The World’s Departments
Apple Snail (GAS)
This species has been nominated as among 100 of the
Worst" invaders( #73).
Based on its large distribution in many countries, it
earns the designation of being “of highest priority” because of its
potential to destroy crops and harm people.
canaliculata (Lamarck, 1822)
May Be On the loose and should be considered extremely
dangerous if not a native species!
form: mollusc (mollusk) behavior- amphibious
to be on the lookout!
Added June 25, 2008:
" You can now add Georgia
and South Carolina to the list of US states where channeled apple
snails have been introduced into the wild. I'm an invasive species
biologist for the SC Department of Natural Resources, and we are
now dealing with an infestation in several water bodies just on
the edge of the Waccamaw National Wildlife Refuge near Myrtle
Beach. As a matter of interest, you might like to know recent
genetic work by researchers in Florida and the Philippines have
determined that the species now introduced in FL, TX, GA, and
SC are the island apple snail, Pomacea insularum, rather than
the very similar golden apple snail, P. canaliculata...."
snails naturally live in quiet rivers, ponds, swamps & wetlands.
However, they also survive quite well in reservoirs, lagoons,
drainage canals, paddy fields as well as any other irrigated agricultural
areas and man-made lakes or water courses.
temperate Argentina northwards to the Amazon basin.
range: Most of southern, eastern and south-east Asia, including
the Philippines, Japan, Taiwan, Vietnam, Cambodia, Thailand, Laos,
Korea, Sri Lanka, parts of Indonesia and Malaysia, southern China,
Singapore; also Hawaii, Guam, and Papua New Guinea; the Dominican
Republic; the USA (Florida, Texas, California, Georgia and South
Carolina - recent genetic work by researchers in Florida and the
Philippines have determined that the species now introduced in
FL, TX, GA, and SC are the island apple snail, Pomacea insularum,
rather than the very similar golden apple snail, P. canaliculata.
). Apple Snails can even survive harsh environmental conditions
such as pollutants in the water or low oxygen levels.
canaliculata is widely distributed in lakes, ponds and swamps
throughout its native range of the Amazon Interior Basin and the
Plata Basin. This amphibious animal remains submerged during the
day, hidden in vegetation near the surface. It is more active
during the night when it leaves the water in search for fresh
vegetation. The activity rate of this snail varies highly with
the water temperature. At 18°C they hardly move around, this
in contrast with higher temperatures e.g. 25°C. Nevertheless,
Pomacea canaliculata is more resistant to lower temperatures than
most other snails from the genus Pomacea (The Apple Snail Website,
1998-2003). Quote: ISSG
- apple snail
(English), channeled apple snail, Gold variant apple snail (English),
Gelbe Apfelschnecke (German), golden apple snail (English), golden
kuhol (English-Philippines), miracle snail (English-Philippines)
- In the pet
trade, they are referred to as Canas or mystery snails (Often, pet
shops sell the dark colored Canas as mystery snails and the gold Canas
as Golden Inca snails. (They are some of the largest of all Apple
Snail species you will likely find in the pet store or fish store.
with Pomacea haustrum (from Thompson, 1997).
The shell of this apple snail species is globose and relatively heavy
(especially in older snails). The 5 to 6 whorls are separated by a
deep, indented suture (hence the name 'canaliculata' or 'channeled').
The shell opening (aperture) is large and oval to round. Males are
known to have a rounder aperture than females. The umbilicus is large
size of these snails varies from 40 to 60mm (approx 1.5 to 2.5 inches)
wide and 45 to 75 mm(approx. 1.75 - 3 inches) high depending on the
The colour varies completely yellow and green (cultivated forms) to
brown with or without dark spiral bands (wild form). The shell growth
of this species occurs mainly in spring and summer, while it stagnates
in fall and winter,
The operculum is moderately thick and corneous. The structure is concentric
with the nucleus near the centre of the shell. The colour varies light
(in young snails) to dark brown. The operculum can be retracted in
the aperture (shell opening).
body: The colour of the body varies from
yellow (cultivated), brown to nearly black, with yellow spots on the
siphon, but not as much on the mouth as in Pomacea bridgesii. When
at rest, the tentacles are curled under the shell.
Apple snails, sexes are separate. The females lay clusters of bright
pink eggs attached to solid surfaces (rocks, walls, logs, emergent vegetation,
trash) up to usually about 50 cm above the water surface. Eggs generally
hatch within 7-15 days, but may take longer, probably depending on ambient
mate for 3-4 hours anytime of the day among crowded plants where there
is continuous water supply throughout the year. Reproductive
output can be enormous. Clutch size is up to 1000, but average probably
closer to 200-300 (1000-1200
eggs in a month). These massive clutches
are laid every few weeks. Hatchlings
are voracious feeders, grow quickly (maturing at about 2 months of age).
the first indication that there are applesnails around, may be these
large patches of pink eggs.
and mature fast. Longevity is up to 4 years. Reproductive maturity is
reached in 3 months to 2 years, depending on ambient temperature regime.
highly generalist and voracious macrophytophagous herbivores (leaf eaters)
. Most plants are eaten, however, they prefer young, soft plants. (preferenses
include: rice seedlings, taro, duck weed, water hyacinth, algae, azolla,
and other succulent leafy plants). They also eat decomposing organic
They may, on
occasion, feed on the eggs and juveniles of other snails. They will
also eat decomposing matter.
