Watch Wild Down Under online: Episode 3 Southern Seas

The third instalment features the wildlife of Australasia's seas and coasts. On Western Australia's desert coastline, seas are lifeless apart from a few fertile pockets. Whale sharks feed close to shore at Ningaloo Reef. At Shark Bay, sharks and dogtooth tuna pin a sardine shoal to the shore, filmed from the air and underwater. A pair of Bryde's whales joins the feeding frenzy. Shallow, sandy bays are ideal conditions for seagrass, browsed by dugongs. In north Australia, monsoon rains flush rich sediment into the ocean. At low tide, golden ghost crabs and mudskippers emerge to feed on the exposed worms, snails and shellfish. The Leeuwin Current brings warm water to the south coast. Australian sea lions and southern right whales raise their young in the impoverished waters of the Great Australian Bight, while giant cuttlefish gather in the breeding season. The cold Southern Ocean skirts Australia's remote south west tip, where the seas are home to giant kelp forests and strange creatures. The leafy sea dragon is camouflaged as seaweed, while the handfish uses its fins to walk across the seabed. At night, female lobsters climb to high points on the reef to release their brood of larvae. In New Zealand's cold and nutrient-rich waters, gannets are filmed plunge-diving into a sardine shoal, which also attracts common dolphins. Hector's dolphins stay close to shore to avoid sharks. Snares Islands penguins must negotiate a steep granite rockface and patrolling Hooker's sealions to reach their nest burrows.

click here to see where to watch or .