pomacea bridgesii , common names the spike-topped apple snail or mystery snail , is a south american species of freshwater snail with gills and an operculum , an aquatic gastropod mollusk in the family ampullariidae .

pomacea bridgesii

they did not replace the pomacea bridgesii species . pomacea bridgesii had two subspecies .
pomacea bridgesii bridgesii is found in one locality and is considered to be rare ( perera and walls 1996 ) . pomacea bridgesii diffusa is considered to be widespread ( perera and walls 1996 ) .
pomacea bridgesii is known in two varieties in the wild , which could turn out to be two different species . the rare pomacea bridgesii bridgesii subspecies ( reeve , 1856 ) , which is only known from the rio grande , reyes river at beni ( bridges ) and the pomacea bridgesii diffusa subspecies ( blume , 1957 ) , which inhabits almost the entire amazon river system . pomacea bridgesii bridgesii is rather large ( 65mm shell height and more ) , while pomacea bridgesii effusa is much smaller , has a much more pronounced spire and a darker shell colour . the bridgesii snails , available in the aquarium trade are pomacea bridgesii effusa snails and eventually this these snails could turn out to be pomacea effusa instead of a subspecies from pomacea bridgesii .
shell of pomacea bridgesii , view of the inside to illustrate the shell construction .
pomacea bridgesii , subspecies diffusa , . . . - central virginia aquarium support | facebook
pomacea bridgesii , yellow ( golden ) variant . note the flat top of the whorls .
' shell colour genes ' section ( interactive page to learn more about the colour genes in pomacea bridgesii .
i use pomacea bridgesii . that is the term that the usda currently uses , so i go with that .
note : most of the information on this page is pre - 2008 . pomacea bridgesii is now considered a synonym for p . diffusa , although p . bridgesii is still the primary name used here .
ken hayes has replaced the name pomacea bridgesii to pomacea diffusa . as the old name has really stuck to some of us , it is still in use until urltoken
shell and operculum , young snail . note the 90° sutures and flat upper part of the whorls , typical of pomacea bridgesii .
mystery snail - primarily in the domestic aquarium trade , and also often used for pomacea bridgesii , with which p . canaliculata is often confused
blue apple snail ( pomacea bridgesii ) . the shell is in fact white , but the black body of the snail shines through as blue .
yellow - black apple snail ( pomacea bridgesii ) . this colour variant lacks the brown colour of the shell , so the yellow base colour shines through .
watch as the apple snail ( pomacea bridgesii diffusa ) extends his siphon and pumps air into his shell from below the water ' s surface , before taking a nap .
figure 29 . pomacea bridgesii diffusa blume , 1957 . two views of the holotype - zoologische staatssammlung munchen . scale : 1cm . [ photo : r . h . cowie ]
pomacea bridgesi or pomacea bridgesii ? in the original description of this pomacea species , reeve ( conchologica iconica , x , plate 3 . august 1856 ) appearantly intented to name the snail as
the ampullaria from bridges
or
bridges ' s ampullaria
. because species are given a latin name , bridges was seemingly translated to bridgesius prior to conjugation and thus the name became :
ampullaria bridgesii
.
figure 28 . pomacea bridgesii ( reeve , 1856 ) . lectotype - the natural history museum , london . scale : 1 cm . [ photo : r . h . cowie ]
this species is found in paraguay , brazil , and bolivia ( simone 2006 ) . it is most likely that this species occurs in the paraguay and amazon rivers ( g . darrigran pers . comm . 2010 ) . pomacea bridgesii bridgesii : this species is only found in bolivia in the rio grande , reyes river at beni ( pain 1960 , perera and walls 1996 ) . pomacea bridgesii diffusa : this species is very widespread and found throughout the entire amazon river system ( ghesquiere 2007 ) .
shells of introduced and native pomacea collected in florida . apertural and abapertural views of the same specimens : a . pomacea diffusa , b . pomacea haustrum , c . pomacea insularum , d . pomacea paludosa ( the native florida apple snail ) . scale bar : 5 cm .
i use pomacea bridgesii , whether it ' s right or wrong , it ' s used more often and makes things easier . i seem to do the same with a number of species really .
red - yellow variety of pomacea bridgesii . this colour variant lacks the yellow base colour of the shell , so the purple - reddish bands are left without their yellow pigment , which normally makes the brown .
the edible species pomacea canaliculata , originally from south america , was introduced to thailand in 1980 as a food source . further introductions and dispersions elsewhere in the region , including that of the related golden apple snail ( pomacea bridgesii ) , have led to serious devastation of rice crops .
shells of pomacea insularum and pomacea canaliculata collected within the continental u . s . apertural and abapertural views of two specimens of : a . pomacea insularum from lake tohopekaliga , florida ; b . pomacea canaliculata from mecca , california . scale bar : 5 cm .
morphological correspondence between the possible syntype of pomacea haustrum and pomacea specimens collected in palm beach , florida . a . possible syntype of pomacea haustrum ( bmnh 20020660 ) , b . specimen originally identified as pomacea canaliculata collected in 1978 in florida ( flmnh 184660 ) , which we believe to be pomacea haustrum . scale bar : 5 cm .
