Study of Emydocephalus annulatus determined that they stay on their own reef, even if another reef is within swimming distance.
Researchers at the ARC Centre of Excellence for Coral Reef Studies (CoECRS) and The University of Sydney just published a paper on the turtle-headed sea snake (Emydocephalus annulatus) stating that the species rarely ventures off its home reef, and this behavior could lead to its extinction. During the last eight years, turtle-headed sea snakes on two New Caledonian reefs that are within swimming distance of each other were captured, tagged, microchipped and then released back onto the reef.
The snakes were then recaptured on the same reefs over the eight years in which they were tracked, leading the scientists to believe that they remained on the reef in which they were first captured. The findings were backed up by a genetic dataset that determined that sea snakes on one reef were more closely related to each other than those found on the other reef. The scientists speculate that because the turtle-headed sea snake eats eggs from reef fish exclusively, they tend to stay in places where they know where food is rather than go out onto distant reefs in search of food. Scientists say that this behavior makes the sea snakes vulnerable to changes that occur on the reefs in which they live and forage. In fact, they cite the extinction of the snake on Ashmore Reef in the Timor Sea as reason to raise conservation awareness of the species.
The turtle-headed sea snake lives in waters that are less than 32 feet in depth at the edges of lagoons and coral reef outcrops. They can be found on reef flats at high tide, and often in tide pools at low tide. They can spend up to two hours underwater between breaths and have an elongate cylindrical lung that extends nearly the length of its body. They also have a salt excreting gland that helps them avoid excess salt. They shed every two to six weeks and feed exclusively on eggs from reef fish, including blennies (Blenniidae), gobies (Gobiidae) and coral fish (Pomacentridae).
Reference: Sea Snakes Rarely Venture Far from Home DOI: 10.1002/ece3.256