A couple of weeks ago I got the opportunity to go and have a wander around a stream near a friends house. After poking at various insects and other creepy crawlies, it occurred to me to have a look in the water and see if I could find anything a bit different than the usual insects I find. It just so happens that I found this fellow (click images for full sized picture..theoretically anyway):
This fellow is a freshwater crayfish, one of two species in New Zealand Paranephrops zealandicus, or more commonly known as the Southern Koura. The other species, rather boringly enough, is simply called the Northern Koura (Paranephrops planifrons) and is rather similar to the Southern Koura, but is often of a smaller size. Moving some rocks around revealed something moving about in the water and closer inspection revealed several Koura wandering about. Catching them was a little tricky, as they are extremely fast and stirring up sediments makes life much harder, but in the end I succeeded (for SCIENCE!). Once ready for his photoshoot this guy* was rather happy for the most part to sit up for the camera and have his photograph taken, but there was one rather dramatc incident towards the late afternoon.
As you can see, naturalism can be a dangerous hobby, as the little crayfish grabbed my thumb and squeezed with all his crayfishy might. I can assure you, that really did hurt and it actually took me a while to get him off my thumb. Other than that, numerous pictures were taken and good times were had by all.
Once finished with his exciting photoshoot, he was released back into the stream to do whatever it is he spends time doing, most likely hiding under rocks during the day to surface at night to feed on small critters and algae. You’ll notice growths on the animals head and claws in all of the photos, which I figure is either the direct result of their feeding habits on algae (just getting some stuck on) or growths that provide some degree of camouflage. Unfortunately though, Koura are becoming harder to find in New Zealand as introduced aquatic predators (namely trout) and pollution of their natural habitat takes its toll. Unlike many species of freshwater crayfish, New Zealand Koura have no marine phase in their lifecycle, so once they go extinct they are unfortunately unable to re-colonise an area they have been removed from.
*I will immediately concede I’m no expert on determining the sex of freshwater crayfish. He didn’t have any eggs, which would be the obvious giveaway.