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ADW: Potamopyrgus antipodarum: INFORMATION
Animal Diversity Web
University of Michigan Museum
of Zoology
Potamopyrgus antipodarum
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By Alexa-Jade Simeron
Geographic Range
Behavior
Habitat
Communication
and Perception
Physical Description
Development
Reproduction
Lifespan/Longevity
Food Habits
Predation
Ecosystem Roles
Economic
Importance for
Humans: Positive
Economic
Importance for
Humans: Negative
Conservation
Status
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References
Geographic Range
New Zealand mudsnails (Potamopyrgus antipodarum) are native
to freshwater streams and lakes of New Zealand and small,
neighboring islands. However, by several speculated means of
human introduction, they have become an invasive species in
Australia, Europe, and North America. Occurrences of the
species in North America, most of which are in the western
United States, have been carefully documented since it was first
discovered in Idaho. The snails are known to be established in
Oregon, California, northern Arizona, New York, and Canada,
affecting major freshwater systems such as Lake Ontario, Lake
Erie, and Lake Superior. They also have been recently introduced in Japan. (Alonso and Castro-Díez, 2008; Benson and Kipp,
2009)
Biogeographic Regions: nearctic ( introduced ) ; palearctic (
introduced ) ; australian ( introduced ) ; oceanic islands ( native )
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Classi cation
Habitat
Kingdom
New Zealand mudsnails prefer to live in streams and the littoral
zones of lakes. They prefer shallow areas but can be found up to
60 m deep. They can be found in aquatic habitats of varying
animals
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Animalia
Class
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substrate types, including silt, sand, gravel, cobble, and macrophyte/vegetation. Densities are highest in macrophyte habitats
and lowest in silt/sand habitats. Individuals of this species live
in both eutrophic and clear waters, but they thrive in disturbed
or degraded waters. New Zealand mudsnails can tolerate a wide
range of temperatures, from near freezing to 34ºC. The optimal
salinity of the water for the snails is near 5%, but they can tolerate brackish waters and even survive salinities as high as 30
to 35% for short periods of time. New Zealand mudsnails prefer
low water velocities but can be found in high velocity areas
buried in the sediment or underneath cobbles and boulders.
("Monitoring the aquatic food base in the Colorado River, Arizona during June and October 2002: Annual report", 2003; Benson and Kipp, 2009; Gustafson, et al., 2004; Richards, 2002)
Gastropoda
Order
Neotaenioglossa
Family
Hydrobiidae
Genus
Potamopyrgus
Species
Potamopyrgus
antipodarum
Habitat Regions: temperate ; freshwater
Aquatic Biomes: lakes and ponds ; rivers and streams ; brackish
water
Other Habitat Features: intertidal or littoral
Range depth
60 (high) m
196.85 (high) ft
Physical Description
New Zealand mudsnails are shelled organisms that are either
gray in color or some shade of light to dark brown. Male and female New Zealand mudsnails are very similar in physical appearance, but females are distinguished from males by the presence of developing embryos in their reproductive systems. In
the western United States, the average length of the shell of the
New Zealand mudsnail is 4 to 5 mm, with a maximum length of
6 to 7 mm. In their native range, the maximum length of the
shell is 12 mm. The surface of the shell is characterized by
right-handed coiling of 5 to 6 whorls demarcated by sulci. The
shells of some individuals have a keel in the middle of each
whorl and/or spines for defense against predators. A terminal
oval aperture covered by a thin operculum is also present. New
Zealand mudsnails may resemble snails native to the United
States, but they are distinguished by their longer, narrower
shells that have a greater number of whorls. (Alonso and Castro-Díez, 2008; Benson and Kipp, 2009; Crosier and Molloy, 2010)
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Other Physical Features: ectothermic ; bilateral symmetry
Sexual Dimorphism: sexes alike
Range length
4 to 12 mm
0.16 to 0.47 in
Development
New Zealand mudsnails are ovoviviparous, meaning that the
development of embryos in their eggs actually occurs within
the female. After completing development, the eggs hatch
within the female, and the female then gives birth to the young
snails. New Zealand mudsnails have been observed to grow 0.1
mm/day at 21ºC under laboratory conditions, with growth rates
depending on the size of the individual. Females reach maturity
at 3 to 6 months of age. (Crosier and Molloy, 2010; Gustafson, et
al., 2004)
Reproduction
New Zealand mudsnails are dioecious. Populations in New
Zealand consist of sexual males and both sexual and asexual females, whereas introduced populations are comprised entirely
of asexual females.
