Calyptraeids

Calyptraeids are a family of marine gastropod mollusks commonly known as slipper shells or hat shells. They are characterized by their conical or cap-shaped shells, which are often cemented to hard substrates like rocks, pilings, or the shells of other animals. This sessile lifestyle is a defining feature of the calyptraeids.

These mollusks are found in temperate and tropical waters worldwide. They are filter feeders, using their ctenidia (gills) to strain plankton and other small particles from the water. Their feeding apparatus is adapted for their stationary existence, efficiently capturing food as it drifts by.

A remarkable aspect of calyptraeid biology is their reproductive strategy, which often involves sequential hermaphroditism. Many species are born male and later change to female as they mature. This ensures reproductive success within populations where finding a mate might be challenging due to their sedentary nature.

Calyptraeids play a role in marine ecosystems by filtering water and providing a substrate for other organisms to attach to. Some species can become quite numerous, forming dense aggregations that alter the local habitat. Their shells are typically calcareous and can vary in color and texture depending on the species and environmental conditions.