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Bermuda land snails, scientific name ''Poecilozonites'', are an endemic genus of pulmonate land snail in the family Gastrodontidae (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005). Scientists believe that ''Poecilozonites'' colonised the mid-Atlantic island of Bermuda at least 300,000 years ago. ''Poecilozonites'' makes up 95% of Bermuda's terrestrial fossils. Only one other large pulmonate, ''Succinea'', has been found as a fossil. ==Research== The major contributor to the natural history of ''Poecilozonites'' was Harvard paleontologist Stephen Jay Gould who did his doctorate and early academic research on Bermuda's snails. On December 21, 1999, Dr. Gould described to ''The Royal Gazette'' of first visiting Bermuda as a deckhand on a Woods Hole Research Center boat in 1959. "I was a geology major. I had a look around and found all these wonderful fossil snails in all their variety. The geology of Bermuda had already been worked out by then and I thought these snails would become a pretty good PhD." ''Poecilozonites'' is a member of the Gastrodontidae family and is likely to have colonised Bermuda from North America as one specimen via flotsam. Gould cites research which uses the "probability of self-impregnation" as the justification of this view. Gould claims the proto-''poecilozonites'' "underwent a vigorous and presumably rapid adaptive radiation" and diversified into three subgenera and 15 species, ranging in size from ''P. nelsoni'' (max dia. 46 mm) to the subspecies' of ''P. gastrelasmus'' and ''P. discozonites'' which were found to rarely exceed 5 mm. Although extinction of various species occurred in prehistoric times, with the introduction of predators by man in the 16th century, namely hogs, dogs, cats, and rats, the snail suffered, but has apparently hung on. It was the introduction of the predator snails ''Euglandina'' and ''Gonaxis'' in the 1950s and 1960s and the increased use of pesticides that led to the presumed extinction of the surviving ''Poecilozonites species by the 1970s. The apparently accidental introduction of the edible snail, ''Otala'' in the mid-1920s set the die for the destruction of ''Poecilozonites'' as by the 1950s, ''Otala'' had become a pest and measures were taken to control their numbers. By the time of Gould's research in the mid-1960s, ''P. bermudensis'' and ''P. circumfirmatus'' were still common. He wrote of talking to an elderly woman who remembered a time when the shells were collected and burned for lime. By the mid-1970s, a Bermuda Biological Station scientist remembers opening his kitchen door and seeing none other than Gould exclaim "If I could only find one alive!" In "Eight Little Piggies," a book from 1993, Gould wrote: "I don't even think ''Euglandina'' has even dented ''Otala'' but it devastated the native ''Poecilozonites''. I used to find them by the thousands throughout the Island. When I returned in 1973... I could not find a single animal alive. Last year (1991) I relocated one species, the smallest and most cryptic, but the large ''P. bermudensis'', the major subject of my research, is probably extinct." In 2002, a Bermuda Aquarium, Museum and Zoo summer intern, Alex Lines, was sent out to Gould's old sites and is understood to have found a clutch of survivors. Several dozen snails were sent to London to aid their propagation. ''Poecilozonites circumfirmatus'' is protected in Bermuda under the Protected Species Act (2003) and a Protected Species Recovery Plan was published for it in 2010 by the Bermuda Government, Department of Conservation Services. In 2014 it was reported in The Royal Gazette that a live colony of ''Poecilozonites bermudensi'' had been found in the City of Hamilton.〔http://www.bbc.com/news/blogs-news-from-elsewhere-29790073〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Bermuda land snail」の詳細全文を読む スポンサード リンク
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