Flightless birds, giant snails, walking bats – many of New Zealand's plants and animals are unique. There are almost no native mammals, but lots of frogs, lizards, wētā and land snails. Some species are similar to plants and animals in the other lands once joined to New Zealand as the Gondwana supercontinent.
This has led to the questions: Where did New Zealand's plants and animals come from? How did they get to New Zealand? Are they different from species elsewhere – and if so, why?
Survivors from Gondwana?
About 85 million years ago, the land that became New Zealand broke away from the eastern edge of Gondwana (which is now eastern Australia). Some of today's plants and animals may have evolved from those living there at this time, although for many species there is little or no fossil evidence.
Many plants and animals have arrived more recently. This helps explain why there are few mammals. Only animals that flew, or were light enough to be carried by the wind, or small enough to arrive on floating material, could cross the ocean between New Zealand and other lands.
There were few predators on the ground, so many birds did not need to be able to fly. Some took on the behaviour and habitats of mammals – for example, kiwi are strong diggers, and nest in burrows.
Plants have developed white, simple flowers to attract as many insects as possible – New Zealand has no native, specialised pollinating insects. The plants did not evolve special features to survive very cold weather, as they did in other countries.
Many of New Zealand's plants and animals were once similar to those in Australia. But as the country drifted into cooler zones and mountains were formed, many species died out or evolved to adapt to the new climate and landscapes.
Many New Zealand plants and animals radiated. Radiation is when a species rapidly evolves into many species, each adapted to different habitats or conditions. For example, 70 species of wētā have evolved. They live in all habitats, from the mountains to the coast.