Radix auricularia
Encyclopedia
Radix auricularia, common name
the big-ear radix, is a species
of medium-sized freshwater snail
, an aquatic
pulmonate gastropod mollusk in the family
Lymnaeidae
.
Radix auricularia is the type species
of the genus Radix.
is thin, roundly ovate and very inflated, such that the last whorl
comprises 90% of its volume.
The shell has a rounded and broad spire
that pinches in steeply at the apex
. The spire short, conic, very small compared with the body whorl.
There are 4–5 whorls
with deep sutures between them. The whorls are convex, inflated, smooth and rapidly increasing. The body whorl is large and spreading. The surface is shining, lines of growth are fine, wavy, crowded, with occasionally a heavy ridge representing a rest period. Sutures are deeply impressed, channeled in some specimens.
The color of the shell is yellow, beige or tan.
The ear-shaped aperture
, which contains no operculum, is around 5 times higher than the spire. The aperture is very large, ovate, occupying four-fifths of the length of the entire shell. It is rounded above and flaring in old specimens below. The peristome is thin and sharp. The columella is sigmoid with a plait across the middle, which is reflected over the umbilicus.
The umbilicus is either wide or covered. Usually the umbilicus is narrow, deep, nearly closed. The epidermis is sometimes marked by light and dark
lines of color, alternating.
The shell of the species can grow to ~30 mm in height and 25 mm in width as a full grown adult. However, most individuals in a population only grow to approximately half the maximum size. The width of the shell is from 12–18 mm, and the height of the shell is 14–24 mm. The shell of Radix auricularia has a width to length ratio greater than 0.75.
is pigmented with a line of dark spots along its edge, irregular spots which show through the shell. The foot is roundly elongated, 18 × 11 mm.
The head is broad, auriculated. This species also has tentacles that are large, flat, lobate, triangular, fan-shaped and wider than they are high.
The blood contains blue hemocyanin
. The heart pulsations are slow and regular: thirty-four per minute. The animal is slow and deliberate in its movements.
For a detailed description of Radix auricularia, including the radula
and reproductive organs, see pages 179-183 in Baker F. C. The Lymnaeidae of North and Middle America, recent and fossil (1911). The Chicago Academy of Sciences.
in Europe:
in Asia:
In the Mid-Atlantic Region it is found in the Charles River
in Massachusetts, Cayuga Lake
and the Hudson River
in New York State, in various ponds in New Jersey
, New York, and Pennsylvania
, and in Lake Champlain
in Vermont.
In the Great Lakes Region: The first record of Radix auricularia in North America is from the Hudson River (which is connected through the New York Canal System to Lakes Erie and Ontario) near Troy, New York
, before 1869. The next record is from Lincoln Park, Chicago
, beside Lake Michigan
in 1901. Subsequently, it was found in Lake Erie
and a tributary stream in 1911 and in 1948, and in Lake Ontario
in 1930. It is also reported from Lake Huron
.
This species has shown a potential to adapt
to new environments within large lakes, as indicated by its recent history in Lake Baikal
, Russia, where this introduced species was previously restricted to shallow bays and floodplain areas, but has recently been able to colonize the rocky drop-off in the lake. The shells of those snails in the new habitat have a more inflated aperture and are more compact than those in the shallow zones, indicating that wave action may have selected for snails with a stronger suctioning foot in the newly colonized habitat.
conditions, but it tends to prefer very lentic waters in lakes, bogs or slow rivers where there is a silt substrate
.
It has been found in environments with a pH
from 6.0–7.1. Its average thermal preference is ~19°C, but there is great fluctuation around this mean, depending on the photoperiod for the time of year. In Great Britain, the species is restricted to hard water. It can tolerate polysaprobic waters, or areas of major pollution and anoxia
with high concentrations of organic matter, sulfide
s and bacteria
.
, Cladophora
spp. (algae), and sand grains.
. It undergoes oogenesis
in spring as the daylight hours increase, and spermatogenesis
in late summer and early fall as the daylight hours decrease. It is iteroparous, breeding biennially. It lays its eggs in clumps of 50 to 150 eggs. Eggs develop faster as temperature increases from 10°C upward, but the eggs fail to survive and develop when the water temperature reaches 36°C.
Radix auricularia serves as a host
to numerous parasites including:
As a host for:
Some of these parasites may infect humans.
One study found that average shell height and infection severity with Trichobilharzia spp. are positively related.
In its native habitat, this species preys on eggs of the parasite Ascaris suum, which survive and develop after passage through the gut
, and are dispersed widely, due to the activity of the snail.
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 big-ear radix, 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 medium-sized 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...
pulmonate gastropod mollusk in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Lymnaeidae
Lymnaeidae
Lymnaeidae is a taxonomic family of small to large air-breathing freshwater snails, aquatic pulmonate gastropod mollusks, that belong to the clade Hygrophila....
