Our micro snails are world champions

OPINION favoured exotic pet in the US where they sell for upwards of $200.

Madagascar is also home to 101 species of lemur. All these lemurs evolved from a common ancestor that arrived on the island about 50,000 years ago.

The island once had 17 more species, one the size of an adult human. Unfortunately for them, the earliest people to reach Madagascar ate these 17 lemurs to extinction. Loggers threaten today’s 101 species. As do slash and burn farmers, Madagascans looking for something to eat, or to trade on the pet market.

Native New Zealand hebes (known to botanists as veronicas) are a diverse lot. One species found its way here more than two million years ago that evolved into today’s 100-odd species, many confined to certain mountain ranges. Biologists call this evolutionary process ‘‘adaptive radiation’’.

Another peculiar place is Lake Victoria in Africa. Three perchlike fish found their way into the lake between 10,000 and 15,000 years ago and have since evolved into more than 500 species.

Lake Victoria’s attractive little fish are of every colour, and patterned with every kind of stripe and spot. They are aquarium favourites, which is why we see so many of these cichlid fish in dentists’ waiting rooms.

There is a freaky situation in Hawaii, which is home to more than 800 kinds of the fruit fly Drosophila. Because of distinctive patterns on their wings the island insects are known as ‘‘picturewinged’’ flies. In mind-numbing exercises, DNA experts have elucidated the evolutionary history of these flies. They think three species of fruit fly arrived in Hawaii 30 million to 40 million years ago and they evolved into today’s 800 species. And they are still evolving into new species on some islands.

Scoop up an armful of leaf litter from the floor of the New Zealand bush and you’ll probably scoop up about 30 sorts of snails. Not big snails, but tiny snails the size of a pinhead or up to 8mm across. Rotting New Zealand leaf litter is unlike any other litter in the world, providing a home for at least 450 named species of these tiny snails. As many as 95 different species live in the bush near Auckland, and 88 species in the bush near Wellington.

Generations of snail specialists – malacologists – have been driven nearly mad sorting through our tangle of micro snails, carefully measuring, describing, and giving them Latin names. Wherever they look, experts find more species and reckon another 500 species have yet to be discovered.

With something like 1000 species of micro snails, New Zealand bush has perhaps the most diverse animal assemblage in the world.