As pets, they
can also be fed with fish food. Remember, as voracious plant eaters,
they aren't suited for planted aquariums.
are amphibious animals. They stay submerged during the day, hidden in
the vegetation near the border and the surface. They are more active
during the night, also leaves the water in search for fresh vegetation.
The activity rate of this snail varies highly with the water temperature.
Below 18°C they hardly move around, this in contrast with higher
temperatures (25°C). Nevertheless, Pomacea canaliculata is more
resistant to lower temperatures than most other snails from the genus
A freshwater snail with a voracious appetite for water plants including
lotus, water chestnut, taro, and rice.
This species was misguidedly introduced into many Asian countries as
a potential food industry. However, very few people liked the tasteof
it and it quickly became one of the most important pests of rice in
the world. Ppopulations of apple snails can grow rapidly and it is difficult
to control them due to their ability to withstand dry conditions in
In the Philippines alone, over half (1.2 to 1.6 million hectares) of
rice fields are infested with the golden apple snail. The damage and
economic loss have been devastating. Snails consume the base of rice
seedlings and feed on new transplants. The costs of controlling the
snail, replanting, and rice yield loss all account for economic loss
Beyond these costs on such cops as rice, there are the costs associated
with damaging the ecosystem. Snails destroy plants and affect the food
web. They may easily out-compete native species. They have helped in
the decline of native Pila apple snails in south-east Asia.
Human health threats are also associated with this species. It may be
a vector for disease and parasites such as the lungworm, which may cause
the fatal eosinophilic meningoencephalitis disease in humans. Snails
also contribute to skin irritations by being intermediate hosts to the
associated trematodes. Pesticide side-effects include blurring vision
and blindness, skin problems, and loss of nails
Did It get Introduced to Foreign Habitats:
trade: Developed as a domestic aquarium snail and sold in pet stores.
Live food trade: Imported legally and illegally for development of aquaculture
projects for human food.
Nursery trade: Possibly introduced as eggs or small juveniles attached
to aquatic plants.
Smuggling: Illegally introduced, usually for development as a human
Aquaculture (local): Deliberately moved in order to establish new aquaculture
facilities. Probably accidentally dispersed as eggs or more likely small
juveniles on agricultural products. Deliberately introduced to uncontained
wetland systems in the hope of harvesting the snails for food.
Escape from confinement: Escape (or even release) form aquaculture facilities
is probably the major dispersal mechanism.
Release of domestic aquarium snails.
Water currents: Probably one of the main means of dispersal within a
snails may estivate for up to 5 months of the year, meaning that
even with drought conditions or imposed drying, they will likely
survive. Their tolerance to pollution and low oxygen levels is high.
They are able to live on many different types of plant matter, as
well as decomposing organic matter. They have been called “eating
machines” because they can eat 24 hours a day. They have an affinity
for crops such as rice and taro.
- Once an introduced
species to many Asian countries as a food source, today it has no
commercial value as such. However, now it is commonly used and sold
by the pet trade as an aquarium pet.
of established populations is probably not possible. Numerous measures
have been tried in attempts to control apple snails in agricultural
settings. These include:
Several pesticides and molluscicides
have been tried. As well as the costs, they are harmful to other
species, including humans. Long-lasting effects on ecosystems may
not be known for years. No chemicals are currently known to be safe,
effective and cheap enough to use on a large scale, although various
ones are in use, including ones which have been banned in countries
such as Japan, Taiwan and the Philippines.
rice and taro fields, hand picking is a successful method to control
apple snail populations without harming the environment. The disadvantage
is that it only works when done on regular base. The best results
are obtained if the hand picking is done as a community effort.
All visible snails should be collected with a scoop net or by hand.
After collection the snails can be used for human consumption (beware
of parasites!), crushed to serve as a food source for fish or destroyed
otherwise. Eggs should not be forgotten during collection! Baited
traps filled with lettuce, cassava and taro leaves can be used to
attract the snails and to facilitate the collection. All vegetation
and obstacles around fields should be removed as much as possible
as the snails need this to deposit their eggs. When there are no
suitable eggs-laying sites available, the snails are forced to deposit
the eggs on the bare ground where the eggs are very vulnerable and
easily fall into the water, which drowns the eggs. Before draining
a field, make shallow trenches so that the snails will congregate
in the trenches and can be captured easily.
countries have implimented a range of cultural and mechanical control
measures; however, None
of these methods have proven entirely effective, safe, or economically
viable. And, none are likely to be appropriate in natural ecosystems.
good article can be found on AppleSnail.net
Today, scientists taking a differnet approach to this problem and
are studying genetic manipulation to produce snails which reproduce
less. .This may be the best long-term solution though it is still
is not avaialable.
occurring biological control agents: (From AppleSnail.net)
- Red ants
feed on the eggs.
eat the flesh and young snails.
rats bite on the shell and eat the flesh.
of Keeping Golden Apple Snails:
am presently looking into the actual legalities of owning pet apple
snails (cannas, mystery snails). I cannot find that they are actually
illegal to own in any country as a pet. However, owners must take the
initiative to be responsible care-givers. The release of these snails
into nature could be devastating no matter which country they reside
canaliculata (Channeled or Golden Apple Snail) are banned for interstate
movement or import into the United States.
-The entire state
Florida -The entire state
Texas -The entire state
Hawaii -The entire state
North Carolina - The entire state
Other states or territories hereinafter which may be found to be
Contacts For Information:
Be a responsible
pet owner and never release these snails into nature. This way, you
will be part of the solution not the problem and YOU
WILL FEEL GOOD!
Web Sites for more information: