Kauri snail
Kauri snails/Pupurangi (Paryphanta spp.) belong to the group of northern giant land snails, which contains some of New Zealand's largest snails.Facts about kauri snail
There are more than one species of kauri snail:
- Paryphanta busbyi - up to 79 mm shell diameter, distribution from Kaitaia south (Northland only)
- Paryphanta watti - up to 62 mm shell diameter, distribution: northern Northland (Te Paki)
These giants were once widespread in Northland before human
settlement. Many of them are now endangered or threatened, and inhabit
a more restricted area of Northland and the islands offshore.
Interesting ecology
- Giant snails may live to 20 years or more.
- Mating appears to be triggered by climatic conditions, such as rainfall, and can last for 10 hours or more.
- Snail hatchlings spend an unknown period living in trees and shrubs up to 6 metres above the ground.
- The kauri snail is carnivorous and cannibalistic. Its diet consists of earthworms, insects, insect larvae, and snails.
- Kauri snails are also highly mobile, and have been known to move 10 metres in 2 weeks.
Habitat
Kauri snails inhabit moist areas of forest and native scrub. They live in areas of high soil fertility and abundant earthworms.Threats to kauri snail
The causes of decline for kauri snails include:
- Habitat destruction - caused by humans
- Habitat modification - caused by domestic and feral grazers
- Predation - by introduced animals and birds.
- Collection of live animals for their shells may once have had an effect on population size.
Octopus/wheke
The octopus is the greatest escape artist of the marine world. Found mostly around rocky outcrops, these night predators stalk their prey keeping a watchful eye out for something tasty to pass by. At first the octopus can appear to quite dull in colour. Yet they change colour fast and have a greater variety of colours than a chameleon.
Facts about Octopus/wheke
Close up of octopus, Paterson Inlet,
Stewart Island
The octopus lives on average for only a year and is considered one of the most advanced and complex species of the mollusc family. Their sac like body disguises a hard beak, enclosed in a mantle, that they use to bite its prey. Octopuses sometimes eat mussels and other bivalves. They can get through the shells by either, pulling them apart with their strong arms or by boring a hole in the shell with their radula. The radula is like a tongue except that it has a row of “teeth” on it. The octopus has eight arms and unlike its cousin the squid, does not have any tentacles.
This animal has quite a lot of muscle in their arms and mantle. The biggest difference between an octopus's muscles and ours is that they do not have bones to attach their muscles to. This allows them to work their arms into tight places and to be very adaptable. However, they don't have the leverage that we have with bones. When looking at an object, they are not able to sense how heavy it is. Instead they pass their suckers over the surface of an object, tasting through their suckers and deciding whether to take or reject the object.
Diet
Octopus maorum
Octopus live on a diet of fish, crustaceans and molluscs however their favourite food is crayfish. Octopus have excellent eyesight and will stalk their prey in much the same way as a cat will, hiding behind rocks and pouncing on unsuspecting prey. If their prey can move, an octopus will often swim above it and then spread its arms parachuting onto it. In this way the octopus uses its body like a net to catch its prey.
Female octopuses will not eat after they have laid their eggs – not even after the eggs have hatched. When they have laid their eggs, females will guard them and look after them by keeping them clean and scaring away predators. After the eggs have hatched the female will die.
Strange octopus facts
An octopus can regenerate a lost arm and it is quite common to find octopuses missing arms in nature. Octopuses have very advanced brains for invertebrates with two thirds of their nerves in their body and arms, not the brain! This gives the arms a lot of local control. It also allows the detached arm to continue to crawl, suckers to suck, and chromatophores to change colour - all of which makes an effective decoy.
Another unique feature of the octopus is that it has three hearts!! Each gill has its own heart to pump blood through. Blood picks up oxygen in the gills, but after going through all those tiny little capillaries, it loses its pressure. The third heart then pumps the oxygenated blood to the tissues all over the body. We mammals do this with one heart. One side pumps blood to our lungs where it picks up oxygen, it then returns to the other side which pumps blood out to the tissues.
If an octopus is stressed it usually changes colour to either white or red. When an octopus is threatened and changing colour has not deterred their predator, they will use a cloud of ink to escape. This ink is contained in an ink sac that is connected to the end of the digestive system.Threats to octopus/wheke
Octopus maorum on the beach,
Hawke's Bay
Powelliphanta snails
Hidden away in New Zealand’s forests and grasslands is a bewildering array of native land snails, which range from the microscopic to the massive.
Among these are at least 21 species and 51 sub-species of Powelliphanta snails – which represent some of the most distinctive invertebrates in New Zealand.
