Biomphalaria tenagophila is a species of air-breathing freshwater snail, an aquatic pulmonate gastropod mollusk in the family Planorbidae, the ram's horn snails. This species is medically important pest, because of transferring the disease intestinal schistosomiasis. (Intestinal schistosomiasis is the most widespread of all types of schistosomiasis). The parasite Schistosoma mansoni, which Biomphalaria snails carry, infects about 83.31 million people worldwide. The shell of this species, like all planorbids is sinistral in coiling, but is carried upside down and thus appears to be dextral.