Bubble Shells of the Bullidae Family
One Bubble Shell of the Bullidae Family can be found in this website:
Gould’s Bubble Shell, Bulla gouldiana. A representative of the Bullidae Family of Bubble Shells.
Phylogeny: True Bubble Shells of the Bullidae Family are members of the order Cephalaspidea. Shells in this order are characterized by having a shovel-shaped shield structure on their heads. This shield keeps sand or mud from filling their mantle cavity as they push through the substrate. This trait has given them the name “headshield slugs.” True Bubble Shells are one of four families in the superfamily Bulloidea. The Bullidae Family consists of only one genus – Bulla. There are seventeen accepted species in this genus. These shells are called True Bubble Shells to distinguish them from similar looking shells in other families such as the in the Cylichnidae Family of Chalice Bubble Shells and the Retuside Family of Barrel Bubble Shells.
Description: True Bubble Shells are egg-shaped and thin shelled. They range in size from small to medium. They have exceedingly large body whorls that overgrow the spire leaving a depression or pit where the spire would have protruded. They do not have an operculum. They have long apertures that extend above the body whorl. The apertures lack teeth or folds, though the columella has callus. The aperture widens toward the anterior. The exterior of the shell is smooth and usually dark in color. To avoid predation True Bubble Shells can withdraw within their shell, unlike Paper Bubble Shells which do not fit within their shell. They may be pinkish, tan, brown, or gray in color, often with darker blotches. True Bubble Shells can reach 6.0 cm (2.3 inches) in length.
Habitat and Distribution: True Bubble Shells reside on sand, mud, and gravel substrates, often in beds of green algae and sea grasses. They are found intertidally and at depths in excess of 2,300 m (7,544 feet). They reside in tropical to temperate seas, worldwide.
Natural History: True Bubble Shells may be either depositional feeders, feeding on diatoms and algae cells that are deposited on the bottom, or herbivores, grazing on green algae. True Bubbles Shells have a soft radula and a well-developed gizzard to facilitate their vegetarian diet. They are preyed upon by shorebirds, crabs, sea stars, and predatory mollusks. In addition to withdrawing into their shells as a defense mechanism, many species can secrete a toxic chemical from the mantle that envelops their shells. They are simultaneous hermaphrodites and reproduce sexually with internal fertilization. They lay eggs in protective capsules, often in string-like masses. True Bubble Shells are generally nocturnal and some species have been very good models for research into circadian rhythms and neural biological timekeeping.