.
Radix auricularia is the type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
of the genus Radix.
Forms
Forms of Radix auricularia include:- Radix auricularia f. tumida (Held, 1836)
- Radix auricularia f. subampla (Ehrmann, 1933)
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...
is thin, roundly ovate and very inflated, such that the last whorl
Body whorl
Body whorl is part of the morphology of a coiled gastropod mollusk.- In gastropods :In gastropods, the body whorl, or last whorl, is the most recently-formed and largest whorl of a spiral or helical shell, terminating in the aperture...
comprises 90% of its volume.
The shell has a rounded and broad spire
Spire (mollusc)
A spire is a descriptive term for part of the coiled shell of mollusks. The word is a convenient aid in describing shells, but it does not refer to a very precise part of shell anatomy: the spire consists of all of the whorls except for the body whorl...
that pinches in steeply at the apex
Apex (mollusc)
Apex is an anatomical term for the tip of the mollusc shell of a gastropod, scaphopod, or cephalopod mollusc.-Gastropods:The word "apex" is most often used to mean the tip of the spire of the shell of a gastropod...
. The spire short, conic, very small compared with the body whorl.
There are 4–5 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...
with deep sutures between them. The whorls are convex, inflated, smooth and rapidly increasing. The body whorl is large and spreading. The surface is shining, lines of growth are fine, wavy, crowded, with occasionally a heavy ridge representing a rest period. Sutures are deeply impressed, channeled in some specimens.
The color of the shell is yellow, beige or tan.
The ear-shaped 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....
, which contains no operculum, is around 5 times higher than the spire. The aperture is very large, ovate, occupying four-fifths of the length of the entire shell. It is rounded above and flaring in old specimens below. The peristome is thin and sharp. The columella is sigmoid with a plait across the middle, which is reflected over the umbilicus.
The umbilicus is either wide or covered. Usually the umbilicus is narrow, deep, nearly closed. The epidermis is sometimes marked by light and dark
lines of color, alternating.
The shell of the species can grow to ~30 mm in height and 25 mm in width as a full grown adult. However, most individuals in a population only grow to approximately half the maximum size. The width of the shell is from 12–18 mm, and the height of the shell is 14–24 mm. The shell of Radix auricularia has a width to length ratio greater than 0.75.
Anatomy
The body is flecked with small white spots on the back of the head and tentacles, but not on the foot. 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 pigmented with a line of dark spots along its edge, irregular spots which show through the shell. The foot is roundly elongated, 18 × 11 mm.
The head is broad, auriculated. This species also has tentacles that are large, flat, lobate, triangular, fan-shaped and wider than they are high.
The blood contains blue hemocyanin
Hemocyanin
Hemocyanins are respiratory proteins in the form of metalloproteins containing two copper atoms that reversibly bind a single oxygen molecule . Oxygenation causes a color change between the colorless Cu deoxygenated form and the blue Cu oxygenated form...
. The heart pulsations are slow and regular: thirty-four per minute. The animal is slow and deliberate in its movements.
For a detailed description of Radix auricularia, including 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...
and reproductive organs, see pages 179-183 in Baker F. C. The Lymnaeidae of North and Middle America, recent and fossil (1911). The Chicago Academy of Sciences.
Indigenous distribution
Radix auricularia is native to Europe and Asia.in Europe:
- Croatia
- Czech Republic
- Germany
- British Isles: Great Britain and Ireland
- Netherlands
- Poland
- Slovakia
- and others
in Asia:
- OmanOmanOman , officially called the Sultanate of Oman , is an Arab state in southwest Asia on the southeast coast of the Arabian Peninsula. It is bordered by the United Arab Emirates to the northwest, Saudi Arabia to the west, and Yemen to the southwest. The coast is formed by the Arabian Sea on the...
- and others
Nonindigenous distribution
Radix auricularia is an introduced species in the United States.In the Mid-Atlantic Region it is found in the Charles River
Charles River
The Charles River is an long river that flows in an overall northeasterly direction in eastern Massachusetts, USA. From its source in Hopkinton, the river travels through 22 cities and towns until reaching the Atlantic Ocean at Boston...
in Massachusetts, Cayuga Lake
Cayuga Lake
Cayuga Lake is the longest of central New York's glacial Finger Lakes, and is the second largest in surface area and second largest in volume. It is just under 40 miles long. Its average width is 1.7 miles , and it is at its widest point near Aurora...
and 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 New York State, in various ponds in New Jersey
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...
, New York, and Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
, and in Lake Champlain
Lake Champlain
Lake Champlain is a natural, freshwater lake in North America, located mainly within the borders of the United States but partially situated across the Canada—United States border in the Canadian province of Quebec.The New York portion of the Champlain Valley includes the eastern portions of...
in Vermont.
In the Great Lakes Region: The first record of Radix auricularia in North America is from the Hudson River (which is connected through the New York Canal System to Lakes Erie and Ontario) near Troy, New York
Troy, New York
Troy is a city in the US State of New York and the seat of Rensselaer County. Troy is located on the western edge of Rensselaer County and on the eastern bank of the Hudson River. Troy has close ties to the nearby cities of Albany and Schenectady, forming a region popularly called the Capital...
, before 1869. The next record is from Lincoln Park, Chicago
Lincoln Park, Chicago
Lincoln Park, is one of the 77 community areas on Chicago, Illinois North Side, USA. Named after Lincoln Park, a vast park bordering Lake Michigan, the community area is anchored by the Lincoln Park Zoo and DePaul University...
, beside Lake Michigan
Lake Michigan
Lake Michigan is one of the five Great Lakes of North America and the only one located entirely within the United States. It is the second largest of the Great Lakes by volume and the third largest by surface area, after Lake Superior and Lake Huron...
in 1901. Subsequently, it was found in 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...
and a tributary stream in 1911 and in 1948, and in 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 1930. It is also reported from Lake Huron
Lake Huron
Lake Huron is one of the five Great Lakes of North America. Hydrologically, it comprises the larger portion of Lake Michigan-Huron. It is bounded on the east by the Canadian province of Ontario and on the west by the state of Michigan in the United States...
.
This species has shown a potential to adapt
Adaptation
An adaptation in biology is a trait with a current functional role in the life history of an organism that is maintained and evolved by means of natural selection. An adaptation refers to both the current state of being adapted and to the dynamic evolutionary process that leads to the adaptation....
to new environments within large lakes, as indicated by its recent history in Lake Baikal
Lake Baikal
Lake Baikal is the world's oldest at 30 million years old and deepest lake with an average depth of 744.4 metres.Located in the south of the Russian region of Siberia, between Irkutsk Oblast to the northwest and the Buryat Republic to the southeast, it is the most voluminous freshwater lake in the...
, Russia, where this introduced species was previously restricted to shallow bays and floodplain areas, but has recently been able to colonize the rocky drop-off in the lake. The shells of those snails in the new habitat have a more inflated aperture and are more compact than those in the shallow zones, indicating that wave action may have selected for snails with a stronger suctioning foot in the newly colonized habitat.
Habitat
This species is found in freshwater lakes, ponds, and slow-moving rivers with mud bottoms. Radix auricularia can live on boulders or vegetation in low or high-flow environments, and is capable of tolerating anoxicHypoxia (environmental)
Hypoxia, or oxygen depletion, is a phenomenon that occurs in aquatic environments as dissolved oxygen becomes reduced in concentration to a point where it becomes detrimental to aquatic organisms living in the system...
conditions, but it tends to prefer very lentic waters in lakes, bogs or slow rivers where there is a silt substrate
Substrate (biology)
In biology a substrate is the surface a plant or animal lives upon and grows on. A substrate can include biotic or abiotic materials and animals. For example, encrusting algae that lives on a rock can be substrate for another animal that lives on top of the algae. See also substrate .-External...
.
It has been found in environments with a pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
from 6.0–7.1. Its average thermal preference is ~19°C, but there is great fluctuation around this mean, depending on the photoperiod for the time of year. In Great Britain, the species is restricted to hard water. It can tolerate polysaprobic waters, or areas of major pollution and anoxia
Hypoxia (environmental)
Hypoxia, or oxygen depletion, is a phenomenon that occurs in aquatic environments as dissolved oxygen becomes reduced in concentration to a point where it becomes detrimental to aquatic organisms living in the system...
with high concentrations of organic matter, sulfide
Sulfide
A sulfide is an anion of sulfur in its lowest oxidation state of 2-. Sulfide is also a slightly archaic term for thioethers, a common type of organosulfur compound that are well known for their bad odors.- Properties :...
s and bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
.
Feeding habits
Radix auricularia is in the family Lymnaeidae, which consists of scrapers and collector-gatherers. This species feeds on such items as detritusDetritus
Detritus is a biological term used to describe dead or waste organic material.Detritus may also refer to:* Detritus , a geological term used to describe the particles of rock produced by weathering...
, Cladophora
Cladophora
Cladophora is a genus of reticulated filamentous Ulvophyceae . The genus Cladophora contains many species that are very hard to tell apart and classify, mainly because of the great variation in their appearances, which is affected by habitat, age and environmental conditions...
spp. (algae), and sand grains.
Life cycle
Like almost all pulmonate snails, it is a hermaphroditeHermaphrodite
In biology, a hermaphrodite is an organism that has reproductive organs normally associated with both male and female sexes.Many taxonomic groups of animals do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which both...
