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PHOTO CREDIT: Rohan Wells, NIWA NIWA SUMMER SERIES: KOURA Exploring NZ���s fabulous FRESHWATER FAUNA Koura glow-in-the-dark limpet, a ���erce-looking ���toe-biter��� more substantial variety are your thing, you can���t go past the (which isn���t ���erce at all and would scarper at ���rst sniff centipede-like toe-biter Archichauliodes diversus, one of our of your toe), and a may���y that lacks a functioning mouth largest aquatic insects. ���It derives its common name from its rather threatening(and, not-surprisingly, lives as an adult for only a few days), are just some of the weird and wonderful critters to be found in looking pincers, but in fact it���s completely harmless to us,��� Dr Storey says.���It has ���nger-like gills running down its back, which New Zealand���s 425,000 kilometres of streams and rivers. Our freshwater fauna are wonderfully diverse and, according make it look like a centipede, but in fact it has only six legs, like to NIWA Freshwater Ecologist Dr Richard Storey, there���s any other insect. At ���ve centimetres long, it is one of our more impressive stream-dwellers. You could be lucky enough to ���nd nothing among them that we need to be afraid of. ���You can ���nd a suitable stream, wade in, turn over rocks one by turning over rocks in the stream.��� That���s also the habitat of the may���y ��� a small, three-tailed and explore amongst the plants and plant debris, safe in the knowledge that none of our stream-dwelling critters will hurt insect that has a ���attened body shape and uses its gills like an aerofoil to stay stuck to submerged rocks, where it feeds on algae. you. It���s a fabulous way to spend a summer���s day.��� The poor adult Deleatidium spp., our most common may���y, Dr Storey says that New Zealand has several hundred freshwater invertebrate species, and 13 genera (a higher doesn���t enjoy much luxury in life. ���After spending a year as classi���cation level than species), form a common group that can larvae, it hatches without a functioning mouth or any other be found right across the country. Here���s a quick look at some means of ingesting food,��� explains Dr Storey. ���Its sole purpose as an adult is to mate and lay eggs, a process that takes one to three of the more quirky among them: The koura, or freshwater cray���sh, is probably our best- days ��� and then it dies! That���s life pared back to the bare basics. ���You may remember a Vodafone TV advertisement from a known stream-dwelling invertebrate. A koura grows to between ���ve and ten centimetres long and can be quite few years ago that used a cartoon may���y to communicate the dif���cult to spot as it hides out among logs and other plant company���s ���make the most of now��� slogan ��� very appropriate!��� The caddis���y is another commonly found freshwater matter on the stream edges. ���If you investigate underneath rocks, leaf litter and tree fern resident. Two types are seen in New Zealand. One lives in a fronds, you���ll probably ���nd one,��� says Dr Storey. ���And if you slightly curved, stick, or stone-like case. The stick-caddis fools have the chance, try exploring by torchlight at night. That���s would-be predators into thinking it is a twig. The stony-caddis when koura are most active, and their eyes shine bright blue uses its heavier case as an anchor so it can live and feed in faster���owing water. The other type is free-living, making its home in when the light catches them.��� That glow-in-the-dark quality is shared by the tiny freshwater leaves and other loose material at the base of rocks. ���Some free-living caddis���ies spend their time building a limpet (Latia neritoides), which activates an in-built warning system when disturbed. ���It excretes a luminous mucus, designed net-like structure something like a spider���s web, which catches to put off predators, that glows green in the dark,��� says Dr Storey. ���oating fragments of leaf and other morsels it can feed on,��� Dr The limpet grows to a mere 12 millimetres long and is Storey explains.���It periodically scuttles out to feed and clear any vulnerable to swift currents, so prefers to spend its time feeding unwanted debris, then returns to the safety of its ���house���.��� The caddis���y is closely related to the caterpillar. ���The adult on bacteria and other ���bio���lm��� living on rocks in warm, slow���owing water. For that reason, it is more common in the north. looks like a moth, because it almost is.��� Dr Storey has been investigating these and other ���And while we���re on the subject of creatures that glow, let���s not forget the beautiful glow-worm. They���re not actually fascinating freshwater creatures since the age of nine, when worms at all, but larvae of the rather unfortunately named his interest in freshwater ecology sparked. He has now spent fungus gnat (Arachnocampa luminosa). They���re quite common, close to 20 years, the last eight with NIWA, getting to know so if you���re out exploring at night you might be lucky enough the myriad invertebrates that call New Zealand���s streams and rivers, home. to spot some on banks overhanging streams. The water keeps ���There���s so much still to be them cool and moist.��� fly discovered,��� he says. ���That���s the The glow-worm���s blue-green light is produced by ddis Ca exciting thing. I encourage chemical reactions in a kidney-like organ common young and old to get out to all insects. The glow-worm has the unique there and see what they ability to produce light, which is used to can ���nd. It really is an attract food and a mate. amazing world.��� If creepy-crawlies of the MARCH/APRIL 2013 ��� PHOTO CREDIT: Brian Smith, NIWA A NZ AQUACULTURE ��� 9