The Australasian ecozone covers Australia, New Guinea and the easternmost islands of the Indonesian archipelago, including Sulawesi and the Lesser Sundas. New Zealand is also part of this ecozone.
The boundary between Australasia and Indomalaya follows the Wallace Line, named after the naturalist Alfred Russel Wallace who noted the differences in fauna between the islands either side of the line. The Islands to the west, including Java, Bali, Borneo, and the Philippines share a similar fauna with East Asia, including tigers, rhinoceros, and apes. During the ice ages, sea levels were lower, exposing the continental shelf that links these islands to one another and to Asia, and allowed Asian land animals to inhabit these islands.
To the East, Australia and New Guinea are distinguished by marsupial mammals, including kangaroos, possums, and wombats. The last remaining monotreme mammals, the echidnas and the platypus, are endemic to Australasia. Prior to the arrival of humans about 50,000 years ago, only about one-third of Australasian mammal species were placental.
Broadleaf forests are the dominant habitat of the UK and most of temperate northern Europe. There's little left of Britain's ancient wildwood, but isolated pockets of oak, beech and mixed deciduous and evergreen woodlands are scattered across the continent, and dictate its biodiversity.
Coastal cliffs are the rocky land edges that face the sea. These are complex and diverse habitats that lie above the water line, where exposure to salty spray, wind, sun and rain all play their part, as does the type of rock.
Desert and dry scrubland describes any area that receives less than 250mm of rainfall a year. Not just the endless, baking sand dunes of popular conception, it includes arid areas in temperate regions.
Mangrove forests grow on tropical coasts with soft soils and are flooded twice daily by the tide. They are important nursery areas for many species of fish.
Mediterranean forest includes the fynbos of South Africa, the matorral of Chile and forests in parts of California. Hot, dry summers, contrast with much milder, wetter winters.
Mountain grasslands such as those in the Ethiopian highlands, on the Tibetan Plateau and up in the Andes, include the alpine tundra above the treeline as well as grasslands below it. These high altitude grasslands often exist as isolated 'islands' in a sea of another habitat type.
Rainforests are the world's powerhouses, the most vital habitats on the planet. Characterised by high rainfall, they only cover 6% of the Earth across the tropical regions, but they contain more than half of its plant and animal species.
Temperate grasslands include the prairies of North America, the steppes of Russia and the pampas of Argentina. Summers here are mild to hot and the winters can sometimes be very cold – for instance, blizzards can blanket the great plains of the United States.
Tropical dry forests, in contrast to rainforest, have to survive a long dry season each year, so the predominantly deciduous trees shed their leaves to cope with it. Sunlight can then reach the ground, so the season that's bad for the trees is good for the forest floor.
Tropical grasslands include the savanna usually associated with Africa, and savanna-type grasslands found in India, Australia, Nepal and the Americas. They are characterised by drought-resistant shrubs and grasses, dotted with trees such as acacias or baobabs.
Tundra is the cold, treeless region around the poles that has permafrost as one of its defining features. Even at the height of summer, the soil a few centimetres under the surface remains frozen.