Test: Australia- Physical - UPSC MCQ

The defining characteristic of the continent of Oceania is the Pacific Ocean. The name "Oceania" establishes the Pacific Ocean as the defining characteristic of the continent. Oceania is a region made up of thousands of islands throughout the Central and South Pacific Ocean.

New Zealand is not considered a continental island. Continental islands were once attached to continents before sea level changes and tectonic activity isolated them. Australia, Zealandia, and New Guinea are continental islands.

High islands, also called volcanic islands, are created as volcanic eruptions build up land over time. These islands have a steep central peak and ridges and valleys that radiate outward from the peak toward the coastline.

The island regions of Micronesia and Polynesia are dominated by low islands. Low islands, also called coral islands, are made of the skeletons and living bodies of small marine animals called corals.

Species that are found nowhere else on Earth are referred to as endemic species. Due to the isolation of Australia and Oceania from the rest of the world, the region has a high number of endemic species.

The Temperate Australasia realm, which includes the seas surrounding the southern half of Australia and the islands of New Zealand, is known for its rich seabird populations. Its cold, nutrient-rich waters support a diversity of plants and fish that seabirds feed on.

The Great Barrier Reef and the New Caledonia Barrier Reef are considered underwater hotspots for biodiversity in Australia and Oceania. The Great Barrier Reef, located off the coast of northeast Australia, is the largest coral formation in the world.

Australia is home to the world's largest marsupial population. Marsupials, such as koalas, kangaroos, and wallabies, are native to Australia and Oceania. Marsupials are mammals that carry their newborn young in a pouch.

Sea level changes during the last glacial period played a major role in the evolution of flora and fauna across the islands of Australia and Oceania. Lower sea levels allowed for the movement of plants and animals from southern Asia to the islands.

Birds are particularly mobile and play a significant role in seed dispersal between islands in Australia and Oceania. Birds carry the seeds of fruits and plants and spread them between islands through their droppings.