This cache has been placed to raise awareness of our native freshwater fish/Invertabrate species. Over time I will add more caches in the Wanganui Region with the same theme. Native fish are something I have great interest in, and was one of my hobbies before I was engulfed in this Geocaching thing ;-)
Paranephrops is a genus of freshwater crayfish species endemic to New Zealand. They are known as koura in New Zealand, derived from the Māori language. Koura occupy freshwater streams, lakes, rivers and swamps.
Koura belong to the crab family – the Crustacea – so called because they have a hard shell like a crust, called an exoskeleton. This protects the koura from its enemies but it has a big drawback. It doesn’t expand as the koura grows. So when the koura grows and its shell gets too tight, it splits open. The koura squeezes out and makes a new shell. This is called moulting. Koura hide while they are moulting because they are soft and unprotected so it is a very dangerous time.
Koura at home
Koura live under rocks, roots or in holes in the bank. They come out at night to avoid being eaten by eels, shags and trout. They are scavengers, eating rotting plants, insects and worms. By eating and recycling leaves and dead things that fall into the water, they help keep streams clean. Their big pincers are useful for tearing up food, fighting other koura and scaring their enemies away. They will nip you too!
Escape artists
Koura walk about on their four pairs of walking legs. If they get a fright, they can flick their tails forward really fast and zoom backwards into hiding.
Koura can grow up to 30 cm long and live for 20 years – that’s pretty old! They can also change their appearance to match their surroundings – becoming green, brown, grey, black or patterned.
The Koura’s life cycle
Koura start life as eggs. The female koura lays up to 200 eggs and carries them under her tail for safety. After 3 or 4 months, the baby koura hatch. They look exactly like their parents but they are very, very tiny. They hang on their mother’s pincers until they are 4mm long.
Then they are on their own. They will moult again and again and get bigger and bigger. When they are four years old they will become adults.
Koura are in trouble
Their numbers are falling. They are now classed as ‘threatened species’
Why?
• They have lost their homes. They die where stream sides are cleared and the water is muddy with soil and cow poo.
• They are killed by pollution. Chemicals and rubbish in streams are the culprits.
Yes there are Koura in the stream below the cache. Infact there are koura in many streams in the Wanganui region, you just have to know where to look. Spotlight at night makes it easy to see them. Look for the glowing orange eyes.