The turtleheaded sea snake is a fully aquatic species, spending its entire life in the water (7). Despite being an air-breathing animal, the turtleheaded sea snake is capable of remaining underwater for up to two hours before surfacing to breathe again, and it has specialised valves which prevent water from entering the nostrils when the snake is submerged. Its single, elongated lung, which extends for almost the entire length of its body, is highly efficient for gas exchange, and sea snakes are also able to absorb oxygen through their skin when underwater. As in other sea snake species, the turtleheaded sea snake has a specialised gland under its tongue which enables it to excrete excess salt from its body (3).
Unusually among sea snakes, the turtleheaded sea snake shows complex social behaviour, often moving about in distinct groups. It also demonstrates high site fidelity, with the same individuals being found repeatedly within small home ranges on coral reefs (1) (3). The turtleheaded sea snake is not an aggressive species, and when confronted by a predator it tends to hide in reef crevices rather than strike back at its attacker. Although venomous (5), the turtleheaded sea snake only has tiny fangs, less than one millimetre in length (2), and its venom is one of the weakest among sea snake species (2) (9).
The turtleheaded sea snake does not require large fangs or potent venom as its diet consists solely of fish eggs (2) (3) (4) (6) (7) (9). This species mainly forages during the day (4), slowly moving among corals and investigating crevices or burrows for fish nests containing egg masses (2) (3) (10). The eggs on which it feeds are tiny (7) (10), and the turtleheaded sea snake feeds frequently, sometimes several times per hour (10). This species is thought to locate its food by scent (3) (10), and once an egg mass is found the turtleheaded sea snake scrapes the eggs off the substrate using an enlarged scale on its jaw, which functions much like a blade (1) (2) (3) (4) (7). The turtleheaded sea snake is known to consume the eggs of various fish species, particularly those of damselfish, blennies and gobies (1) (3) (7).
Male turtleheaded sea snakes tend to swim more rapidly than females, and a male will actively court any female it encounters (7). Little is known about the specific reproductive habits of the turtleheaded sea snake (2), although like most species of sea snake it is known to be viviparous, which means that it gives birth to live young rather than laying eggs (2) (3) (7). The female turtleheaded sea snake is thought to produce two to five young in each litter (3).