Bermuda Land Snail
Encyclopedia
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 have colonised the mid-Atlantic island of Bermuda
at least 300,000 years ago. It makes up 95% of Bermuda's terrestrial fossil
s. Only one other large pulmonate Succinea
has been found - as a fossil
.
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, dog
s, cat
s, and rat
s, 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 pesticide
s 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 have been 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.
subgenus Poecilozonites
subgneus ?
Endemic (ecology)
Endemism is the ecological state of being unique to a defined geographic location, such as an island, nation or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, all species of lemur are endemic to the...
genus of pulmonate land snail in the family Gastrodontidae
Gastrodontidae
Gastrodontidae is a family of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the clade Eupulmonata ....
(according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005
Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005)
The taxonomy of the Gastropoda as it was revised by Philippe Bouchet and Jean-Pierre Rocroi is currently the most up-to-date overall system for classifying gastropod mollusks...
).
Scientists believe, that Poecilozonites have colonised the mid-Atlantic island of Bermuda
Bermuda
Bermuda is a British overseas territory in the North Atlantic Ocean. Located off the east coast of the United States, its nearest landmass is Cape Hatteras, North Carolina, about to the west-northwest. It is about south of Halifax, Nova Scotia, Canada, and northeast of Miami, Florida...
at least 300,000 years ago. It makes up 95% of Bermuda's terrestrial fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s. Only one other large pulmonate Succinea
Succinea
Succinea, common name amber snails, is a genus of small, air-breathing, land snails, terrestrial pulmonate gastropod molluscs in the family Succineidae.They usually live in damp habitats such as marshes.-Species:...
has been found - as a fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
.
Research
The major contributor to the natural history of Poecilozonites is Harvard paleontologist Stephen Jay GouldStephen Jay Gould
Stephen Jay Gould was an American paleontologist, evolutionary biologist, and historian of science. He was also one of the most influential and widely read writers of popular science of his generation....
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
Woods Hole Research Center
The Woods Hole Research Center addresses pressing environmental issues, including climate change, through scientific and policy initiatives. The Center has projects in the Amazon, the Arctic, Africa, Russia, Alaska, Canada, New England, and the Mid-Atlantic, working in collaboration with a wide...
boat in 1959. "I was a geology
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
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
Gastrodontidae
Gastrodontidae is a family of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the clade Eupulmonata ....
family and is likely to have colonised Bermuda from North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
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
Adaptive radiation
In evolutionary biology, adaptive radiation is the evolution of ecological and phenotypic diversity within a rapidly multiplying lineage. Starting with a recent single ancestor, this process results in the speciation and phenotypic adaptation of an array of species exhibiting different...
" and diversified into three subgenera and 15 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, 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, dog
Dog
The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...
s, cat
Cat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
s, and rat
Rat
Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...
s, the snail suffered, but has apparently hung on.
It was the introduction of the predator snails Euglandina
Euglandina
Euglandina is a genus of medium- to large-sized land snails in the family Spiraxidae.These snails were previously placed in the family Oleacinidae , Spiraxidae and also in Streptaxidae.Euglandina is the type genus of the subfamily Euglandininae...
and Gonaxis
Gonaxis
Gonaxis is a genus of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Streptaxidae.- Distribution :Distribution of the genus Gonaxis include Equatorial Africa and South Africa:* South Africa* Tanzania...
in the 1950s and 1960s and the increased use of pesticide
Pesticide
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
s that led to the presumed extinction
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
of the surviving Poecilozonites species by the 1970s.
The apparently accidental introduction of the edible snail, Otala
Otala
Otala is a genus of large air-breathing land snails, terrestrial pulmonate gastropod mollusks in the family Helicidae. Archaeological recovery in Morocco indicates the exploitation of this genus by ancient Romans.-Distribution:...
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
Eight Little Piggies
Eight Little Piggies is the sixth volume of collected essays by the Harvard paleontologist Stephen Jay Gould. The essays were selected from his monthly column "The View of Life" in Natural History magazine, to which Gould contributed for 27 years...
," 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
Bermuda Aquarium, Museum and Zoo
The Bermuda Aquarium, Museum & Zoo is a facility located in Flatts Village, Bermuda, about 700 miles East of the United States and at the geographic center of Bermuda...
summer intern
Intern
Internship is a system of onthejob training for white-collar jobs, similar to an apprenticeship. Interns are usually college or university students, but they can also be high school students or post graduate adults seeking skills for a new career. They may also be as young as middle school or in...
, Alex Lines, was sent out to Gould's old sites and is understood to have found a clutch of survivors. Several dozen snails have been sent to London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...
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.
Species
Species in the genus Poecilozonites include:subgenus Poecilozonites
- ...
subgneus ?
- Poecilozonites bermudensis
- Poecilozonites capula
- Poecilozonites circinfinata
- Poecilozonites circumfimatus
- Poecilozonites circumfiranatus
- Poecilozonites circumfirinatus
- Poecilozonites circumfirmatus
- Poecilozonites circumfirmetus
- Poecilozonites circumfirnatus
- Poecilozonites circumformatus
- Poecilozonites circumfornatus
- Poecilozonites cupla
- Poecilozonites cupula
- Poecilozonites discrepans
- Poecilozonites egg
- Poecilozonites goodei
- Poecilozonites gulicki
- Poecilozonites heilprini
- Poecilozonites matjoriae
- Poecilozonites neksini
- Poecilozonites nelsoni
- Poecilozonites reimanus
- Poecilozonites reinianus
- Poecilozonites remiana
- Poecilozonites remianus
- Poecilozonites vanattae
- Poecilozonites vanattai
- Poecilozonites zonata
- Poecilozonites zonatus