When discussing mollusks with members of our staff, volunteers, and visitors, I always caution them that sweeping generalizations about our beloved animals almost never work. We should be prudent and avoid saying “all marine snails have gills,” or “clams always make their homes on sand,” and so on. Exceptions abound! A standard example includes the members of the gastropod family Juliidae, minute marine snails that have their shells consisting of two separate hinged parts, or valves, just like a small clam! Not surprisingly, they were considered to be bivalves until the mid-20th century, when the first living juliid was observed by Japanese malacologists. Most members of the family live and feed on green seaweed of the genus Caulerpa, and their shells and bodies usually have the bright green color of their seaweed hosts. The photo shows Julia exquisita, a bivalved snail that attains about 7 mm (0.28 inch) in length. It was photographed in 2016 by Alexandre Laporte on Réunion Island, Indian Ocean. The image is distributed by Wikimedia Commons via a Creative Commons Attribution-Share Alike 4.0 International license.
A Bivalved Snail?
Julia exquisita, photo by Alexandre Laporte, Réunion Island, Indian Ocean.