 A major revision of the slug fauna published in 2014, partly based on genetic sequencing, established that there were 20% more species than had previously been recognised.Not all these species have been definitely identified and some are formally undescribed.In addition to the species that survive outdoors in Great Britain, there are also another 14 exotic gastropod species (some terrestrial and some aquatic) which live as "uninvited guests" in greenhouses and their enclosed aquaria.