Bulla is a genus of medium to large hermaphrodite sea snails, shelled marine opisthobranch gastropod molluscs. These herbivorous snails are in the order Cephalaspidea.Gofas, S. (2010). Bulla Linnaeus, 1758. In: Bouchet, P.; Gofas, S.; Rosenberg, G. (2010) World Marine Mollusca database. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=137716 on 2011-05-04
These snails are popularly known as "bubble snails" because the shell of some of the species is very inflated indeed, almost spherical in shape, and is also very thin and light.
According to some experts, Bulla is currently the only genus in the family Bullidae, which in turn is the only member of the superfamily Bulloidea.
In addition to its taxonomic interest, Bulla — particularly Bulla gouldiana — has served as an important model organism in circadian biology research, where it has been used to investigate circadian rhythms, photoentrainment, and the neural basis of biological timekeeping, contributing to the broader understanding of biological rhythms and neural systems.
Taxonomy Bulla, Haminoea and Smaragdinella form the well-defined monophyletic group Bulloidea, according to the 1996 phylogenetic analysis of Paula M. Mikkelsen (Malacologia, 37(2): 375-442). But, according to Dr. Bill Rudman and others, differences in the alimentary canal and reproductive system, still put Haminoea and Smaragdinella into the separate superfamily Haminoeidea.
Historically, since the 18th century and even in the 20th century, the genus name Bulla has been used for a great number of bubble-shelled species that belonged to the order Cephalapsidea. From the mid-20th century, authors began to restrict species to the genus Bulla in its current meaning. But misidentifications were still numerous through high levels of intraspecific variability in the shell, radula and male genital system. The monograph by Malaquias & Reid (2008) has offered a systematic revision of this genus and has brought order in this genus Malaquias M.A. & Reid D.G. (2008). Systematic revision of the living species of Bullidae (Mollusca: Gastropoda: Cephalaspidea), with a molecular phylogenetic analysis. Zoological Journal of the Linnean Society 153:453-543.
Anatomy
Shell description All Bulla species have large, ovate external shells, which are large enough to accommodate the whole snail when retracted. All species have rather similarly shaped shells. The shells have a deep, narrow umbilicus at the apex. There is no operculum.
The smooth shell of Bulla is ovate and expanded, with a deep, sunken involute top. Since there is little difference between the shells and in the morphology of the radular teeth, there is some uncertainty about the exact taxonomy of the species in Bulla.
Anatomy of the soft parts The gizzard of Bulla is rather different from that of other herbivorous groups. It has three large corneous crushing plates and ancillary corneous spines, instead of just grinding plates. The crawling snails show prominent, frilled or lobed parapodia.
Bulla species have a soft radula.
Life habits These snails are mostly nocturnal and can be found on shallow, sandy coasts grazing among sea grasses, feeding primarily on green algae. They bury themselves in mud when the tide is out.
Predators In the coastal lagoons and bays of California, the colorful nudibranch Navanax inermis is a well-known predator of sea slugs, especially Bulla gouldiana, which it envelopes whole.
