#conchostraca

One of the mornings for the Great Southern BioBlitz was spent out on Dingo Rock, one of the granite inselbergs in the area. It took me quite a long time to find the gnamma hole I'd seen on a previous trip, but once I did I mostly neglected the rest of the rock, since it was crawling with fascinating species. Gnamma holes are quite important to the local wildlife (and previously, the people), since they're the only freshwater available in the entire district, once the hot weather starts. Groundwater around the Wongan Hills is highly saline, which has become a huge problem after the massive landclearing for wheat farming.

Anyway - one of the species in the pool were these almost grape-sized Clam Shrimp, frantically mating before the shallow parts of the pool dried out completely. The eggs will survived, encysted, in the dry mud at the bottom of the pond until the winter rains come around again. In some species the eggs can wait seven years.

Clam Shrimp have been around since at least the Devonian. Most genera swim using their antennae, but Lynceus can open their bivalved carapace enough to swim with the legs as well.