Moon Shells of the Naticidae Family

Seven Moon Shells of the Naticidae Family can be found in this website:

Phylogeny: Moon Shells of the Naticidae Family are gastropod mollusks in the Littorinimorpha order. This order is large and very diverse in shape including snail-like, cowry shaped, and limpet-like. Most are marine species but some are found in freshwater or on land. They all have a twisted shell and a muscular foot that is used for movement. The key characteristic is that they all exhibit torsion, which is a process where the body twists so that the anus, gills, mantle cavity, and reproductive organs all point forward. There are sixteen superfamilies in this large order. The Naticidae Family is the only family in the superfamily Naticoidea. Naticidae is a large family comprised of five subfamilies, thirty-seven genera, and around three hundred seventy species. These shells are also commonly called Naticids.

Description: Moon Shells have globular to disk-shaped shells that may be thin or thick and range from very small to large in size. They have large body whorls and very short spires.  The exterior of these shells is generally smooth and may be somewhat polished. Some species have weak commarginal grooves along the shoulders. The aperture is ovate to semi-circular. The interior is porcelaneous. Moon Shells have an umbilicus, but often it is covered by callus. The operculum can be calcareous, or horn-like, in substance. They lack a periostracum. The mantle of Moon Shells is large and able to cover the shell, keeping it polished. In many species, the animal is too large to fit completely into the shell, until they expel a large amount of water. Larger species in this family can exceed 13 cm (5 inches) in length.

Habitat and Distribution: Moon Shells are found on mud or sand bottoms. They are found from the intertidal zone to depths up to 300 m (1,000 feet). Moon Shells are found worldwide in tropical to polar seas. There are twenty species of Moon Shells found in Mexican waters.

Natural History:  Moon Shells are highly predatory, plowing through the sand in search of bivalves or other snails. Once located the victim is enclosed in their foot and the radula is used to drill a round beveled hole into the other shell. A chelating compound to weaken the other shell is released to facilitate drilling. The process kills the prey which is then consumed by the Moon Shell. In return Moon Shells are preyed upon by shorebirds, crabs, fish, mollusks and sea stars. They are gonochoric and reproduce sexually with internal fertilization. The eggs are usually laid in capsules embedded within an egg collar. The mantle is used in the construction of the egg collar, a wide ribbon of sand and mucous that forms a broken loop. The egg capsules are deposited on the inside surface of the loop. Then another layer of sand and mucous is placed over the eggs, sealing them inside. Once the eggs develop into larvae, they break out of the collar. The collar stays flexible, like thin plastic throughout the process. Moon Shells are edible and are harvested by artisanal and small commercial fisheries.

Moon Shell Egg Case. A representative sample of a Moon Shell Egg Case from the Naticidae Family of Moon Shells. Photograph and identification courtesy of Ron Woheau, Zihuantanejo, January 2019. Ron’s brother Juanito reports seeing similar Egg Cases in the Yal Ku area, Quintana Roo, of the Yucatán Peninsula.