Globular Peaclam, photo by Ian Gardiner
When we think of wildlife in BC, we tend to think of the larger photogenic species such as bears, elk, fish, and turtles. Or we think of the colourful, often alien-looking, species of tidal pools and other marine habitats. The sea stars, the nudibranchs, the sea urchins, the jelly fish. Oh, and sharks and whales. We don't always think about the really teeny species, 'invisible' species such as peaclams.
Peaclams are a group of freshwater bivalves that are found in lakes, ponds, rivers and streams throughout BC. They are characterized by their tiny size and presence in freshwater habitats and they are usually associated with freshwater vegetation. In BC, we have fourteen species of peaclams listed, including the Alpine Peaclam, the Pygmy Peaclam and the Globular Peaclam.
The Globular Peaclam, Cyclocalyx ventricosum (syn. (Pisidium ventricosum), is a tiny species of clam that is found throughout North America. In Canada, it is found from Newfoundland to British Columbia, "north to Ungava and the western Arctic coast" (BCCDC 2014). It is found in permanent (perennial) water bodies (lotic and lentic habitats) such as lakes, ponds, and rivers--it has never been found in ephemeral or temporary aquatic habitats (BCCDC 2014).
In their guide to freshwater molluscs of the Laurentian Great Lakes, Mackie et al. describe the Globular Peaclam as occurring on muddy and sandy substrates, but indicate that it shows preference for "soft sediments in quiet shallow waters" (Mackie et al. 1980). Ecologically, this species has been found to be present in greater numbers "in the upper sediment layers closer to sites of marl deposition" (IUCN 2014).
The BC Conservation Data Centre considers this species to be "relatively uncommon" in BC (BCCDC 2014). However, its tiny size means that, unless you are specifically looking for it, it is likely to be overlooked.
View the E-Fauna BC photo gallery for the Globular Peaclam here.
Visit the E-Fauna BC atlas page for this species here.
Mackie, Gerald L. David S. White, Thomas W. Zdeba. 1980. A guide to freshwater mollusks of the Laurentian Great Lakes, with special emphasis on the genus Pisidium. Environmental Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency. 144 pages.