Volunteers at a recent planting day held in a lowland reserve in Horowhenua that is home to a small Powelliphanta population, a native snail.
Volunteers at a recent planting day held in a lowland reserve in Horowhenua that is home to a small Powelliphanta population, a native snail.
Unlike the common garden snail, which demolishes vegetable gardens, New Zealand's native land snails are meat eaters.
Among these are at least 16 species and 57 sub-species of Powelliphanta — which represent some of the most distinctive invertebrates in New Zealand.
If you had Powelliphanta in your backyard, your lettuceplants would be safe but worms and slugs would not.
Powelliphanta traversi sub-species are found throughout Horowhenua
In November 2017, volunteers from Forest and Bird and Fonterra joined DOC rangers for a planting day in one of the Horowhenua swamp forests. The purpose of this mahi is to restore the native vegetation and provide more suitable habitat for the resident Powelliphanta population.
New Zealand's Powelliphanta land snails are as representative of New Zealand's unique evolutionary history as the kakapo, moa or kiwi. Unfortunately, they are also one of the most threatened of New Zealand's invertebrates. Like many of our taonga species, the main threats facing them are predation and habitat loss.
Powelliphanta marchanti is the species of native snail found in the Ruahine ranges.
There are small, scattered populations of Powelliphanta snails throughout New Zealand.
Most are found in the South Island, but they can be found locally in some of the lowland swamp forests of the Horowhenua plains and in the tussock grasslands of the Ruahine ranges.
Very few people get to see Powelliphanta in the flesh. They need moist conditions and live buried in leaf mould or under logs. Powelliphanta usually only venture out at night to forage for food or mate. You are more likely to see an empty shell than a live snail.
Powelliphanta are quite striking to look at, with large flat shells that range from rich brown to gold in colour. Like many snails, they possess both male and female reproductive organs and therefore can mate with any other adult Powelliphanta.
They lay about 5-10 large eggs a year. Each egg is up to 12mm long, pearly pink and hard-shelled — like a small bird's egg.
It is estimated that Powelliphanta snails can live up to 20 years. In snail terms, that is an incredibly long life span.
Powelliphanta are mostly "spot endemics". This means each species and subspecies is confined to its own small area, with lots of country in between without any Powelliphanta at all. This is probably due to the lack of suitable habitat, and the fact that they can't move very fast or far.
Kelly Hancock is a community ranger/ kaitiaki, ao hapori with the Department of Conservation/Te Papa Atawhai in the Manawatu District.