Facts about Powelliphanta snails
Giant land snail
Powelliphanta snails are not your common garden snail! In fact, they are totally unlike garden snails, which are a European import and an unwanted garden pest.
Powelliphanta are giants of the snail world. They can reach up to 90mm across, or the size of a man’s fist.
They are also beautiful. Their oversize shells come in an array of colours and patterns, ranging from hues of red and brown to yellow and black.
And Powelliphanta snails are most unlikely to be found in your garden. Most favour living in the forest, and particularly like to eat earthworms, sucking them up through their mouth just like we eat spaghetti!
In fact, these meat-eating giants of the forest floor are true biological oddities. They 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. A total of 40 species or subspecies are ranked as being of national conservation concern.
Facts about Powelliphanta
- Powelliphanta snails are carnivores. Their favourite prey is earthworms, but they are also known to eat slugs.
- The largest species is Powelliphanta superba prouseorum, found in Kahurangi National Park and measuring about 90mm across. These are the Sumo wrestlers of the snail world, weighing in at 90g, or the equivalent of a female tui!
- The genus was named after Dr A.W.B. Powell, a former scientist at Auckland Museum who studied the snails during the 1930s and 1940s.
- Powelliphanta snails used to be known as Paryphanta snails, until the 1970s. Now, Paryphanta refers only to kauri snails, which live north of Auckland.
- Powelliphanta snails are hermaphrodites, meaning they possess both male and female reproductive organs and therefore can mate with any other adult Powelliphanta.
- Powelliphanta snails lay about 5-10 large eggs a year. Each egg is up to 12-14mm long, pearly pink and hard-shelled - just like a small bird’s egg!
- Powelliphanta are nocturnal. For the most part, they live buried in leaf mould or under logs, only coming out at night to forage and to mate.
- It is estimated that Powelliphanta snails can live up to 20 years. In snail terms, that is an incredibly long life span!
- Because Powelliphanta snails are prone to dehydration, they cannot survive in dry conditions. For this reason, they are more common in moist high-altitude forest than in drier forests at lower altitudes.
Where to find Powelliphanta
Snail distribution map
The stronghold for Powelliphanta snails is in North West Nelson and north Westland, where most of the species occur.
They are also found in the Marlborough Sounds and Mt Richmond Forest Park, as far south as Fiordland and Southland and, across Cook Strait, on parts of the Kapiti Coast and into the central North Island.
Different Powelliphanta species can be found from sea level, where they live in rich temperate rainforest, to above the bushline. Most of the alpine species have to contend with prolonged snowfalls and bitterly cold winters. The most likely sign of their presence will be empty snail shells on the forest floor.
Visitors will be unlikely to spot a live snail, except at night or occasionally on rainy days. They are most likely to be active on warm, moist nights after a long dry spell, when they will be out foraging for food.
Weta
Weta are incredible looking creatures. They range in size, but with their big bodies, spiny legs, and curved tusks, they are one of New Zealand's most recognisable creepy-crawlies.
Facts about weta
Weta have become icons for invertebrate conservation in New Zealand because many species are threatened or endangered. There are more than 70 species of weta in New Zealand, 16 of which are at risk.
Cave weta
There are five broad groups of weta:
- Tree weta
- Ground weta
- Cave weta
- Giant weta
- Tusked weta
Diet: Weta are mainly herbivorous in the wild, but are also known to eat insects.
Habitat: They are nocturnal and live in a variety of habitats including grassland, shrub land, forests, and caves. They excavate holes under stones, rotting logs, or in trees, or occupy pre-formed burrows.
Many different species
The wetapunga of Little Barrier is the biggest, and the Nelson alpine weta the smallest, at 7 grams. There are tree weta, ground weta, cave weta, and three species of the spectacular looking tusked weta. These males have two tusks which they use to butt other males, or rasp together to warn off competitors.
Species of weta continue to be discovered. One of the three tusked species, the carnivorous "Jaws", was found by lizard expert Tony Whittaker on Middle Mercury Island off the Coromandel Coast 29 years ago; another of them in the Raukumara Ranges on the East Coast of the North Island as recently as 1995.
Many of the giant species now only survive on protected land and many are endangered. The Mahoenui giant weta, long considered extinct on the mainland, was rediscovered in a patch of King Country gorse in 1962. Department of Conservation staff have established a new population of these on Mahurangi Island, off the Coromandel coast. Two hundred have been transferred there and after four years they are showing signs of breeding.
