Physa spp

We keyed the species below out as either Pyhsa fontinalis (Common Bladder Snail) or Physella acuta (American Bladder Snail). We did manage to get some footage down the microscope of an adult and what may be a juvenile of the same species next to it…

One of the interesting points to note about physa species is they are very tolerant of pollution and enrichment and as such cannot be seen to indicate in anyway good water quality.

An odd thing about Physa species is that their shells are ‘Sinistral’, which literally means ‘too the left’ (or ‘on the left-hand side’). Most gastropods have shells which spirals are in a clockwise manner, the principle being if you hold a shell with the spire pointing upwards and the shell opening facing you, then the opening will normally be on the right-hand side. As can be seen from the image below, for Physa specimens the opposite is true, the opening is on the left…

What are they doing in the Garden: These little guys are found in the fishpond, the middle wildlife pond and the wetland open water area. They feed on algae and detritus and are a long term and permanent resident in the Garden. It is unclear what predates this species, although it is safe to assume our amphibian residents are high up on the list.