Species
Bulla ampulla Linnaeus, 1758 Pacific bulla, ampulle bulla Distribution : on sandy sublittoral bottoms of warmer seas, tropical Indo-Pacific, Pakistan, Sri Lanka, Philippines Length : 60 mm (largest shell of the Cephalaspidea) Description : This is the common Bulla in tropical Indo-Pacific; globose, inflated, moderately solid body whorl. The white aperture is as long as the rest of the shell.The rounded outer lip is extended posteriorly beyond the apex. Columella in a reversed 'S'-shape, smooth and thinly callous. Cream-colored with blotches of dark, purple-brown. Bulla arabica Malaquias & Reid, 2008Manuel Antonio E. Malaquias and David G. Reid Systematic revision of the living species of Bullidae (Mollusca: Gastropoda: Cephalaspidea), with a molecular phylogenetic analysis. Zoological Journal of the Linnean Society, Volume 153, Issue 3, Page 453-543, Jul 2008, Bulla bermudae Verrill and Bush, 1900 Distribution : Bermudas Length : 3 mm Bulla clausa Dall, 1889 imperforate bubble Distribution : Florida Length : 12 mm Bulla gouldiana Pilsbry, 1895 California bubble, Gould's bubble, cloudy bubble Distribution : Northwest America, California to Ecuador Length : 30–64 mm Description: semi-transparent head, mantle and foot are yellowish-brown with mottled pale-bluish dots; reddish to brown involute (= sunken) apex; the aperture is wide anteriorly, narrow posteriorly; their egg mass is yellow to orange tangled string of jelly, containing oval capsules. Each one contains up to 25 eggs, which develop into veliger larvae. Bulla indolens Dall, 1927 Distribution : Georgia Length : 7.5 mm Description : found at depths up to 800 m Bulla japonica T. Habe, 1976 Distribution : Japan Bulla krebsii Dall, 1889 Distribution : Guadeloupe Length : 8 mm Description : found at depths up to 1400 m Bulla mabillei E. A. A. Locard, 1896 Mabille's bubble Distribution : Turkey, Canaries, Madeira, Cape Verde, West Africa Length : 33–52 mm Description : larger than the other European species; difficult to obtain; color : yellowish-brown with dark bluish dots Bulla morgana Dall, 1908 Distribution : West America Bulla occidentalis A. Adams, 1850 (synonym of Bulla striata) common West Indian bubble Distribution : Brazil, North Carolina to Florida, Bahamas, Caribbean. Length : 25 mm Description : thin, rotund, oval shell with a smooth, glazed surface; pale color with brown spots; involute (= sunken) apex; large body whorl; long aperture, wide anteriorly; white columella. Bulla orientalis T. Habe, 1941 Distribution : Indo Pacific Description : brown punctuate marks on the shell Bulla peasiana Pilsbry, 1895 Bulla punctulata A. Adams In Sowerby, 1850 Distribution : Pacific, California, Mexico, Peru Length : 30 mm Description : the shell looks like the one of Bulla ampula, but is smaller and more cylindrical. Its color is cream, with clouding of brown or gray in two to four spiral bands, generally spotted with squarish chocolate dots, bordered to the right by white spots. Bulla quoyii Gray in Dieffenbach, 1843 brown bubble shell Distribution : Southern Australia, northern New Zealand. Length : 44 mm-60 mm Description :The calcified shell has a gray-brown color, with blotches of various shades of brown; the snail has a bright honey-golden color. The hind extremities of the headshield have evolved into tentacles, directing the water over Hancock's organ. The egg-mass is a jelly-like sphere, with the eggs in a spiral string. After the breeding period, there occurs a mass mortality of the animals, just like the sea hares. Bulla solida Gmelin, 1791 solid bubble Distribution : Mexico, Florida, Texas, Cuba, Colombia. Length : 30–52 mm Description : found at depths up to 25 m Bulla striata Bruguière, 1792 common Atlantic bubble, striate bubble Distribution : Mediterranean, Morocco, Canaries, Azores, Atlantic Ocean, Florida Length : 12–30 mm Description : The shell is thin, delicate and rather narrow. The body whorl is oval and convex. The smooth elongated aperture narrows posteriorly, but is wide anteriorly. The columellar callus is rather small; The thin outer lip is incurved and extends a little beyond the apex; The