Spherium refers to a genus of very small freshwater clams belonging to the family Sphaeriidae. These clams are commonly known as pea clams or pill clams due to their small size and rounded shape. They are found in various freshwater habitats, including lakes, ponds, streams, and rivers, worldwide.
Spherium clams are hermaphroditic, meaning each individual possesses both male and female reproductive organs. They are capable of self-fertilization, although cross-fertilization is also possible. They are ovoviviparous, retaining fertilized eggs within their brood pouches until they hatch into juvenile clams, which are then released.
These clams are filter feeders, extracting organic matter and algae from the water column. They play a role in aquatic ecosystems by contributing to nutrient cycling and serving as a food source for various invertebrates and fish.
Identification of Spherium species can be challenging due to their small size and morphological similarities. Features used for identification include shell shape, hinge teeth arrangement, and the presence or absence of a siphonal opening.
Spherium clams are often used as bioindicators of water quality. Their presence or absence, as well as their abundance and condition, can provide insights into the health and pollution levels of aquatic environments. Some species are more tolerant of pollution than others, making them useful for assessing the impact of human activities on freshwater ecosystems.