what sensory skills does it have?
They have three classes of visual pigments all from cone cells.
Sea snake
sea snakes found three classes of visual pigments all from cone cells. Despite the absence of rod cells in sea snake eyes, Simeos et al. found genes from rod-cells ("rh1") were still being expressed suggesting that in sea snakes some cones may be transmuted rods. 
what is sea snake? A subfamily of venomous elapid snakes, the Hydrophiinae. is its venom used for any research? UNANSWERABLE
wiki:2413651
Sea snake [SEP] Sensory abilities
Shine experimented with applying skin secretions (pheromones) to snake-like objects to see if male turtle-headed sea snakes, "Emydocephalus annulatus," are attracted to female pheromones. Shine found that although vision may be useful over short distances (<1 m), pheromones are more important once the male comes in physical contact with an object. The olive sea snake, "Aipysurus laevis," has been found to have photoreceptors in the skin of its tail, allowing it to detect light and presumably ensuring it is completely hidden, including its tail, inside coral holes during the day. While other species have not been tested, "A. laevis" possibly is not unique among sea snakes in this respect.