basommatophorans

Basommatophorans are an infraorder of air-breathing freshwater and brackish snails. They belong to the order Pulmonata, characterized by the presence of lungs. A defining feature of basommatophorans is the position of their eyes, which are located at the base of their tentacles, unlike the stylommatophorans where eyes are at the tips of the tentacles. These snails typically possess a coiled shell, though shell coiling can vary in extent among species. Their habitat is primarily aquatic, found in a wide range of freshwater environments such as ponds, lakes, rivers, and marshes. Some species can also tolerate brackish water conditions. Basommatophorans are important components of aquatic ecosystems, serving as food sources for various animals and playing roles in nutrient cycling. They are often hermaphroditic, possessing both male and female reproductive organs. Reproduction can occur through self-fertilization or cross-fertilization. Examples of well-known basommatophoran families include Lymnaeidae, Planorbidae, and Physidae. Some species within this group are of medical or veterinary importance, acting as intermediate hosts for parasitic trematodes that can affect humans and livestock.