Ryan Photographic - Tateidae - Freshwater and mud snails
The family Tateidae is a family of tiny, freshwater, and estuarine snails. They possess an operculum which gives them an extraordinary ablity to resist both dessication and digestion (see discussion below).
There are 9 species in the family distributed amongst six genera.
Potamopyrgus antipodarum has become invasive in parts of North America and Europe. Originally from New Zealand and probably spread via ballast water to Europe (and by fishermen's waders to North America) it has spread widely. Part of the reason for its spread is its ability to withstand digestion. When I was doing my doctorate on the New Zealand shortfinned eel, I fed eels with the mud snail in an attempt to work out the calorific value of the snails. The experiment involved force feeding a known weight of snails to a batch of ten eels and then collecting the fecal material that was produced. I was somewhat nonplussed to find that a high proportion of the snails were cruising around the experimental chamber having passed successfully (and safely) through the eel gut. This helps explain the speed with which the species has spread. Predators such as trout and eels ingest the snail and defecate, sometimes hundreds of metres upstream from the ingestion point. It's kind of like us catching a high speed train - but with a very high death rate!
Potamopyrgus antipodarum, New Zealand mud snail
Potamopyrgus antipodarum, New Zealand mud snail, Taumutu, New Zealand IMG_9159
Potamopyrgus antipodarum, New Zealand mud snail, Taumutu, New Zealand IMG_9164