In their native range, individuals that reproduce sexually are
promiscuous. During copulation, the male is found on top of the
shell of a female, and the apertures of the two snails are in contact. Females can either maintain their position and proceed
with mating or move in a manner that displaces the males. The
duration of copulation is typically between 20 minutes and 1.5
hours. Males do not discriminate between sexual females and
asexual or parasitically-castrated females, although their genes
will not be passed to the offspring of the latter two types of females.
Populations found in the United States consist of triploid females that reproduce asexually by way of parthenogenesis. This
type of asexual reproduction is also observed in their native
range and leads to populations of genetically identical females
or clones in both their native and introduced habitats. (Benson
and Kipp, 2009; Crosier and Molloy, 2010; Neiman and Lively,
2004)
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Mating System: polygynandrous (promiscuous)
In New Zealand, reproduction typically occurs every three
months. In the western United Staes, reproduction occurs
throughout the year, with seasonal peaks during the months of
March and October. Females reach sexual maturity at a shell
length of 3 mm and produce approximately 230 young per year.
Larger females produce more offspring than smaller females,
and asexual females produce double the number of female offspring produced by sexual females. This species is ovoviviparous, carrying as many as 10 to 120 eggs at a time for development and giving birth to live snails. Developing embryos are
sometimes present within the reproductive system of asexual
females at the time of birth. (Benson and Kipp, 2009; Crosier
and Molloy, 2010; Gustafson, et al., 2004)
Key Reproductive Features: seasonal breeding ; year-round
breeding ; gonochoric/gonochoristic/dioecious (sexes separate) ;
parthenogenic ; sexual ; asexual ; fertilization ( internal ) ;
ovoviviparous
Breeding interval
In New Zealand,
every 3 months.
Breeding season
Year-round
Average number of
offspring
21.6
Range age at sexual
or reproductive
maturity (female)
3 to 6 months
Range number of
offspring
10 to 120
This author found no published information on parental investment by New Zealand mudsnails.
Although females retain their eggs until they hatch, it's not
known whether the embryos are nourished in anyway other
than via the yolk created when each egg is produced.
Parental Investment: female parental care ; pre-fertilization (
provisioning ) ; pre-hatching/birth ( protecting : female )
Lifespan/Longevity
Under laboratory conditions, marked individuals were observed
to survive over one year. The lifespan of New Zealand mudhttps://animaldiversity.org/accounts/Potamopyrgus_antipodarum/
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snails in natural conditions is unknown. (Gustafson, et al., 2004)
Range lifespan
Status: captivity
1 (high) years
Behavior
New Zealand mudsnails exhibit positive rheotactic behavior -they tend to crawl against the current in flowing water. One authority estimated substrate cruising speed at greater than one
meter per hour, pretty fast for a snail. They also float, alone and
in mats of algae such as Cladophora. During unfavorable environmental conditions, such as dry or cold periods, individuals
of this species are observed to bury into the substrate. (Alonso
and Castro-Díez, 2008; Benson and Kipp, 2009; Gustafson, et al.,
2004)
New Zealand mudsnails are reported to be nocturnal grazers,
although non-brooding females and juveniles foraging more
during the day. It is believed that non-brooding females and juveniles behave in this way that risks predation in order to obtain the necessary energy required for reproduction and
growth, respectively. Infection by trematode parasites of the
genus Microphallus alters the foraging behavior of the snails,
causing them to forage more during the morning hours when
ducks, the predators of New Zealand mudsnails and the final
hosts of Microphallus, are foraging. This change in foraging time
increases the likelihood of parasite transmission. (Benson and
Kipp, 2009; Levri and Lively, 1996)
Key Behaviors: nocturnal ; motile ; sedentary ; solitary
Home Range
Home range sizes for New Zealand mudnails are unknown.