color is brown-gray, with darker, smudged dots and dashes, spread unevenly over the surface. The surface is smooth, with some spiral grooves at the posterior end and at the apical umbilicus. There is no operculum. The foot is well developed. There are no parapodia (fleshy winglike outgrowths). The broadened head has no tentacles. The gills and the osphradium are inside the mantle cavity. The radula has three laterals on each side of the central tooth. Bulla vernicosa Gould, 1859 (most probably a color variant of Bulla ampulla) Distribution : Indo Pacific, Thailand, Indonesia, Philippines, Taiwan, Tonga Length : 27–50 mm Description : white-colored shell with light brown spots
Other species In addition to the above, there are a substantial number of names in Bulla that apply to the species Akera bullata, including Bulla akera (Gmelin, J.F., 1791), Bulla norwegica (Bruguière, J.G., 1789), Bulla canaliculata (Olivi, 1792), Bulla resiliens (Donovan, E., 1801), Bulla fragilis (Lamarck, J.B.P.A. de, 1822), Bulla hanleyi (Adams A. in Sowerby G.B. II, 1850/1855), Bulla elastica (Sandri & Danilo, 1856), Bulla farrani (Norman, 1890), Bulla globosa (Cantraine, F.J., 1840)
Synonyms
Bulla abyssicola Dall, 1881 (junior synonym of Bulla pinguicula) Bulla achatina Linnaeus, 1758: synonym of Achatina achatina (Linnaeus, 1758) Bulla acuminata Bruguière, 1792: synonym of Volvulella acuminata (Bruguière, 1792) Bulla acuta d'Orbigny, 1841: synonym of Volvulella minuta (Bush, 1885) Bulla adansonii Philippi, 1847 : synonym of Bulla striata Bruguière, 1792 Distribution: West Africa, Gabon, Cape Verde Length : 15 mm Bulla akera Gmelin, 1791: synonym of Akera bullata O. F. Müller, 1776 Bulla alba Turton, 1825: synonym of Bulla striata Bruguière, 1792 Bulla albocincta van der Hoeven, 1839: synonym of Hydatina albocincta (van der Hoeven, 1839) Bulla algirae A. Adams in G. B. Sowerby II, 1850: synonym of Melanochlamys algirae (A. Adams in G. B. Sowerby II, 1850) Bulla amplustre Linnaeus, 1758: synonym of Aplustrum amplustre (Linnaeus, 1758) Bulla amygdala Dillwyn, 1817 : synonym of Bulla striata Distribution: Canaries, East Atlantic, Mediterranean, Florida, Brazil Length : 40 mm Bulla amygdalum Dillwyn, 1817: synonym of Bulla striata Bruguière, 1792 Bulla amygdalus Dillwyn, 1817: synonym of Bulla striata Bruguière, 1792 Bulla angasi Pilsbry, 1893 : synonym of Bulla mabillei Locard, 1897 Distribution: Australia Length: 25 mm Description: smooth, sturdy, cylindrical shell; color : dark brown Bulla antillarum d'Orbigny, 1841: synonym of Haminoea antillarum (d'Orbigny, 1841) Bulla aperta Linnaeus, 1767: synonym of Philine aperta (Linnaeus, 1767) Bulla arachis Quoy & Gaimard, 1833: synonym of Adamnestia arachis (Quoy & Gaimard, 1833) Bulla aspersa A. Adams, 1850: synonym of Bulla punctulata A. Adams in Sowerby, 1850 Bulla atrolineata Schröter, 1804: synonym of Hydatina physis (Linnaeus, 1758) Bulla aurisjudae Linnaeus, 1758: synonym of Ellobium aurisjudae (Linnaeus, 1758) Bulla aurismidae Linnaeus, 1758: synonym of Ellobium aurismidae (Linnaeus, 1758) Bulla australis Gray, 1825: synonym of Bulla quoyii Gray, 1843 Bulla australis Quoy & Gaimard, 1833: synonym of Bulla quoyii Gray, 1843 Bulla bidentata d'Orbigny, 1841: synonym of Cylichnella bidentata (d'Orbigny, 1841) Bulla biplex A. Adams, 1850: synonym of Truncacteocina biplex (A. Adams, 1850) Bulla biplicata A. Adams, 1850 (synonym of Acteocina bidentata (d'Orbigny, 1841)) Distribution : Japan, New Jersey, North Carolina, Florida, Caribbean, Brazil, Uruguay Length : 4 mm Bulla birostris Linnaeus, 1767: synonym of Phenacovolva birostris (Linnaeus, 1767) Bulla bizona A. Adams, 1850: synonym of Mnestia bizona (A. Adams, 1850) Bulla blainvilliana Récluz, 1843: synonym of Atys jeffreysi (Weinkauff, 1866) Bulla blainvilliana Récluz, 1843: synonym of Cylichnina umbilicata (Montagu, 1803): synonym of Retusa umbilicata (Montagu, 1803) Bulla botanica Ch. Hedley, 1918 Australian true bubble, common true bubble : synonym of Bulla quoyii Gray, 1843 Distribution : Australia Length : 32–55 mm Bulla brevis Quoy & Gaimard, 1833: synonym of Liloa brevis (Quoy & Gaimard, 1833)