sea snake, commonly known as the yellow-bellied sea
snake, yellowbelly sea snake, or pelagic sea snake, is a species of sea snake found in tropical oceanic waters around the world. It is the only member of the genus Pelamis.
The body of this snake is compressed, posteriorly more than twice the diameter of the neck; the body scales are juxtaposed, subquadrangular in shape, and in 49–67 rows around thickest part of body; ventral scales, 264–406 in number, are very small and, if distinct, divided by a longitudinal groove, but usually are indistinguishable from adjacent body scales.
The head is narrow, with an elongated snout; head shields are entire, nostrils are superior, and nasal shields are in contact with one another; the prefrontal scale is in contact with second upper labial; one or two preoculars, two or three postoculars, and two or three small anterior temporals are present; seven or eight upper labials are found, with four or five below the eye, but separated from the border by a subocular.
Colors of the snake are variable, but most often distinctly bicolored, black above, yellow or brown below, with the dorsal and ventral colors sharply demarcated from one another; ventrally, there may be a series of black spots or bars on the yellow or brown background, or the yellow may extend dorsally so there is only a narrow middorsal black stripe, or a series of black crossbars (M.A. Smith, 1943: 476–477, gives more complete descriptions of the color pattern variants).
Total length for males is up to 720 millimetres (28 in), for females up to 880 millimetres (35 in); tail length for males is up to 80 millimetres (3.1 in), females up to 90 millimetres (3.5 in).
The yellowbelly is the most widely distributed sea snake and is capable of living and giving birth entirely in the open sea (it is totally pelagic), being found in all coastal waters around the rim of the Pacific Ocean except Alaska south to southern California, and in the coastal waters of the Indian Ocean from the Persian Gulf eastwards.
It is the only sea snake to have reached the Hawaiian Islands.[5] The sea snake has also been reported around the shores of New Zealand,[6] a country that would otherwise be free of snakes were it not for the infrequent visits of yellowbellies and banded sea kraits.