T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network


Snail (NZ Native Giant land snail) Powelliphanta species.

Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
(unranked): Pulmonata
Family: Rhytididae
Genus: Powelliphanta
Species: Powelliphanta
Common names: Travers land snail, Mount Augustus snail, Paryphanta snail, Kauri snail, Giant snail.

The powelliphanta snails are a species of large, carnivorous land snails and are the largest in the world. The largest species is Powelliphanta superba prouseorum, found in Kahurangi National Park and measuring about 90mm across and weighs in at 90g. There are at least 21 species and 51 sub-species of Powelliphanta, all of which are listed by the New Zealand Department of Conservation as nationally endangered but the threat status varies between species. They are among our most threatened invertebrates.

They are found in native forests through out New Zealand, especially around north–west Nelson and north Westland where they have been the centre of controversy. The species Powelliphanta augustus whose habitat was above a coal seam on Mt Augustus, West Coast. 6000 were collected for relocation and placed in a fridge in Hokitika where a technical fault with a thermostat killed 800 of them.
The powelliphanta snails main predators are possums, pigs and rats. Habitat loss is also another factor in their decline. Possums only recently developed a taste for the snails, and appear to be incorporating them into their diet over increasing areas. The periodic use of the biodegradable poison 1080 to kill possums has reversed the decline in snail populations.
Different species can be found from sea level to above the bushline. The alpine species can contend with prolonged snowfalls and bitterly cold winters. Their usual daytime habitat is under damp leaf mould or under logs. They are usually nocturnal but sometimes forage during the daytime if there is dull damp conditions.

Their favourite prey is earthworms which they suck out of the soil like spaghetti.  See video link:  


The powelliphanta snail's shells come in many sizes, patterns and colours which range from hues of red and brown to yellow and black. 
They are hermaphrodites meaning they have 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 oval egg is up to 12-14mm long, pearly pink and hard-shelled and their dimensions are seldom constant. It is estimated that Powelliphanta snails can live up to 20 years.  

Photo below is of a
 Powelliphanta traversi traversi.which is today restricted to the northeastern shores of Lake Papaitonga, the Waiopehu Scenic Reserve and a few fragments of trees in and around Levin city (a total area of about 40 ha).  

The photo below is of a Powelliphanta patrickensis found in the ranges of the Northern Westcoast of the South Island.Photographed on the Denniston plateau, Papahaua Range. Westland.