Hydrophiinae in the context of Pseudonaja

Sea snakes, or coral reef snakes, are elapid snakes that inhabit marine environments for most or all of their lives. They belong to two subfamilies, Hydrophiinae and Laticaudinae. Hydrophiinae also includes Australasian terrestrial snakes, whereas Laticaudinae only includes the sea kraits (Laticauda), of which three species are found exclusively in freshwater. If these three freshwater species are excluded, there are 69 species of sea snake divided among seven genera.

Most sea snakes are venomous, except the genus Emydocephalus, which feeds almost exclusively on fish eggs. Sea snakes are extensively adapted to a fully aquatic life and are unable to move on land, except for the sea kraits, which have limited land movement. They are found in warm coastal waters from the Indian Ocean to the Pacific and are closely related to venomous terrestrial snakes in Australia.

The tiger shark (Galeocerdo cuvier) is a species of ground shark, and the only extant member of the genus Galeocerdo and family Galeocerdonidae. It is a large predator, with females capable of attaining a length of over 5 m (16 ft 5 in). Populations are found in many tropical and temperate waters, especially around central Pacific islands. Its name derives from the dark stripes down its body, which resemble a tiger's pattern, but fade as the shark matures.

The tiger shark is a solitary, mostly nocturnal hunter. It is notable for having the widest food spectrum of all sharks, with a range of prey that includes crustaceans, fish, seals, birds, squid, sea turtles, sea snakes, dolphins, and others, even smaller sharks. It also has a reputation as a "garbage eater", consuming a variety of inedible, man-made objects that linger in its stomach. Tiger sharks have only one recorded natural predator, the orca. It is considered a near-threatened species because of finning and fishing by humans.

Emydocephalus is a genus of sea snakes, also known as turtle-headed sea snakes, in the family Elapidae. The genus is one of a small group of the viviparous sea snakes (Hydrophiinae: Hydrophiini) with Aipysurus. Unlike most sea snakes, the species that make up Emydocephalus lack teeth on their dentary and palatine bones. They also lack venom, making them the only non-venomous elapids. The dentary and palantine bones bear only a row of papillae. Emydocephalus does, however, bear fangs and many small pterygoid teeth. This reduced dentition is due to their diet consisting almost entirely of fish eggs. Due to their prey being small and immobile, they exhibit a foraging strategy different from most snakes, where they forage more frequently but consume smaller quantities.