The challenge of classifying weta
One feature of weta conservation is the lack of basic information on their distribution, abundance, and ecology. Furthermore, there can be a great deal of variation within individual species, despite the fact there is little genetic difference between them.
Therefore, the classification and conservation of weta is an evolving process.
A Department of Conservation Recovery Plan is currently in action. It exists as a guide that can be modified as new information and conservation priorities emerge.
Population and range
Little is known about the past distribution of weta.
Several species that were once found on mainland New Zealand are now only found on offshore islands. Very little is known about these offshore island populations.
Threats to weta
Tusked weta
The decline of most weta is due to three major causes:
- Predation
- Weta have evolved alongside native predators such as birds, reptiles, and bats. The introduction of predators such as rats, mustelids, cats, and hedgehogs has resulted in a sharp increase in the rate of predation.
- Habitat destruction
- Caused by human impacts
- Browsers
- Modification of weta habitat caused by browsers.
Potential for recovery
The potential for recovery is quite high for a number of reasons:
- Invertebrates respond well to management because they have a high rate of productivity.
- Many weta adapt well to modified habitat.
- Invertebrates also require smaller areas to survive than vertebrates, and can survive in tiny fragments of original habitat.
- Weta also thrive in captive breeding programmes. This is useful, because it means that research can take place that is difficult to obtain in the field.
Past conservation efforts
Management and research to date has centred on various types of giant weta, as well as several types of tusked weta, and tree weta.
Tokoriro
Cave weta are found all over NZ, and might appear a bit terrifying. It turns out these wild-looking weta are harmless, deaf and probably more scared of you than you are of them.
Mahoenui
The giant weta has been around for 190 million years, making it one of New Zealand’s oldest creatures.
Freshwater fish
New Zealand has 35 native fish species, yet most of us would be hard pressed to list more than a couple (and no, trout are NOT native!). People are astounded to learn that ‘whitebait’ are the juveniles of five native species, including some that are threatened.Facts about native fish
Did you know that half of our native fish species spend time at sea? In this section you'll learn more about some of New Zealand's 35 native fish species.
Banded kokopu
Banded kokopu
Adult banded kokopu have numerous pale stripes across the body and can grow up to 26 cm long. They are good climbers and make their way upstream until they find small forest streams with plenty of cover and shade.
Bluegill bully
Bluegill bully
The bluefill bully usually grows to about 5 cm long. It has an ‘upturned’ mouth which it uses to pick its food (aquatic insects) from beneath rocks. This fish prefers swiftly flowing gravelly streams, just like the torrentfish.
Common bully
Common bully
Even though they are well camouflaged against sand and rocks, common bully are often seen darting in the shallows during the day. The male guards the nest and when the eggs hatch, the larvae go to sea to return to freshwater after a few months. However some populations become landlocked and complete their life cycle without the sea phase.
Common smelt
Common smelt
The small shimmering silver fish occur in large shoals in estuaries and lowland rivers. They spend most of their lives at sea. Some return to freshwater as juveniles in spring but most return as adults in summer when they are about 10 cm long. They can also be found in some lakes.
Dwarf galaxias
Dwarft galaxias
Dwarf galaxias prefer stable gravelly upland streams and live in the spaces between rocks and stones of the streambed. They usually grow to about 5 cm. They are considered threatened.
Eel
There are two main types of eel – the Shortfin and the Longfin. There are fewer eels today because of the loss of wetlands and commercial fishing. Eels migrate up streams as elvers to find suitable adult habitat. After many years (15-30 years for shortfins, 25 years for longfins, and sometimes up to 80 years) they migrate to the Pacific Ocean to breed and die. Eels are secretive, mainly nocturnal and prefer habitats with plenty of cover.
Shortfin eels
For at least 65 million years, long-finned eels (Anquilla dieffenbachii) have been swimming up and down New Zealand’s waterways.The long-finned eel is one of the largest freshwater eels in the world and it is found only in the rivers and lakes of Aotearoa, New Zealand. Longfin eels are threatened fish.
About the Long-Finned Eel
Habitat
Long-finned eels can be found throughout New Zealand. They live mainly in rivers and inland lakes but can be found in almost all types of waters, usually well inland from the coast.
They are legendary climbers and have made their way well inland in most river systems, even those with natural barriers. Elvers (young eels) swimming up river will climb waterfalls and even dams by leaving the water and wriggling over damp areas. It is not unheard of for an eel to climb a waterfall of up to 20 metres.
Size
When eels begin life, they are a tiny one millimetre in length. During their life, they can grow up to two metres long.
