Littorinids

Littorinids are a family of marine gastropod mollusks commonly known as periwinkles. They belong to the superfamily Littorinoidea. These snails are typically found in intertidal zones, clinging to rocks and other hard surfaces, and are a common sight along coastlines worldwide. Their shells are usually coiled, conical, and often have a thick, rugose texture, though the specific shape and ornamentation vary significantly between species. Periwinkles are herbivores, grazing on algae and diatoms that grow on the rocks where they live.

The distribution of littorinids is extensive, with species found in temperate, subtropical, and tropical waters of all oceans. Many species are adapted to survive periods of emersion, enduring exposure to air and desiccation during low tide. This adaptation is crucial for their survival in the harsh intertidal environment. Reproduction in littorinids generally involves external fertilization, with females releasing eggs and males releasing sperm into the water column. The larval stages are planktonic, allowing for dispersal to new areas.

Littorinids play a role in their ecosystem by controlling algal growth and serving as a food source for various predators, including birds, fish, and other invertebrates. Some species are of economic importance, being harvested for food in certain regions. The family includes numerous genera and species, each with specific ecological requirements and geographic ranges. Their resilience and widespread presence make them important indicators of the health of intertidal ecosystems.