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How to find a Limpet


Sarah Lacey

Today I received my wish to go in a helicopter! I successfully followed all the instructions to safely enter and exit and it was just as awesome as I thought it was going to be. It is a completely different sensation than going in a plane, that made me much less motion sick. You also fly closer to the ground so I observed many different herds of cattle along the way. Being up the sky made me assess how dry the landscape was and how the density of vegetation increased as we came closer to a river. I was with the Curators of Fish (Glen Moore & Michael Hammer) and a mollusc expert (Lisa Kirkendale) so we were looking for good waterbodies to sample.

The first site was an offshoot of the Gibb River with many rocky banks and small waterfalls. Here is where I started my search for a mollusc. At first, I was looking for shells, things I was familiar with around 3-4 centimeters big. However, that is not what I was meant to be looking for. The organisms that were present at the site were less than a centimeter big, you had to look under rocks and very closely at the shoreline, sometimes using your fingers to feel for bumps under ledges. This allowed for a few surprises, including frogs, spiders and lizards that appeared under rocks I lifted. We did find a few samples under rocks in a shallow pool at this site. We also swam in the river to look at the bank for mussels. Instead, we found turtles, a long-neck and a red-face turtle species.

I also followed Glenn and Michael to see how they did their sampling. They were electrofishing. A device is placed in the water which emits an electric shock, this stuns the fish nearby and they float to the surface. Interesting fish are collected in a net, whilst the others are left to recover and swim away. I couldn’t follow them far as the river bank became impassable – and I couldn’t enter the water without protection from the electric field.

When leaving this site, the helicopter had to fly through the gorge leaning forward – this was excellent fun! At the next site, the helicopter landed on the edge of a waterfall… spectacular!

At this site, named Donkey Creek, I continued my search for molluscs. Now knowing the size of the things I was looking for I began looking in pools and turning over rocks and leaf detritus. I found an interesting “thing” about 2mm big attached to a leaf. This “thing” made Lisa’s day. We collected a population of these organisms and looked at them under the microscope in the lab. The organism I had found had only ever been described once in Australia. They are a freshwater limpet called Stimulator consetti. This was a significant discovery because the last description of this was in 1944 with limited detail. Now that a new population has been discovered and live samples taken, scientists at the WA Museum can describe and observe this species in significantly more detail.