Compared with many other fish, eels are slow growing - a long-fin may grow only between 15-25mm a year. They can also live for many years. Large long-fins have been estimated to be at least 60 years old.
The biggest eels are usually old females that have been slow to reach sexual maturity and, for reasons that are not yet understood, have not migrated to sea to breed.
The biggest long-finned eels reported have weighed as much as 40 kg. Pictures of fishers and huge eels used to appear regularly in local newspapers. But today, you’ll seldom find an eel heavier than 10 kg. Commercial fishing has meant that a big proportion of our very large eels have now disappeared.
Appearance
In shape, eels are elongate, slender-bodied fishes, almost tubular. When they are small, they have relatively smooth heads but as they grow the head becomes bulbous, with a prominent muscular dome behind the eyes.
They change shape again when they get ready to migrate to their breeding grounds. The head becomes much more slender and tapered, almost bullet-like and the eyes enlarge to up to twice their normal size.
Like all fish, eels have scales and fins. The long-finned eel is so named because its top (dorsal) fin is longer than its bottom fin.
While they have the appearance of being scaleless, tiny scales are embedded deeply within their thick, leathery skin. The eel’s skin is very sensitive to touch. This helps it to "see" in its watery environment.
In colour, long fins are usually dark brown to grey black. Very occasionally, long-finned eels found in the wild are partially or even wholly bright yellow in colour.
Food
Eels eat "live" food. Small long-finned eels living amongst the river gravels will feed on insect larvae, worms and water snails. When they get bigger, they begin to feed on fish. They will also eat fresh-water crayfish and even small birds like ducklings.
During the day, eels are secretive, hiding under logs and boulders or under riverbanks. Occasionally, they may be seen out hunting for food but most of their hunting takes place at night.
Eels hunt by smell rather than sight. Long-finned eels have a well-developed sense of smell. They have tube nostrils that protrude from the front of their head, above their upper lip.
They also have a very large mouth with rows of small, sharp, white teeth. The top teeth form an arrow shape on the roof of the eel’s mouth.
Breeding
Long-finned eels breed only once, at the end of their life. When they are ready to breed, they leave New Zealand and swim five thousand kilometres up into the tropical Pacific to spawn, probably in deep ocean trenches somewhere near Tonga.
When they reach their destination, the females lay millions of eggs that are fertilised by the male. The larvae are called leptocephalus and look nothing like an eel –they are transparent, flat, and leaf-shaped. The larvae reach New Zealand by drifting on ocean currents.
Before entering fresh water, the leptocephalus change into a more familiar eel shape, although they remain transparent for up to a week after leaving the sea. These tiny "glass" eels enter fresh water between July and November each year, often in very large numbers.
Eels take many years to grow and it could be decades before an individual is ready to undertake the long migration back to the tropics to breed. The average age at which a long-finned eel migrates is 23 years for a male and 34 for a female. The adults never return as they die after spawning.
Threats
While long-finned eels are still relatively common, fishing has had a significant impact on the species. Europeans showed little interest in eels as a fishery until the 1960s when commercial catches rose steadily.
In 1975, eels were the most valuable fish export after rock lobsters. Five years later, they were the fifth most valuable finfish export. This big increase in fishing effort led to significant stock reductions in some areas, with a marked decline in the average size of the eels caught.
Habitat loss also affects eels. Changes caused by hydro development, drainage and irrigation schemes and river diversions affect eels by reducing their habitat and the water available for aquatic life. Culverts and dams can also impact on eels by preventing their migration.
Eel habitat is also impacted by pollution. Sewage and effluent from meat works and pulp and paper plants discharged into rivers can remove large quantities of oxygen from the water. The result of this oxygen depletion is that the fish will either die or move away.
Eels on the Move
Hydro dams stop eels moving freely up and done some rivers. To get around this problem eel passes have been built across some dams to help the eels complete their journey. Young eels may also be moved across the dams by hand.
Activities
- Find out about the eel fishery in New Zealand and the problems associated with fishing a slow-growing, long-lived species.
- On a map, trace the journey of the long-finned eel as it leaves New Zealand to breed. Work out how far it travels.
- Design a board game. You could call it "Eels and Ladders". Players move around the board, winning points for actions that protect the long-finned eel and loosing points for actions that harm it. For example, one square could read "You go to the Environment Court to stop a company discharging toxic effluent into the river. Move ahead 5 squares." Another square could read "You drain a wetland, reducing the habitat for eels. Go back 6 squares".
