How to Identify the Rough-Scaled Sea Snake (Identification Guide)

Key identifying features

The Rough-Scaled Sea Snake (Hydrophis curtus, formerly Lapemis curtus or Lapemis hardwickii) stands out among sea snakes for its notably rough body texture. Unlike the smooth, glossy scales typical of most marine snakes, this species has heavily keeled scales, often with small spines or ridges, that give the skin a dull, grainy appearance rather than a shiny one. This texture is often visible even from photographs and is a key confirming feature alongside its stout build.

Coloration & pattern

Coloration is variable but usually consists of a grayish, olive, or pale yellowish-gray background marked with a series of darker gray or brown crossbands or diamond-shaped blotches along the back. These markings can be bold and well defined in some individuals and faded or nearly absent in others, particularly in older adults, which may appear almost uniformly pale gray or olive. The belly is generally lighter, often pale yellow or cream.

Head, eyes & scales

The head is moderate to relatively broad, not tiny like some burrowing sea snakes, with large symmetrical shields on top. Eyes are moderate sized with round pupils. The most diagnostic feature is scalation: body scales are strongly keeled, often bearing small tubercle-like projections, especially pronounced in males, creating a bristly or sandpaper-like texture distinct from the smooth scales of most other sea snakes in the region.

Size & body shape

Adults commonly reach 60 to 100 centimeters, with a thickset, robust body that is notably stout compared to more slender sea snake species. The body does not taper dramatically and maintains a heavy, muscular build along most of its length before narrowing into a compressed paddle tail. This combination of a stocky build and rough scale texture makes the species feel and look markedly different from sleeker sea snakes even when coloration is faded.

Range & habitat where you'll see it

This species is widespread across the Indo-West Pacific, from the Persian Gulf through South and Southeast Asian coastal waters to northern Australia. It favors turbid, shallow coastal waters, estuaries, and muddy or sandy bottoms, and is one of the more commonly encountered sea snakes in trawl bycatch due to its abundance in these habitats.

How to tell it apart from look-alikes

The rough, keeled, almost spiny scale texture combined with a stout body shape is the clearest distinguishing combination from other banded sea snakes, most of which have smooth, glossy scales. When markings are faded and coloration alone is unreliable, examining close-up photographs for scale texture and body girth remains the most dependable way to separate this species from smoother-scaled relatives with similar banding.