( of pomacea ( pomacea ) bridgesii ( reeve , 1856 ) ) cowie r . h . & thiengo s . c . ( 2003 ) the apple snails of the americas ( mollusca : gastropoda : ampullariidae : asolene , felipponea , marisa , pomacea , pomella ) : a nomenclatural and type catalog . malacologia 45 ( 1 ) : 41 - 100 . [ details ]
the ' mystery snails ' currently sold by aquarium shops in australia are closely related to golden apple snail , but are not currently considered to be conspecific . they are thought to be a yellow form of pomacea bridgesii ( reeve ) .
jordan p . j . & deaton l . e . 1998 . osmotic regulation and salinity tolerance in the freshwater snail pomacea bridgesii and the freshwater clam lampsilis teres . comparative biochemistry and physiology , 122 ( a ) : 199 - 205 .
wtb : large apple snails in pennsylvania ! looking for pomacea canaliculata and pomacea haustrum . ( they are the ones that get larger than a baseball ! )
pomacea bridgesii bridgesii is a large species , over 65 mm high ( perera and walls 1996 ) . it lays between 200 - 600 pink eggs , which it deposits just above the water line ( ghesquiere 2007 ) . it eats dead and rotting plants and will only consume living plants if there is nothing else to feed on ( ghesquiere 2007 ) . it is usually found burrowed in muddy substrates ( ghesquiere 2007 ) . pomacea bridgesii diffusa is slightly smaller at 40 mm ( perera and walls 1996 ) . this genus is a common neotropical genus , found in low oxygen environments , usually lakes and rivers , where it lays its eggs above the water line ( g . darrigran pers . comm . 2010 ) .
new usgs maps depict ranges of exotic pomacea in the continential u . s .
male at the left inserts his penis in the female ( pomacea diffusa ) .
distinguishing among the various species of pomacea is extremely difficult . the following diagrams illustrate the differences in the channellisation of the suture ( the junction between successive shell whorls ) among the three species of pomacea most likely to be encountered in the aquarium trade : pomacea canaliculata , p . bridgesii , and p . paludosa . these differences are subtle , and given the extensive variation in shell characteristics within species , distinguishing these species requires considerable experience .
note that shell colour , the pattern of darker bands running spirally around the shell and the colour of the animal inside should not in any sense be considered diagnostic of species of pomacea , and cannot be used to distinguish p . b . bridgesii or p . b . diffusa from pomacea canaliculata or other ' golden apple snails ' ( see synomyms ) .
colors : some colors include - - - wild brown , gold , pink , albino , red , chestnut , blue , jade and even shades of purple and burgundy with or without stripes . links to help id the color the color of your snail : colors in pomacea bridgesii
the bright green eggs of pomacea haustrum . ( picture not licenced under creative commons )
vi . you probably have a ' golden apple snail ' - pomacea canaliculata or another of the pomacea species that are included under the umbrella of ' golden apple snail ' .
another photograph of an eye ( pomacea canaliculata ) . ( click on image to enlarge )
scholnick , d . a . , snyder , g . k . & spell , a . r . 1994 . acid - base status of a pulmonate land snail ( helix aspersa ) and a prosobranch amphibious snail ( pomacea bridgesii ) during dormancy . the journal of experimental zoology , 268 : 293 - 298 .
mendoza , r . , aquilera , c . , montemayor , j . & rodriguez , g . 1999 . utilization of artificial diets and effect of protein / energy relationship on growth performance of the apple snail pomacea bridgesii ( prosobranchia : ampullariidae ) . the veliger , 42 ( 2 ) : 101 - 111 . [
reference : cowie , r . h . ( no date ) . the golden apple snail : pomacea species including pomacea canaliculata ( lamarck , 1822 ) ( gastropoda : ampullariidae ) . diagnostic standard .
