Mactrids

Mactrids are a family of marine bivalve mollusks that are commonly found in coastal waters around the world. The name "mactrid" is derived from the genus Mactra, which is one of the most well-known genera within the family.

Mactrids are characterized by their elongated shells, which are typically rounded at the posterior end and flattened at the anterior end. They often have distinct lines or ridges on their dorsal surfaces, which are thought to be used for burrowing and attachment to the substrate. Mactrids can range in size from a few millimeters to several centimeters in length, with the largest species reaching up to 15 centimeters in length.

Mactrids are primarily filter feeders, using their siphons to draw in water and filter out small particles such as plankton and detritus. This feeding behavior allows them to play a key role in maintaining the health of coastal ecosystems by helping to regulate the populations of zooplankton and other small organisms.

Mactrids can be found in a variety of habitats, including sandy and muddy substrates, as well as in more rocky areas with suitable crevices for anchorage. They are generally found in shallow waters, typically between 0 and 100 meters in depth, although some species may be more tolerant of deeper water. Overall, mactrids are an important component of coastal ecosystems and play a key role in the marine food chain.