically reach 0.9-1.2 m (3-4 ft) in length.

What is distinctive about its appearance?

It has an unusually tiny head and slender forebody that widens toward a thicker rear body.