the eye on the eye stalk of a pomacea canaliculata snail . ( click on image to enlarge )
eye at the base of a tentacle ( pomacea canaliculata ) . ( click on picture for large version )
figure 1 . left : pomacea sp . egg masses on rice plant ( photo : m . halwart ) . right : pomacea canaliculata egg masses on young taro plants ( photo : r . h . cowie )
egg masses are bright pink in colour and a highly characteristic of a small group of exotic pomacea species .
food : fish flake and tablets to feed bottom feeders are eaten by the apple snail . vegetables and fruits high in calcium promotes a healthy shell . here is a link with a list of calcium enriched vegetables that can be used as a guideline care of pomacea bridgesii apple snails snail biscuits are sold on aquabid . com , or make your own ! !
the difficulties of discriminating pomacea insularum from p . canaliculata have been reviewed above . pomacea insularum is reported from argentina , brazil [ 12 ] , and bolivia [ 32 ] and it probably occurs in uruguay and paraguay .
pomacea diffusa was first recorded in florida ( as p . bridgesii ) by clench [ 18 ] . the flmnh has specimens collected in palm beach county in 1967 ( flmnh 20295 ) and miami - dade and broward counties in the early 1970s ( flmnh 22175 , 222247 ) . howells et al . [ 10 ] reported its establishment in mobile , alabama in 2003 .
note the large difference in size and shape between the two snails illustrated above , both of which are adult . the one from the philippines is probably pomacea canaliculata ; the one from cambodia is probably a different species of pomacea .
normally the penis sheat is folded inside the mantle cavity , but sometimes it folded outwards and visible ( pomacea flagellata ) .
figure 16 . egg masses of pomacea canaliculata ( photo : k . a . hayes and r . h . cowie )
according to cowie and thiengo ( 2003 ) , p . scalaris is considered a separate species , but ghesquiere ( 2007 ) considers it to be part of the p . bridgesii complex . cowie et al . ( 2006 ) , however , consider it to be the head of the complex .
clench w . j . ( 1966 ) .
pomacea bridgesi ( reeve ) in florida
. nautilus 79 : 105 .
note that the bright pink egg masses of pomacea canaliculata and other pomacea species are often the first noticeable sign of an infestation . sometimes it may even be difficult to find the snails , although the egg masses are a sure indication of the snails ' presence .
pomacea species are large snails . they range in adult size from ~ 15 mm to about 155 mm ( pomacea maculata ) . those species that fall under the umbrella of the ' golden apple snail ' range in adult size from about 30 mm ( a small p . canaliculata ) to about 90 mm ( undetermined pomacea species observed in south - east asia ) but may reach larger sizes .
kushlan , j . a . ( 1978 ) predation on apple snail eggs ( pomacea ) . the nautilus 92 , 57 - 58 .
mclane , w . a . ( 1939 ) pomacea paludosa a predator on the brown darter . the nautilus 52 , 141 - 142 .
pain , t . ( 1960 ) pomacea ( ampullariidae ) of the amazon river system . journal of conchology 24 , 421 - 432 .
marwoto , r . m . ( 1988 ) the occurrence of a freshwater snail pomacea sp in indonesia . treubia 29 , 275 - 276 .
pain , t . ( 1950a ) a new species of pomacea ( limnopomus ) from venezuela . journal of conchology 23 , 109 - 111 .
the first known ampullariid introduction into the continental u . s . was of marisa cornuarietis , discovered in south florida in 1957 [ 11 ] and probably released through the pet trade . the introduction history of other ampullariids is less clear . pomacea bridgesii was first reported in florida by clench in 1966 [ 18 ] . in 1978 , snails identified as pomacea canaliculata were collected from palm beach county , florida [ 8 ] . since then , apple snails with channeled sutures have been reported in other florida counties , and in alabama , arizona , california , georgia , and texas , with many of these reports since about 2000 .
pain t . ( 1960 ) .
pomacea ( ampullariidae ) of the amazon river system
. journal of conchology 24 : 421 - 432 .
marisa cornuarietis is not selective when it comes to a mating partner and mounts other species as well ( in this case a pomacea flagellata snail ) .
pomacea females lay their eggs out of water . these are usually pigmented , so the photograph may show the eggs of one of these invasive species .
cazzaniga , n . j . ( 1990a ) sexual dimorphism in pomacea canaliculata ( gastropoda : ampullariidae ) . the veliger 33 , 384 - 388 .
