Snail (Kauri snail) Paryphanta genus
informal group Sigmurethra
Species: Paryphanta busbyi, Paryphanta watti
Common name: Kauri snail, pupu rangi
Kauri snails only exist only in northern New Zealand, although they do have carnivorous cousins in Tasmania and Victoria. Once widespread through Northland, the kauri snail now has a limited distribution in parts of Northland and on a few offshore islands.
There are two species:
Paryphanta busbyi—up to 79 mm shell diameter, distribution from Kaitaia south (Northland only)
Paryphanta watti—up to 62 mm shell diameter found only in northern Northland (Te Paki).
Although they are called a kauri snail, this snail doesn't particularly like being around kauri trees because the ground is often too dry for its favourite food—the earthworm. Kauri snails inhabit moist areas of forest and native scrub. They live in areas of high soil fertility and abundant earthworms. Kauri snails are also highly mobile, and have been known to move 10 metres in 2 weeks. The rich brown coloured shells are up to 75 mm across and they are shaped like a flattened spiral.
The kauri snail is carnivorous and cannibalistic. The kauri snail comes out at night to feed on earthworms, insects, insect larvae, slugs and small snails. It envelops its prey, suffocating and crushing it as it withdraws it back into its shell. It then devours its meal with the help of its tongue-like radula. This looks like a ribbon covered with thousands of tiny rasping teeth.
Mating appears to be triggered by climatic conditions, such as rainfall, and can last for 10 hours or more. Hard, limy-shelled eggs of about 13mm long are deposited in nests under leaf mould of the forest floor. On hatching snail hatchlings spend an unknown period living in trees and shrubs up to 6 metres above the ground. Giant snails may live 20 years or more.
Kauri snails were once widespread in Northland before human settlement altered or destroyed their habitat. The main problem today is predation by introduced animals (possums, rats, pigs). 1080 poison helps native snails as possums cause massive problems for New Zealand's native species. The periodic use of the biodegradable poison 1080 to kill possums has reversed the decline in snail populations.
Conservation efforts by the Department of Conservation in the management of kauri snail colonies have been carried out since the early 1980s. Most of this management has consisted of poisoning rodents, enhancement planting, fencing colonies, and stock control. These actions have successfully allowed some species of kauri snails to recover from near extinction to colonies of some hundreds.
Translocations of kauri snails have led to the establishment of populations at Awhita Peninsula, Kaimai Ranges, Waitakere Ranges, and Warkworth. Captive breeding has so far resulted in limited success.
Their favourite prey is earthworms which they suck out of the soil like spaghetti. Watch video below