Communication and Perception
Perception in New Zealand mudsnails is mainly via chemical
cues. In their native range, the chemical odor of predatory fish
causes the snails to hide under rocks in an attempt to evade
predation. They are also able to sense light. (Benson and Kipp,
2009)
Perception Channels: visual ; chemical
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Food Habits
New Zealand mudsnails are considered scrapers/grazers. Their
diet consists of diatoms, epiphytic and periphytic algae, and animal and plant detritus. Therefore, they can be considered
planktivores, algivores, and detrivores. (Benson and Kipp, 2009)
Primary Diet: herbivore ( algivore ) ; planktivore ; detritivore
Plant Foods: algae ; phytoplankton
Other Foods: detritus
Predation
Predation on New Zealand mudsnails in North America is unknown. They are known to survive passage through the digestive tracts of some birds and fish, including mountain whitefish
and rainbow trout.
However, in their native range, the snails are consumed by several species of fish and waterfowl and are infected by as many
as 14 parasitic trematodes of the genus Microphallus. Levri and
Lively (1996) observed the foraging behaviors of grey ducks
(Anas superciliosa), mallard ducks (Anas platyrhynchos), black
swans (Cygnus atratus), Canada geese (Branta canadensis), and
scaups (Aythya novaeseelandiae), and they reported that grey
ducks and mallard ducks are the most likely predators of NZMS.
New Zealand mudsnails that experience predation may have
spines on their shells for defense against predators and may
forage less frequently in the presence of predators, especially
during the morning when waterfowl predators are most active.
("Monitoring the aquatic food base in the Colorado River, Arizona during June and October 2002: Annual report", 2003; Benson and Kipp, 2009; Gustafson, et al., 2004; Levri and Lively,
1996)
Known Predators
grey ducks (Anas superciliosa)
mallard ducks (Anas platyrhynchos)
black swans (Cygnus atratus)
Canada geese (Branta canadensis)
New Zealand scaup, aka black teal (Aythya novaeseelandiae)
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Ecosystem Roles
In their freshwater ecosystems, New Zealand mudsnails occupy
the role of scrapers/grazers and are considered to be a link between primary producers and fish. They also play a vital role in
the transmission of Microphallus to ducks by serving as intermediate hosts. ("Monitoring the aquatic food base in the Colorado
River, Arizona during June and October 2002: Annual report",
2003; Gustafson, et al., 2004; Levri and Lively, 1996)
New Zealand mudsnails are known to exist in extremely high
densities and may comprise more than 90% of the macroinvertebrate biomass in introduced habitats. Due to their abundance,
they may out-compete native mollusks and grazers for resources such as food. The decrease in the availability of resources is a likely explanation for the decline in species diversity in the presence of NZMS, the negative correlation between
the NZMS population and that of mayflies, caddisflies, stoneflies, and chironomids, and the listing of five species of mollusks as endangered species. New Zealand mudsnails may also
alter nutrient (carbon and nitrogen) cycling, interrupting energy flow and potentially threatening many other members of
their ecosystems. ("Monitoring the aquatic food base in the Colorado River, Arizona during June and October 2002: Annual report", 2003; Benson and Kipp, 2009; Crosier and Molloy, 2010;
Richards, 2002; Richards, et al., 2010)
Commensal/Parasitic Species
parasitic flatworms in the genus Microphallus
Economic Importance for Humans: Positive
Because New Zealand mudsnails thrive in disturbed and degraded waters, this species can be used as an indicator of
ecosystem status. ("Monitoring the aquatic food base in the Colorado River, Arizona during June and October 2002: Annual report", 2003)
Economic Importance for Humans: Negative
There are no direct, adverse effects of New Zealand mudsnails
on humans, but control of the species is difficult and may be expensive in regions where it is not native. ("Monitoring the
aquatic food base in the Colorado River, Arizona during June
and October 2002: Annual report", 2003; Benson and Kipp, 2009;
Crosier and Molloy, 2010; Richards, 2002; Richards, et al., 2010)
