Marine snails 3 (IMAGE) University of Sheffield Caption Live-bearing has allowed Littorina snails to occupy and adapt to a diverse range of habitats. This has led to the evolution many ‘ecotypes’ that vary in their size, shape and behavior. Credit Fredrik Pleijel Usage Restrictions No restrictions. License Public Domain Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.