New Zealand has around 1,400 native species of snails and slugs.
Snail or slug?
The main difference between snails and slugs is that snails have a shell. Slugs do not – although some (called semi-slugs) have a small partial shell.
Other features are the same for snails and slugs:
- They move around on a flat, muscular foot.
- They have one or two pairs of tentacles on their heads. The larger pair of tentacles usually has eyes at the end.
- They eat using a tongue-like organ called a radula, covered with rows of teeth.
- Most are hermaphrodites – they have both male and female sex organs.
Most New Zealand native slugs and snails are small and easy to miss. They live in damp litter on the forest floor, and eat the micro-organisms that break down plants. Many species are endangered because their habitats have changed, or predators attack them.
There are three species of flax snail. Despite their name, they do not eat flax. They have a tall shell, up to 8 centimetres high. When they are young, they live in trees. When they get bigger, they move down to the ground.
- Giant kauri snails live in Northland. They eat worms, insects and snails.
- Powelliphanta snails can grow to 10 centimetres across (about the size of a hamburger). They only come out at night to feed on worms and slugs. They have beautiful shells. Their eggs also have a hard pink shell, like a tiny bird’s egg.
There are about 30 native species of slug. Their upper side is patterned to look like a leaf for camouflage, and they eat algae and fungi – tiny organisms that live on plants.
The slugs and snails seen in gardens are usually not native to New Zealand. Many eat plants, and are a pest to gardeners.
Saving Powelliphanta snails
In 2006, some rare Powelliphanta snails were moved from their home on the South Island’s West Coast. A coal company planned to mine the area, so it moved the snails to a new spot. The snails had radio transmitters attached so scientists could keep track of them.