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Conservation Status
New Zealand mudsnails are not a protected species in their native range. Outside the native range, actions are being taken
against the species to limit its spread as a pest. (Richards, et al.,
2010)
IUCN Red List
Not Evaluated
US Federal List
No special status
CITES
No special status
State of Michigan
List
No special status
Other Comments
Several aspects of the ecology of New Zealand mudsnails have
contributed to their success as an invasive species. First, their
tolerance of a wide range of abiotic conditions, such as temperature and salinity, aids them in transport from their native
range via the ballast water of ships. Second, their escape from
natural predators and parasites and their high competitive ability at the early stages of succession contribute to their establishment in introduced habitats. Third, their high fecundity,
fast reproductive rate, and active and passive means of dispersal aid in their spread. Finally, their great abundance allows
them to impact the ecosystem by consuming most of the primary production, dominating nutrient cycles and secondary
production and decreasing populations of other mollusks and
grazers. (Alonso and Castro-Díez, 2008)
The potential and realized negative impacts of New Zealand
mudsnails have been recognized, and measures are being taken
to control their spread based on what is known about their
ecology. New Zealand mudsnails experience mortality when exposed to freezing or high temperatures with low humidity. It is
recommended that all equipment that could be harboring the
snails be frozen for several hours or be exposed to temperatures of 29 to 30ºC and low humidity for a minimum of 24 hours
or temperatures greater than 40ºC and low humidity for a minimum of two hours. (Richards, et al., 2010)
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Contributors
Alexa-Jade Simeron (author), The College of New Jersey, Keith
Pecor (editor), The College of New Jersey, George Hammond
(editor), Animal Diversity Web Staff.
References
United States Geological Survey. Monitoring the aquatic food
base in the Colorado River, Arizona during June and October
2002: Annual report. 02WRAG0028. Flagstaff, AZ: USGS. 2003.
Accessed February 16, 2010 at http://www.esg.montana.
edu/aim/mollusca/nzms/Colorado2002AnnReport.pdf.
Alonso, A., P. Castro-Díez. 2008. What explains the invading success of the aquatic mudsnail Potamopyrgus antipodarum (Hydrobiidae, Mollusca)?. Hydrobiologia, 614 107–116: 107–116.
Benson, A., R. Kipp. 2009. "Potamopyrgus antipodarum" (On-line).
USGS Nonindigenous Aquatic Species. Accessed February 16,
2010 at http://nas.er.usgs.gov/queries/FactSheet.
asp?speciesID=1008.
Crosier, D., D. Molloy. 2010. "New Zealand Mudsnail - Potamopyrgus antipodarum" (On-line pdf). Aquatic Nuisance Species Research Program, U.S. Army Corps of Engineers. Accessed February 16, 2010 at http://el.erdc.usace.army.mil/ansrp/
species_profiles.htm.
Gustafson, D., B. Kerans, C. Cada, D. Richards. 2004. "Biology"
(On-line). New Zealand Mudsnails in the Western USA. Accessed
February 16, 2010 at http://www.esg.montana.edu/aim/
mollusca/nzms/index.html.
Levri, E., C. Lively. 1996. The effects of size, reproductive condition, and parasitism on foraging behaviour in a freshwater
snail, Potamopyrgus antipodarum. Animal Behaviour, 51: 891-901.
Neiman, M., C. Lively. 2004. Male New Zealand mud snails (Potamopyrgus antipodarum) persist in copulating with asexual and
parasitically castrated females. American Midland Naturalist, 154:
88-96.
Richards, D. 2002. The New Zealand mudsnail invades. Aquatic
Nuisance Species Digest, 4: 42-44.
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Richards, D., P. O'Connell, D. Cazier Shinn. 2010. "Simple control
method to limit the spread of New Zealand mudsnail, Potamopyrgus antipodarum" (On-line pdf). Accessed February 16, 2010 at
http://www.esg.montana.edu/aim/mollusca/nzms/
SimpleControl.pdf.
To cite this page: Simeron, A. 2011. "Potamopyrgus antipodarum" (On-line), Animal Diversity Web. Accessed
September 28, 2019 at https://animaldiversity.org/accounts/Potamopyrgus_antipodarum/
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0628151, DUE 0633095, DRL
0918590, and DUE 1122742.
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