- Discuss attitudes and feelings about eels. What do students think of when they hear the word eel? What does an eel feel like? Get students to make up poems about eels by putting up on a board all the words they associate with eels. .
- Hold a class debate on a proposed drainage scheme which would reduce the level of water in a river where eels live.
- Read Watercress Tuna and the Children of Champion Street by Patricia Grace. Have students write and illustrate their own stories about an eel.
Giant bully
Giant bully
This dark-coloured fish prefers lowland waterways especially estuaries and is almost always found beneath cover, only to emerge at night to feed. It can grow over 15 cm long. It is presumed that giant bullies have a marine phase in their life cycle, but this is not known for sure.
Giant kokopu
Giant kokopu
The giant kokopu is a threatened native fish. It is secretive and loves having plenty of cover to hide under, preferring gently flowing overgrown streams, swampy lagoons and lake edges.
Inanga
Inanga
Those that escape the whitebait net grow into silvery, slender
adults (about 9 cm long). They spawn in streamside vegetation, even
rank exotic grasses are suitable. Inanga are found in lowland
slow-moving streams. They do not climb waterfalls or swim up steep
gradients. Like other members of the whitebait family they have gold
flecky skin but no scales.
Koaro
Koaro
Koaro are spectacular climbers and use their flattened fins to scramble up waterfalls in order to reach shady bouldery forest streams. Koaro have a distinctive greenish-brown patterning and commonly grow to a length of an adult handspan (16-18cm) although some have been found up to 30cm long.
Lamprey
Lamprey
Lamprey juveniles (ammocoetes) live in burrows in silty river edges and migrate out to sea after 4-5 years. Whilst at sea, the lamprey are parasites on marine life until, after another 4-5 years they migrate back up streams to breed and die. Maori consider lamprey or piharau to be a delicacy. They are threatened fish.
Mudfish
Mudfish/kowaro are regarded as a taonga (treasured) species to iwi. They look like cigar-shaped, stocky eels with slippery skin covered with dark greenish-brown speckling. Mudfish live in weedy drains, wetlands and pools in swamp forest. They survive when the water dries up by hiding away underneath logs or debris and emerge when rain falls. They grow to about 11cm.
Brown mudfish
There are five species of mudfish all of which are threatened:
- Northland mudfish - found around Kerikeri and Ngawha
- Black mudfish - found in Northland and Waikato
- Brown mudfish - mainly found in southern North Island and the West Coast of the South Island
- Canterbury mudfish - found in Canterbury as far south as the Waitaki catchment
- Chatham Island mudfish - a recently discovered mudfish species, found in two lakes on Chatham Island.
Once widespread in swamps and wetlands, mudfish are now found in only a few sites – mostly on private land. DOC is working with landowners to protect these key remaining habitats.
A fish out of water?
Mudfish can do something most other fish can't – they can survive without water for about two months! All they need is vegetative cover to keep themselves moist. Then, when summer is over and water returns to the wetland, they can eat, swim and breed. This adaptation means that mudfish can live in places other fish can't.
Other bullies
Upland bully
The upland bully and cran’s bully are non-migratory bullies. They are difficult to tell apart in the field and both lack the head pores that other bullies have. They can grow to about 8 cm long and can be found in a variety of habitats.
Just to add to the confusion there are some marine fish that like to
venture into freshwater from time to time. These include the black
flounder which can be found a long way inland, the yelloweye and grey
mullet which cannot live permanently in freshwater but penetrate large
northern rivers, the stargazer which prefers salty water to fresh, the
cockabully which is found in estuaries, the yellowbelly flounder which
can be confused with the black flounder and the kahawai which despite
being a marine fish can move several kilometres upstream.
Redfin bully
Redfin bully
Redfins are distinguished from other bullies by having diagonal cheek stripes and grow up to 12 cm long. Like other bully species, the male guards the nest before the larvae get washed out to sea, and migrate back to freshwater as small juveniles.
Shortjawed kokopu
Shortjawed kokopu
The shortjawed kokopu is the kiwi of the water world – secretive, nocturnal and threatened. It climbs upstreams in search of shady places with lots of cover such as logs, large boulders and undercut banks.
Torrentfish
Torrentfish
This aptly named fish is found amongst swift tumbling riffles and is
related to the blue cod. Like the whitebait family, the larvae get
washed out to sea and the juveniles return to freshwater in spring and
summer. Torrentfish are relatively common with most adults growing to
about 10 cm.
Whitebaiting
The whitebait fishing season for most of New Zealand opens on 15 August and runs until November 30.
On the West Coast the whitebait season runs from 1 September until 14 November.
