Achatinellidae

Achatinellidae is a family of land snails belonging to the superfamily Pupilloidea. These snails are characterized by their dextral (right-handed) shells, which are typically ovate and smooth. The family is endemic to the Hawaiian Islands, where they inhabit a variety of ecological niches, from wet forests to drier, more exposed habitats.

The subfamily Achatinellinae is the most well-known and includes the iconic Achatinella species, often referred to as "Oʻahu tree snails." These snails are arboreal and were once abundant on the island of Oʻahu. Sadly, many species within this subfamily are now extinct or critically endangered due to habitat loss, introduced predators, and disease. Conservation efforts are underway to protect the remaining populations.

Another subfamily, Tornatellininae, also occurs in the Hawaiian Islands, with some species found on other Pacific islands. These snails are generally smaller than Achatinellinae and inhabit leaf litter and soil. While some species face threats, they are generally not as critically endangered as their tree-dwelling relatives.

The biology of Achatinellidae snails varies, but most are hermaphroditic. They play a role in their ecosystems as herbivores and detritivores, contributing to nutrient cycling. Their beautiful shells have also made them objects of interest for collectors, unfortunately leading to overcollection in the past. Research continues to understand their evolutionary history and ecological importance within the Hawaiian archipelago.