these voracious and generalist feeding habits are clearly of great relevance to quarantine implementation . as many pomacea species are difficult to distinguish , and because the feeding habits of many species are poorly known but probably also voracious and generalist , quarantine should err on the side of caution and restrict all species of pomacea , and probably all species of ampullariidae . the suggestion that p . bridgesii is preferentially an algal feeder ( howells , 2002 , 2003 ) has led to its being exempted from such restrictions in certain u . s . regulations , but there is also evidence that it feeds on macrophytic plant material ( raut and aditya , 1999 ) and the exemption may be unjustified .
the synonyms of pomacea canaliculata listed below are taken from the most recent authoritative nomenclatural work on new world ampullariidae ( cowie and thiengo , 2003 ) . some of these synonyms have also been considered synonyms of other pomacea species by some previous authors . most were originally described in the genus ampullaria and many of these have never formally been placed in pomacea , so are listed here as ampullaria . further research may show that some of them are in fact valid species . also , other species have been considered synonyms of pomacea canaliculata by some previous authors but are not listed as such by cowie and thiengo ( 2003 ) .
estebenet , a . l . ( 1995 ) food and feeding in pomacea canaliculata ( gastropoda : ampullariidae ) . the veliger 38 , 277 - 283 .
harper , f . 1936 . the distrubution of the limpkin and its staple food , pomacea . the nautilus , 50 ( 2 ) : 37 - 40 .
mochida osamu . 1991 . spread of freshwater pomacea snails ( pilidae , mollusca ) from argentina to asia . micronesica suppl . , 3 : 51 - 62 .
pain , t . 1960 . pomacea ( ampullariidae ) of the amazon river system . j . conch . , 24 ( 12 ) : 421 - 432 .
mcclary , a . ( 1964 ) surface inspiration and ciliary feeding in pomacea paludosa ( prosobranchia : mesogastropoda : ampullariidae ) . malacologia 2 , 87 - 104 .
perera , g . and yong , m . ( 1990 ) seasonal studies on pomacea paludosa in cuba . florida scientist 53 ( supplement 1 ) , 15 .
the name ' golden apple snail ' refers to more than one species ( cowie and hayes , 2005 ) . one of these species is pomacea canaliculata ( lamarck , 1822 ) and this is probably the most widespread invasive species of pomacea in south - east asia and elsewhere . however , the correct scientific name for the other species ( one or more ) that is also included as ' golden apple snail ' is not known , although one species may be pomacea maculata perry , 1810 .
cazzaniga , n . j . 1990 . sexual dimorphism in pomacea canaliculata ( gastropoda : ampullariidae ) . the veliger , 33 ( 4 ) : 384 - 388 .
figure 9 . pomacea vickeryi pain , 1949 . holotype - the natural history museum , london . scale : 1cm . ( photo : r . h . cowie )
figure 13 . the distinctive egg masses of pomacea canaliculata , laid on the stems of taro plants in hawaii ; each egg mass may contain 200 or more eggs .
mochida , o . ( 1991 ) spread of freshwater pomacea snails ( pilidae , mollusca ) from argentina to asia . micronesica , supplement 3 , 51 - 62 .
pain , t . ( 1950b ) pomacea ( ampullariidae ) of british guiana . proceedings of the malacological society of london 28 , 63 - 74 , 2 pls .
winner , b . e . ( 1989 ) a comparison of three species of pomacea and their spawn . american conchologist 17 ( 3 ) , 15 - 16 .
pain , t . 1963 . the pomacea flagellata complex in central america . j . conch . , 25 ( 5 ) : 224 - 230 , pl . 13 .
sex differences in adult pomacea flagellata flagellata snails . the female is larger and has a straight shell opening , while the male ( left ) has a extended shell lip .
the information displayed on these golden apple snail webpages was sourced from the golden apple snail : pomacea species including pomacea canaliculata ( lamarck , 1822 ) ( gastropoda : ampullariidae ) diagnostic standard and the golden apple snail pest risk review / contingency plan . these documents were kindly provided by office of the chief plant protection officer and plant health australia .
chobchuenchon , w . & bhumiratana , a . 2003 . isolation and characterization of pathogens attacking pomacea canaliculata . world journal of microbiology and biotechnology 19 : 903 - 906 .
kushlan , j . a . ( 1975 ) population changes in the apple snail , pomacea paludosa , in the southern everglades . the nautilus 89 , 21 - 23 .
estebenet , a . l . 1995 . food and feeding in pomacea canaliculata ( mollusca , gastropoda ) . the veliger , 38 ( 4 ) : 277 - 283 . [
mcclary , a . 1962 . surface inspiration and ciliary feeding in pomacea paludosa ( prosobranchia : mesogastropoda : ampullariidae ) . malacologia , 2 ( 1 ) : 87 - 104 .