. It undergoes oogenesis
Oogenesis
Oogenesis, ovogenesis or oögenesis is the creation of an ovum . It is the female form of gametogenesis. The male equivalent is spermatogenesis...
in spring as the daylight hours increase, and spermatogenesis
Spermatogenesis
Spermatogenesis is the process by which male primary germ cells undergo division, and produce a number of cells termed spermatogonia, from which the primary spermatocytes are derived. Each primary spermatocyte divides into two secondary spermatocytes, and each secondary spermatocyte into two...
in late summer and early fall as the daylight hours decrease. It is iteroparous, breeding biennially. It lays its eggs in clumps of 50 to 150 eggs. Eggs develop faster as temperature increases from 10°C upward, but the eggs fail to survive and develop when the water temperature reaches 36°C.
Parasites
Various lymnaeid snails, including Radix auricularia, are vectors for a diverse range of parasites, particularly trematodes. About 80 % specimens of Radix auricularia from population near Wielkopolska National Park were found to contain trematodes.Radix auricularia serves as a host
Host (biology)
In biology, a host is an organism that harbors a parasite, or a mutual or commensal symbiont, typically providing nourishment and shelter. In botany, a host plant is one that supplies food resources and substrate for certain insects or other fauna...
to numerous parasites including:
- As first and as second intermediate host for:
- Echinostoma revolutumEchinostoma revolutumEchinostoma revolutum is a fluke that can be a parasite in humans. It causes the disease echinostomiasis.- Distribution :Echinostoma revolutum is the most widely distributed species of all 20 Echinostomatidae species and it is found from Asia and Oceania to Europe and the Americas.Echinostomiasis...
- Echinoparyphium recurvatum
- Hypoderaeum conoideumHypoderaeum conoideumHypoderaeum conoideum is a species of digenetic trematode in the family Echinostomatidae.The known first intermediate host of Hypoderaeum conoideum include freshwater snails Planorbarius corneus, Indoplanorbis exustus, Lymnaea stagnalis, Lymnaea limosa, Radix ovata and Radix...
- Echinostoma revolutum
- As first intermediate host for:
- Clinostomum complanatum
- As a second intermediate host for:
- Apatemon gracilis
- As an intermediate host for:
- Radix auricularia is the most important intermediate host for Fasciola giganticaFasciola giganticaFasciola gigantica is a parasitic flatworm of the class Trematoda, which causes tropical fascioliasis. It is regarded as one of the most important single platyhelminth infections of ruminants in Asia and Africa...
. - as an intermediate host for Fasciola hepaticaFasciola hepaticaFasciola hepatica, also known as the common liver fluke or sheep liver fluke, is a parasitic flatworm of the class Trematoda, phylum Platyhelminthes that infects the livers of various mammals, including humans. The disease caused by the fluke is called fascioliasis . F...
in Oman. - Notocotylus attenuatus
- Radix auricularia is the most important intermediate host for Fasciola gigantica
- As a paratenic host for:
- Hymenolepis lanceolata
As a host for:
- Trichobilharzia franki
- Trichobilharzia ocellata
- Trichobilharzia szidati
- Mantoscyphidia radixi
- Orientobilharzia turkestanica
- Diplostomum spathaceum
- Paryphostomum radiatum
- Opisthioglyphe ranae
- Plagiorchis elegans
- Australapatemon burti
- Hypoderaeum conoideumHypoderaeum conoideumHypoderaeum conoideum is a species of digenetic trematode in the family Echinostomatidae.The known first intermediate host of Hypoderaeum conoideum include freshwater snails Planorbarius corneus, Indoplanorbis exustus, Lymnaea stagnalis, Lymnaea limosa, Radix ovata and Radix...
- Isthmiophora melis
- Notocotylus attenuatus
- Tylodelphis clavata
Some of these parasites may infect humans.
One study found that average shell height and infection severity with Trichobilharzia spp. are positively related.
In its native habitat, this species preys on eggs of the parasite Ascaris suum, which survive and develop after passage through the gut
Gut (zoology)
In zoology, the gut, also known as the alimentary canal or alimentary tract, is a tube by which bilaterian animals transfer food to the digestion organs. In large bilaterians the gut generally also has an exit, the anus, by which the animal disposes of solid wastes...
, and are dispersed widely, due to the activity of the snail.
Further reading
- Pfenninger M., Cordellier M. & Streit B. (2006) "Comparing the efficacy of morphologic and DNA-based taxonomy in the freshwater gastropod genus Radix (Basommatophora, Pulmonata)". BMC Evolutionary Biology 2006, 6: 100. doi:10.1186/1471-2148-6-100.
- Big-eared radix (Radix auricularia) Toxicity Studies in PAN Pesticides Database