Sun Dial Shells of the Architectonicidae Family
One Sun Dial Shell of the Architectonicidae Family can be found in this website:
American Sun Dial Shell, Architectonica nobilis. A representative of the Architectonicidae Family of Sun Dial Shells.
Phylogeny: The Architectonicidae Family of Sun Dial Shells is comprised of Lower Heterobranch gastropod mollusks. Lower Heterobranchs are specialized sea slugs and sea snails that include the sundial, pyramid, rissoella and orbitestellid families of snails. The Lower Heterobranch infraclass is considered a temporary status, awaiting revision. The superfamily Architectonicoidea is one of six superfamilies in this infraclass. There are three families in this superfamily. The Architectonicidae Family is medium-sized, with no subfamilies, twelve genera and one hundred twenty-four species. This family name comes from the Greek word “arkitekton” meaning master builder. This name refers to the resemblance that these intricate and beautiful shells share with architectural designs. The common name sun dial shells refers to the pattern on their spires. Another common name, Staircase Shells, refers to the unique sculpting of their umbilici (hole in bottom of their shell).
Description: Shells in this family are small to medium in size with few species reaching over 5 cm (2.0 inches) in diameter. They are round in outline, and have a low conical or discoidal profile. Most are low-spired, with a fairly blunt apex. They may be smooth or sculpted with with a spiral cords or striae, which may be beaded. The umbilicus is generally wide and sculpted like a spiral staircase. The umbilicus may be offset by a heavier cord. The aperture is ovate, though some have an angular outer lip. There may be one or more channels in the columella. These shells may be drab or intricately decorated with spots, checks, lines, and/or marbling. Most are found with earth-tone colors but some have red, purple and other brighter colors. They generally have flat opercula. Some deep water species in this family are minute, while the largest shallow water species can reach a maximum of 8.2 cm (3.2 inches) in diameter.
Habitat and Distribution: Some species of Sundial Shells are found on sand and have a sharp peripheral that facilitates burrowing. Others are found on rock, coral and other hard substrates. Sundial Shells range from the intertidal zone to depths in excess to 720 m (2362 feet). Because they have long larval phases, most species are very widely distributed. Sundial Shells are found worldwide in tropical and subtropical waters, with the greatest concentration of species being found in the Indo-Pacific. Eleven species from the Architectonicidae Family are found in Mexican waters.
Natural History: Sundial Shells are suctorial feeders that feed on sea anemones, zoanthids, and coral polyps. They feed by rasping a hole in the polyp with their radula and sucking out the fluids and tissue. In turn they are preyed on by shorebirds, crabs and fish. Shells in this family cover several options of reproductive modes. They may be gonochoric, simultaneous hermaphrodites or consecutive hermaphrodites. They reproduce sexually, with internal fertilization. The eggs are deposited in soft, gelatinous sausage-shaped masses attached to the substrate. Some species in this family can swim short distances by using their foot.