Black Sea Snail Facts

Black periwinkles are a type of marine snail. Periwinkles may live out of the water for several days and can survive in challenging conditions. Out of the water, they can stay moist by closing the trap doors on the opening of their shells. This is called an operculum. Periwinkles are herbivores that feed on algae such as, Green algae and diatoms. Green algae is common in areas where light is abundant, such as shallow water or rock pools. They use their radular (tiny teeth) to scrape algae off of rocks. Green algae can range from single-celled organisms to multi-celled organisms, such as Sea lettuce (Ulva Lactuca). They live in large colonies , close to water. Periwinkle’s diets consist mainly of green algae. On the day of our data collection, we noted that our transect on Broulee Island was facing south and was constantly exposed to sunlight during the daylight hours. During the time frame that we were there, the black periwinkles were moving towards the damper, unders and crevices of the rocks, or staying close to the three rock pools in our transect. This suggests that the rising temperature and the fact that the tide was in the process of coming in, effected the distribution and placement of the periwinkles. The periwinkles were found closer to the middle of our transect, as they were not in the ocean, but were still exposed to shallow rockpools and therefore had access to green algae. Black periwinkles are a type of marine snail. Periwinkles may live out of the water for several days and can survive in challenging conditions. Out of the water, they can stay moist by closing the trap doors on the opening of their shells. This is called an operculum. Periwinkles are herbivores that feed on algae such as, Green algae and diatoms. Green algae is common in areas where light is abundant, such as shallow water or rock pools. They use their radular (tiny teeth) to scrape algae off of rocks. Green algae can range from single-celled organisms to multi-celled