Invertebrates 101 Chapter 6
The Mollusks - Freshwater Snails
The Freshwater Snails are a remarkably varied and extensive group found throughout the world. Although found in almost every habitat, at least 30 different lineages of these Gastropods have evolved independently to colonize fresh water environments. As a group they have a multitude of life strategies. Some have gills and live completely underwater, others have lungs and need to surface periodically, some lay eggs, others are live-bearing, most have shells but some, like slugs, are shell-less. There are eight species of snails in North America, all of which share a few basic characteristics.
By Zachi Evenor [CC-BY-2.0], via Wikimedia Commons
Freshwater Snails typically consume both decaying and live plant matter. This makes them very useful scavengers, both in the pond and in the aquarium, where they continually clean up the algae and plant debris that accumulates.
Unfortunately, certain species’ tastes for living plants make Freshwater Snails major pests as well. People who really care about their prized aquatic plantings are less than thrilled with snails after they’ve destroyed their favorite specimens.
One issue that has been reported by pond owners is a consequence of mass die-offs of snails, when their empty shells clog filters and pump intake systems as they drift through the water. A good quality mechanical filtration system helps to control snail populations by keeping plant debris to a minimum.
“Escargots” are the preferred food of a number of predators that also help to keep them in check, including fish, frogs, toads, crayfish, snakes, turtles, birds and mammals like raccoons, even dogs and cats (not to mention the occasional French gourmand).
Speaking of escargots, one issue that could potentially impact the pond owner is the fact that Freshwater Snails are hosts in the lifecycles of a variety of human and animal parasites, particularly "flukes" but including some nasty unpronounceables like “Schistosomiasis”. As you would expect, you’ll want to avoid eating your snails without cooking them properly and of course, washing your hands after fondling them is strongly advised.
The Freshwater Snails are a remarkably varied and extensive group found throughout the world. Although found in almost every habitat, at least 30 different lineages of these Gastropods have evolved independently to colonize fresh water environments. As a group they have a multitude of life strategies. Some have gills and live completely underwater, others have lungs and need to surface periodically, some lay eggs, others are live-bearing, most have shells but some, like slugs, are shell-less. There are eight species of snails in North America, all of which share a few basic characteristics.
By Zachi Evenor [CC-BY-2.0], via Wikimedia Commons
Freshwater Snails typically consume both decaying and live plant matter. This makes them very useful scavengers, both in the pond and in the aquarium, where they continually clean up the algae and plant debris that accumulates.
Unfortunately, certain species’ tastes for living plants make Freshwater Snails major pests as well. People who really care about their prized aquatic plantings are less than thrilled with snails after they’ve destroyed their favorite specimens.
One issue that has been reported by pond owners is a consequence of mass die-offs of snails, when their empty shells clog filters and pump intake systems as they drift through the water. A good quality mechanical filtration system helps to control snail populations by keeping plant debris to a minimum.
“Escargots” are the preferred food of a number of predators that also help to keep them in check, including fish, frogs, toads, crayfish, snakes, turtles, birds and mammals like raccoons, even dogs and cats (not to mention the occasional French gourmand).
Speaking of escargots, one issue that could potentially impact the pond owner is the fact that Freshwater Snails are hosts in the lifecycles of a variety of human and animal parasites, particularly "flukes" but including some nasty unpronounceables like “Schistosomiasis”. As you would expect, you’ll want to avoid eating your snails without cooking them properly and of course, washing your hands after fondling them is strongly advised.
