Description

Shells in this family are bubble shaped, dark colored, and have a sunken spire. The aperture is as long as the shell and usually comma shaped, while the columella has a callus without folds. The shells are very thin. None of the Bullidae have an operculum, and the mollusc can retract entirely within its shell. In this respect, the Bullidae differ substantially from other opisthobranchs like the Hydatinidae, whose shells are too small and fragile to provide either cover or protection for the whole mollusc. The Bullidae seem to have split off at an intermediate or earlier evolutionary stage, between the caenogastropod and the opisthobranch subclassses.

 

Members of the family inhabit sands in shallow water. Most feed on algae; some feed on invertebrates. Only one family is found in the suborder, Bullacea.

 

Some other shells within the subclass, Opisthobranchia, are paper-thin. The physical features of the shells are shared by numerous species among the different families (Acteonidae, Haminoeidae, Bullinidae, Hydatinidae, Diaphanidae, etc. Their taxonomic classification is not entirely settled, mainly because too little is known of the anatomy of any of the living mollusc species.

 

Classification

Class: Gastropoda

Informal Group : Opisthobranchia

Clade: Cephalaspidea

Suborder: Bulloidea

Family: Bullidae

Single Genus: Bulla

• Species: Bulla ampulla  
• Species: Bulla botanica (Australian Bubble)
• Species: Bulla gouldiana  
• Species: Bulla striata (Common Atlantic Bubble)

Bulla gouldiana (Pilsbry, 1895)
California Bubble

Bulla ampulla (Linn., 1758)
Ampulle Bulla

LINK --SEE THE LIVE MOLLUSC: