Gillia altilis
Encyclopedia
Gillia altilis, common name
the Buffalo pebblesnail, is a species
of freshwater snail
, an aquatic
gastropod mollusk with an operculum
in the family Lithoglyphidae
.
Gillia altilis is the only species in the genus Gillia.
of this species is inflated but still conical. The shell color is usually yellow to green. The shell has 2–4 whorls
when eroded, and ~4.5 when intact. Each whorl is distinctly shouldered. The umbilicus is either not apparent, or very small. The columella is not thickened, and the shell itself can be thin or thick. The shell aperture
is oval to ear-shaped. When viewed laterally, the outer lip of the shell bends forward.
The height of the shell is 6–8 mm (– in).
The operculum
is chitin
ous, oval, yellow to green in color and shows paucispiral markings, with a subcentral nucleus.
is black, or shows dark pigmentation. This pigmentation is also seen in the nape, the anterior part of the snout
, the top of the tentacle
s, and along the edge of the peristome
(the margin of the gastropod shell).
The radula
of Gillia altilis looks like a single serrated blade, with 51-55 rows of teeth. Each row has 2 central basocones, 3-4 central octocones, 8-9 lateral teeth, ca. 30 inner marginal teeth and 6-9 outer marginal teeth.
. It occurs from New York State and Vermont
south to South Carolina
.
In some regions where Gillia altilis is native, populations are declining or not very abundant: for example, in Vermont, this species is considered to be an invertebrate species in “greatest conservation need”.
This snail is listed as a species of special concern
in its native range in New York State, where the species is ranked as S1 (very vulnerable due to low abundance of species and/or required habitat), protected U SC (unprotected at present but of special concern due to increasing evidence of vulnerability) and globally as G5 (rare but not vulnerable). Loss of habitat
due to anthropogenic modifications, pesticides and competition with introduced species are considered the major threats to declining or vulnerable gastropod populations in New York State.
drainage was from Oneida Lake
, New York State, around 1915–1918. However, in subsequent years it was likely extirpated from this water body.
Gillia altilis was able to colonize the Lake Ontario
drainage basin by means of the Erie Canal
system in New York State, which connects this part of the Great Lakes with the Hudson River
.. The snail was later recorded from Niagara-on-the-Lake
, Lake Ontario
, in 1936, and in the Erie Canal
at various times before 1940. Gillia altilis is considered established in the Lake Ontario drainage.
The New York State Department of Environmental Conservation
also reports records from Lake Erie
, but gives no references and declares that the current status of this population is unknown.
At this time, there are no recorded negative impacts in the Great Lakes system. There are also no known impacts in other water bodies at present.
stream
environments. Its globose shell is adapted for inhabiting high-velocity lotic environments (rheophile
animal), because it allows for a large, muscular foot that can suction to rocks. However, relatives of this species, with the same globose shell and large foot, are well adapted to living on silty substrates because the large foot prevents the snail from sinking. In fact, it is not uncommon for Gillia altilis to inhabit both stagnant waters in lakes and streams and rapidly moving waters. In Vermont, it is found in the Hudson River
in shoals where there is macrophyte cover and mud substrate. In New York State, it also commonly inhabits warmwater, shallow lacustrine habitats with mud substrate.
that is specialized, exhibiting overall larger but fewer cones and cusps on the various teeth, which are adapted for grazing on coarser food particles than are eaten by related snails in the subfamily Lithoglyphinae.
The egg capsules are ~1.25 mm in diameter.
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
the Buffalo pebblesnail, is a 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...
of freshwater snail
Freshwater snail
A freshwater snail is one kind of freshwater mollusc, the other kind being freshwater clams and mussels, i.e. freshwater bivalves. Specifically a freshwater snail is a gastropod that lives in a watery non-marine habitat. The majority of freshwater gastropods have a shell, with very few exceptions....
, an aquatic
Aquatic animal
An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...
gastropod mollusk with an operculum
Operculum (gastropod)
The operculum, meaning little lid, is a corneous or calcareous anatomical structure which exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails...
in the family Lithoglyphidae
Lithoglyphidae
Lithoglyphidae is a family of small freshwater snails with gills and an operculum, aquatic gastropod mollusks.This family is in the superfamily Rissooidea and in the clade Littorinimorpha .- Taxonomy :Taylor , Ponder & Warén and Kabat & Hershler considered this taxon as a subfamily...
.
Gillia altilis is the only species in the genus Gillia.
Shell description
The shellGastropod shell
The gastropod shell is a shell which is part of the body of a gastropod or snail, one kind of mollusc. The gastropod shell is an external skeleton or exoskeleton, which serves not only for muscle attachment, but also for protection from predators and from mechanical damage...
of this species is inflated but still conical. The shell color is usually yellow to green. The shell has 2–4 whorls
Whorl (mollusc)
A whorl is a single, complete 360° revolution or turn in the spiral growth of a mollusc shell. A spiral configuration of the shell is found in of numerous gastropods, but it is also found in shelled cephalopods including Nautilus, Spirula and the large extinct subclass of cephalopods known as the...
when eroded, and ~4.5 when intact. Each whorl is distinctly shouldered. The umbilicus is either not apparent, or very small. The columella is not thickened, and the shell itself can be thin or thick. The shell aperture
Aperture (mollusc)
The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where part of the body of the animal emerges for locomotion, feeding, etc....
is oval to ear-shaped. When viewed laterally, the outer lip of the shell bends forward.
The height of the shell is 6–8 mm (– in).
The operculum
Operculum (gastropod)
The operculum, meaning little lid, is a corneous or calcareous anatomical structure which exists in many groups of sea snails and freshwater snails, and also in a few groups of land snails...
is chitin
Chitin
Chitin n is a long-chain polymer of a N-acetylglucosamine, a derivative of glucose, and is found in many places throughout the natural world...
ous, oval, yellow to green in color and shows paucispiral markings, with a subcentral nucleus.
Anatomy
The mantleMantle (mollusc)
The mantle is a significant part of the anatomy of molluscs: it is the dorsal body wall which covers the visceral mass and usually protrudes in the form of flaps well beyond the visceral mass itself.In many, but by no means all, species of molluscs, the epidermis of the mantle secretes...
is black, or shows dark pigmentation. This pigmentation is also seen in the nape, the anterior part of the snout
Snout
The snout, or muzzle, is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw.-Terminology:The term "muzzle", used as a noun, can be ambiguous...
, the top of the tentacle
Tentacle
A tentacle or bothrium is one of usually two or more elongated flexible organs present in animals, especially invertebrates. The term may also refer to the hairs of the leaves of some insectivorous plants. Usually, tentacles are used for feeding, feeling and grasping. Anatomically, they work like...
s, and along the edge of the peristome
Peristome
The word peristome is derived from the Greek peri, meaning 'around' or 'about', and stoma, 'mouth'. It is a term used to describe various anatomical features that surround an opening to an organ or structure. The term is used in plants and invertebrate animals, such as in describing the shells of...
(the margin of the gastropod shell).
The radula
Radula
The radula is an anatomical structure that is used by molluscs for feeding, sometimes compared rather inaccurately to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters the esophagus...
of Gillia altilis looks like a single serrated blade, with 51-55 rows of teeth. Each row has 2 central basocones, 3-4 central octocones, 8-9 lateral teeth, ca. 30 inner marginal teeth and 6-9 outer marginal teeth.
Indigenous distribution
Gillia altilis is native to the Atlantic coastal drainage of North AmericaNorth 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...
. It occurs from New York State and Vermont
Vermont
Vermont is a state in the New England region of the northeastern United States of America. The state ranks 43rd in land area, , and 45th in total area. Its population according to the 2010 census, 630,337, is the second smallest in the country, larger only than Wyoming. It is the only New England...
south to South Carolina
South Carolina
South Carolina is a state in the Deep South of the United States that borders Georgia to the south, North Carolina to the north, and the Atlantic Ocean to the east. Originally part of the Province of Carolina, the Province of South Carolina was one of the 13 colonies that declared independence...
.
In some regions where Gillia altilis is native, populations are declining or not very abundant: for example, in Vermont, this species is considered to be an invertebrate species in “greatest conservation need”.
This snail is listed as a species of special concern
Species of special concern
Several organisations and government acts designate species of special concern. Among them are:* California species of special concern* The Canadian Species at Risk Act...
in its native range in New York State, where the species is ranked as S1 (very vulnerable due to low abundance of species and/or required habitat), protected U SC (unprotected at present but of special concern due to increasing evidence of vulnerability) and globally as G5 (rare but not vulnerable). Loss of habitat
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...
due to anthropogenic modifications, pesticides and competition with introduced species are considered the major threats to declining or vulnerable gastropod populations in New York State.
Nonindigenous distribution
The first record of Gillia altilis in the Great LakesGreat Lakes
The Great Lakes are a collection of freshwater lakes located in northeastern North America, on the Canada – United States border. Consisting of Lakes Superior, Michigan, Huron, Erie, and Ontario, they form the largest group of freshwater lakes on Earth by total surface, coming in second by volume...
drainage was from Oneida Lake
Oneida Lake
Oneida Lake is the largest lake entirely within New York State . The lake is located northeast of Syracuse and near the Great Lakes. It serves as one of the links in the Erie Canal. It empties into the Oneida River which flows into the Oswego River which in turn flows into Lake Ontario...
, New York State, around 1915–1918. However, in subsequent years it was likely extirpated from this water body.
Gillia altilis was able to colonize the Lake Ontario
Lake Ontario
Lake Ontario is one of the five Great Lakes of North America. It is bounded on the north and southwest by the Canadian province of Ontario, and on the south by the American state of New York. Ontario, Canada's most populous province, was named for the lake. In the Wyandot language, ontarío means...
drainage basin by means of the Erie Canal
Erie Canal
The Erie Canal is a waterway in New York that runs about from Albany, New York, on the Hudson River to Buffalo, New York, at Lake Erie, completing a navigable water route from the Atlantic Ocean to the Great Lakes. The canal contains 36 locks and encompasses a total elevation differential of...
system in New York State, which connects this part of the Great Lakes with the Hudson River
Hudson River
The Hudson is a river that flows from north to south through eastern New York. The highest official source is at Lake Tear of the Clouds, on the slopes of Mount Marcy in the Adirondack Mountains. The river itself officially begins in Henderson Lake in Newcomb, New York...
.. The snail was later recorded from Niagara-on-the-Lake
Niagara-on-the-Lake
Niagara-on-the-Lake is a Canadian town located in Southern Ontario where the Niagara River meets Lake Ontario in the Niagara Region of the southern part of the province of Ontario. It is located across the Niagara river from Youngstown, New York, USA...
, Lake Ontario
Lake Ontario
Lake Ontario is one of the five Great Lakes of North America. It is bounded on the north and southwest by the Canadian province of Ontario, and on the south by the American state of New York. Ontario, Canada's most populous province, was named for the lake. In the Wyandot language, ontarío means...
, in 1936, and in the Erie Canal
Erie Canal
The Erie Canal is a waterway in New York that runs about from Albany, New York, on the Hudson River to Buffalo, New York, at Lake Erie, completing a navigable water route from the Atlantic Ocean to the Great Lakes. The canal contains 36 locks and encompasses a total elevation differential of...
at various times before 1940. Gillia altilis is considered established in the Lake Ontario drainage.
The New York State Department of Environmental Conservation
New York State Department of Environmental Conservation
The New York State Department of Environmental Conservation is responsible for the conservation, improvement, and protection of natural resources within the U.S. state of New York. It was founded in 1970, replacing the previous Conservation Department...
also reports records from Lake Erie
Lake Erie
Lake Erie is the fourth largest lake of the five Great Lakes in North America, and the tenth largest globally. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and therefore also has the shortest average water residence time. It is bounded on the north by the...
, but gives no references and declares that the current status of this population is unknown.
At this time, there are no recorded negative impacts in the Great Lakes system. There are also no known impacts in other water bodies at present.
Habitat
Gillia altilis is usually found in freshwaterFreshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...
stream
Stream
A stream is a body of water with a current, confined within a bed and stream banks. Depending on its locale or certain characteristics, a stream may be referred to as a branch, brook, beck, burn, creek, "crick", gill , kill, lick, rill, river, syke, bayou, rivulet, streamage, wash, run or...
environments. Its globose shell is adapted for inhabiting high-velocity lotic environments (rheophile
Rheophile
A rheophile is an organism that prefers to live in fast moving water.-Insects:*Many aquatic insects living in riffles require current to survive.*Epeorus sylvicola, a rheophilic mayfly species .-Fish:...
animal), because it allows for a large, muscular foot that can suction to rocks. However, relatives of this species, with the same globose shell and large foot, are well adapted to living on silty substrates because the large foot prevents the snail from sinking. In fact, it is not uncommon for Gillia altilis to inhabit both stagnant waters in lakes and streams and rapidly moving waters. In Vermont, it is found in the Hudson River
Hudson River
The Hudson is a river that flows from north to south through eastern New York. The highest official source is at Lake Tear of the Clouds, on the slopes of Mount Marcy in the Adirondack Mountains. The river itself officially begins in Henderson Lake in Newcomb, New York...
in shoals where there is macrophyte cover and mud substrate. In New York State, it also commonly inhabits warmwater, shallow lacustrine habitats with mud substrate.
Feeding habits
This snail has a radulaRadula
The radula is an anatomical structure that is used by molluscs for feeding, sometimes compared rather inaccurately to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food enters the esophagus...
that is specialized, exhibiting overall larger but fewer cones and cusps on the various teeth, which are adapted for grazing on coarser food particles than are eaten by related snails in the subfamily Lithoglyphinae.
Life cycle
Gillia altilis exhibits separate sexes. Sperm is transmitted to the female through a penis that extends from the nape of the male. This species lays its eggs in hemisphere-shaped capsules, singly or in clumps up to six at a time, on leaves and stems of macrophytes (or stones and leaf litter).The egg capsules are ~1.25 mm in diameter.