Bulla (gastropod)

Bulla
A shell of Bulla quoyii
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
(unranked): clade Heterobranchia
clade Euthyneura
clade Euopisthobranchia

clade Cephalaspidea

Superfamily: Bulloidea
(Lamarck, 1801)
Family: Bullidae
(Rafinesque, 1815)
Genus: Bulla
Linnaeus, 1758
Type species
Bulla ampulla
Linnaeus, 1758
Species

See text

Synonyms[1]
  • Bullaria Rafinesque, 1815
  • Quibulla Iredale, 1929
  • Vesica Swainson, 1840

Bulla is a genus of medium to large hermaphrodite sea snails, shelled marine opisthobranch gastropod molluscs. These herbivorous snails are in the suborder Cephalaspidea, headshield slugs, and the order Opisthobranchia.[1]

These snails are popularly known as "bubble snails", and their shells as "bubble shells", 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.

Shell description

shell of Bulla vernicosa

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.

Taxonomy

This family seems to have evolved separately in an early stage of the evolutionary history of the opisthobranchs. For a fuller treatment of the whole group see Cephalaspidea.

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 [2]

Species

A shell of Bulla ampulla
A shell of Bulla striata

Synonyms

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)[4][5]

References

  1. 1 2 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
  2. ↑ 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.
  3. ↑ Manuel 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, doi:10.1111/j.1096-3642.2008.00369.x
  4. ↑ http://species-identification.org/species.php?species_group=mollusca&menuentry=soorten&id=532&tab=synoniemen
  5. ↑ http://www.gastropods.com/5/Shell_5525.shtml
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