The Banff Springs snail was first identified in 1926 in the nine sulphurous hot springs of Sulphur Mountain in Banff National Park, Alberta, Canada. It has been found nowhere else. It is very unusual because it is adapted to life in thermal springs where the water is low in oxygen and high in hydrogen sulfide, an environment too harsh for most animals to survive in. Since its discovery, its range has shrunk to just five of the nine hot springs.
The reduction in Banff Spring snail population and range is likely due to human use of the hot springs, although fluctuating water temperature is also a factor. In April 1997 it became the first living mollusc to be placed on Canada’s national list of species at risk. In 2000 it was classified as endangered by COSEWIC and the Canadian Species at Risk Act listed it in the List of Wildlife Species at Risk as being endangered in Canada.
During times when the numbers are critically low, the snail is most vulnerable to human disturbances or natural disasters (like the spring temporarily drying up). It is estimated that the population varies between 1,500 and 15,000 snails. At its lowest points, the entire population of snails can fit in an ice cream cone, and at its highest, in a one litre milk carton.
Although the largest snails are about the size of a kernel of corn, the majority are about half that size. It is easiest to spot them when they cling to algae, bacteria, sticks or rocks at the water’s surface, where they must go to breathe. The snails have dark eyes and a shell that spirals to the left. (Most snails have shells that spiral to the right ).