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The colubrine sea krait, banded sea krait or yellow-lipped sea krait (Laticauda colubrina) is a species of venomous sea snake found in tropical Indo-Pacific oceanic waters.

Description

Ventrals are large, one-third to more than half the width of the body; nostrils are lateral; nasals are separated by internasals; 21-25 longitudinal rows of imbricate scales are found at midbody; an azygous prefrontal shield is usually present; and the rostral is undivided.

The body is subcylindrical, only slightly compressed. The rostral is higher than broad; an azygous shield separates the prefrontals, but sometimes is absent; the frontal is considerably longer than its distance from the end of the snout; one preocular and two postoculars are present; with 7-8 supralabials, the 3rd-4th touch the eye temporals 1+2 ; five infralabials are in contact with the genials, both pairs of which are usually well developed and in contact with one another, the anterior pair is smaller than the posterior; a double series of elongated scales, the inner series the larger, occur at the oral margin. Scales are in 21-23 rows (rarely 25). Ventrals number 213 to 245, and are about four times as long as broad. Subcaudals in males number 37-47, and in females 29-35.

Total length: males 875 mm, females 1420 mm; tail length: males 130 mm, females 145 mm. In colour these snakes are light or dark bluish grey above, yellowish below, with black bands more or less of uniform width throughout or narrowing on the belly (some of them interrupted below). Upper lip yellow. Snout yellow, the colour extending backward on each side of the head on each side of the head above the eye as far as the temporal shields, leaving a dark bar in between. Rest of the head is black. They are venomous but are not aggressive to divers.

Biology

Banded sea kraits are often seen in large numbers in the company of hunting parties of giant trevally (Caranx ignobilis) and goatfish. Their cooperative hunting technique is similar to that of the moray eel, with the kraits flushing out prey from narrow crevices and holes. Kraits need to drink fresh water and regularly come onto land for that purpose.

While probing crevices with their head and thus unable to observe approaching predators, banded sea kraits can fool their potential enemies to believe that their tail is the head. This is based on both colouration and tail movements, such that the lateral aspect of tail corresponds to the dorsal view of the head.

Observation and nesting

Banded sea kraits rest and nest on rocky headlands and beaches of Sabah, Borneo. They can be seen in the wild at Pulau Tiga, the tip of Borneo and Mabul Island. They are, however, seen on many other rocky headlands around Sabah that are harder to access. Occasionally, they come ashore at Tanjung Aru close to Kota Kinabalu. They can be seen in captivity at The Green Connection, an aquarium in Kota Kinabalu.

The males come ashore early in the evening and wait at the high tide line for the females. Females are much larger and many males will escort and intertwine around a single female.

There are fewer recorded bites from this species compared to other venomous species such as cobras and vipers as it is less aggressive and tends to avoid humans. If they bite, it is usually in self-defence when accidentally grabbed. Many fishermen are bitten each year when they try to clear sea snakes from their nets.

Distribution

Banded sea krait is a widespread species in eastern Indian Ocean and Western Pacific. It is found from eastern coast of India east through

coasts of Bay of Bengal (Bangladesh, Mayanmar) and SE Asia to Malay Archipelago and to southern China, Taiwan, and the Ryukyu Islands of Japan. Vagrant individuals have been recorded in Australia, New Caledonia, and New Zealand.

Parasites

Banded sea kraits when collected near the tip of Borneo had heavy tick infections.

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