Achatinellidae

Achatinellidae is a family of tropical air-breathing land snails, terrestrial pulmonate gastropod mollusks in the superfamily Achatinelloidea. This is the only family in the superfamily Achatinelloidea (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005). The family Achatinellidae represents a diverse adaptive radiation. All species of tree-snail in Hawaii are believed to have come from a single ancestral snail. How that ancestral snail made the 3,800 kilometres (2,400 mi) trip across the ocean is unknown. A longstanding theory is that a bird carried a notably smaller ancestor across the ocean and dropped it on the islands, as bird mediated dispersal has been documented in other snail species. Alternative theories include that it floating across the ocean on a mat of debris, or that it island hopped across the Pacific in a combination of the theories.