Species Fact Profile: Polynesian Tree Snail (Partula nodosa)

                                                                   Polynesian Tree Snail

                                                       Partula nodosa (Pfeiffer, 1851)

Range: Tahiti, French Polynesia (formerly: now extinct in the wild)

Habitat:  Forested slopes and valleys of volcanic islands

Diet: Decaying Plant Matter

Social Grouping:  Asocial

Reproduction: Cross-fertilizing hermaphrodites (self-fertilization rarely occurs).  Courtship consists of slowly approaching each other and making appropriate gestures, after which both animals will leave pregnant.  Give birth to live young, about 1-2 millimeters, growing to adulthood at 3-6 months of age.  Four life stages, largely identified by size – newborn, juvenile, sub-adult, and adult

Lifespan: 5-6 Years

      Conservation Status: IUCN Extinct in the Wild

• Partulid snails range from 1-2.5 centimeters in length.  Shells are spirals of grey, brown, white
• Primarily feeds at night. Daytime hours spent sticking to underside of leaves in shade to prevent drying out
• Has also been listed as a subspecies of Partula affinis (Partula affinis nodosa), but generally recognized as a separate species
• Historically there was some use of the shells in necklace making, but little significant trade
• Primary cause of decline is predation from the introduced carnivorous snail Euglandina rosea (rosy wolf snail) in 1977, which was in turn introduced to the islands to control the also-invasive giant African land snail (Lissacatina fulica), which was introduced as a human food source in 1967 but quickly became an agricultural pest.  Between the 1970s and 1990s, approximately two-thirds of the Partula snails were driven to extinction.  Today 56 of the 72 species are extinct, with an additional 10 only surviving in captivity. 26 surviving snails were collected from wild, sent to Detroit Zoo for nexus of captive breeding program
• Reintroduction efforts began in 2016 and were in place prior to the COVID pandemic, then placed on hold – hope to restart in the near future.  Reintroduction consists of erecting predator-proof barriers, removing invasive snails, and gradually expanding the safe zone
• The genus Partula has been used to study adaptive radiation in islands, similar to Darwin’s finches in the Galapagos Islands.