Marine snakes in general exhibit a range of adaptations to their aquatic environment, of which the ability to stay submerged for long periods of time is particularly remarkable. They are able to avoid frequent trips to the surface to breathe because not only do they have a long, cylindrical lung that runs almost the length of their body, but they are also able to diffuse oxygen from the water through their skin (4). Although in sea kraits this form of respiration is less efficient than in other marine snakes (3), the Rennell Island sea krait frequently remains submerged for more than eight minutes (5). It forages in fairly shallow waters from a depth of only a few centimetres down to a recorded 13 metres. With frequent tongue flicking, it investigates crevices and holes, and the edges of submerged logs and branches for small fish, such as the native goby Eleotris fusca. Like many other marine snakes, this species has a potent venom, which it secretes from hollow fangs at the front of its mouth, and uses to immobilise prey before swallowing (3) (5).
While sea kraits are the only group of marine snake considered to be oviparous, that is, laying eggs instead of giving birth to live offspring, the mode of reproduction has never been reliably recorded in the Rennell Island sea krait (3) (5). Furthermore, local people maintain that in contrast with other Laticauda species, the Rennell Island sea krait does actually give birth to live young (5). Although the other sea krait species are all amphibious, an essential trait for oviparous snakes that must come ashore to lay their eggs (4), during the only field study conducted on this species it was never seen on land (5).