A Black-browed Albatross. Albatrosses are the largest of the sea-birds.

The oceans along the meridian line are home to a diversity of habitats and wildlife. Inshore habits like estuaries, mudflats and mangroves offer feeding and roosting areas for birds, and provide sheltered nursery areas for fish and shellfish.Offshore, fish species like tuna, toothfish and sharks, and birds like albatross and petrels patrol the vast oceanic expanses.

Phytoplanton (the marine equivalent of terrestrial grasslands), seaweeds and seagrasses form the base of the food web. In the Southern Oceans the stark seasonality provides a bounty of plant and animal plankton. The estimated production of phytoplankton in the surface waters of the Southern Ocean is 610 million tonnes a year.

Humpback Whale breaching in the waters off Alaska

Zooplankton (the marine equivalent of insects) feed on the phytoplankton and support abundant schools of squid, fish, and consequently a variety of larger marine creatures like seals, seabirds and whales. Half the zooplankton in the Southern Ocean are krill, a shrimp-like animal. Several species of filter feeding whale, like humpbacks, feed directly on krill. In 1994 the Southern Ocean was declared a sanctuary for the great whales.

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Top photo: A Sutter/WWF UK
Side photo: P Coppi/WWF UK