little , c . ( 1968 ) aestivation and ionic regulation in two species of pomacea ( gastropoda , prosobranchia ) . the journal of experimental biology 48 , 569 - 585 .
bridgesii generally mature at approximately 2 ½ inches in diameter and are characterized by a breathing siphon , 2 sets of tentacles ( 1 located by the mouth and one near the eyes ) and an operculum ( trapdoor ) . they have both a lung and a gill . when the oxygen level in the water drops , you will see them go up to the water surface to inhale fresh air through their siphon .
as with numbers , there are several operations that can be performed on one or more sets . the union of two sets is the set of all elments of the first set , along with all the elements from the second set that are not in the first set ( because there can be no repeated elements ) . for instance , the union of the set s defined above and the set a = { 2 , 4 } is : { 1 , 2 , 3 , 4 , 5 , 7 } . the union operation is important for this model of color trait inheritance in pomacea bridgesii .
snyder , n . f . r . & snyder , h . a . 1971 . defenses of the florida apple snail pomacea paludosa . behaviour , 40 : 175 - 215 .
when snails with a tranlucent shell ( albino pomacea diffusa in this case ) are ready to reproduce , the ovaria of the female ( left ) can become suspicious through the shell .
a number of other identified species of pomacea have also been introduced and are present in the wild , as follows . they may in fact be more widespread than this list indicates .
hanning , g . w . ( 1978 ) oviposition of pomacea paludosa ( say ) in lake okeechobee , florida . bulletin of the american malacological union 1977 , 90 - 91 .
winner , b . e . ( 1996 ) a comparison of four species of pomacea and their spawn . hawaiian shell news 44 ( 7 - 8 ) , 5 - 7 .
thompson [ 8 ] recorded this species ( as p . bridgesii ) in florida in monroe , miami - dade , broward , palm beach , and pinellas counties . the flmnh electronic database also lists samples from alachua county , but records cited from the flmnh database for brevard county [ e . g . [ 10 ] ] ) are in fact from broward county . we have also collected this species in hillsborough and collier counties .
cazzaniga , n . j . 2002 . old species and new concepts in the taxonomy of pomacea ( gastropoda : ampullariidae ) . biocell , 26 ( 1 ) : 71 - 81 .
kushlan , j . a . 1975 . population changes of the apple snail , pomacea paludosa . in the southern everglades . the nautilus , 89 ( 1 ) : 21 - 23 .
cazzaniga , n . j . ( 1990b ) predation of pomacea canaliculata ( ampullariidae ) on adult biomphalaria peregrina ( planorbidae ) . annals of tropical medicine and parasitology 84 , 97 - 100 .
halwart , m . ( 1994 ) the golden apple snail pomacea canaliculata in asian rice farming systems : present impact and future threat . international journal of pest management 40 , 199 - 206 .
diupotex chong m . e . , 1994 . karyological analysis and “g” bands of pomacea flagellata from southeastern mexico . western soc . malac . annu . rep . , 26 : 5 - 7 .
snyder , n . f . r . and snyder , h . a . ( 1971 ) defenses of the florida apple snail pomacea paludosa . behaviour 40 , 175 - 215 , 4 pls .
figure 18 . pomacea sp . , probably p . canaliculata , from a single population in its native range in argentina . scale : 1 cm . [ photo : r . h . cowie ] .
aditya , g . and raut , s . k . ( 2002 ) destruction of indoplanorbis exustus ( planorbidae ) eggs by pomacea bridgesi ( ampullariidae ) . mollusca n research 22 , 87 - 90 .
hanning , g . w . and leedom , w . s . ( 1978 ) schistosome dermatitis from pomacea paludosa ( say ) ( prosobranchia : pilidae ) . the nautilus 92 , 105 - 106 .
litsinger , j . a . and estano , d . b . ( 1993 ) management of the golden apple snail pomacea canaliculata ( lamarck ) in rice . crop protection 12 , 363 - 370 .
thiengo , s . c . ( 1989 ) on pomacea sordida ( swainson , 1823 ) ( prosobranchia , ampullariidae ) . memorias do instituto oswaldo cruz , rio de janeiro 84 , 351 - 355 .
van dinther , j . b . m . ( 1956 ) control of pomacea ( ampullaria ) snails in rice fields . agricultural experiment station , paramaribo , surinam . bulletin 68 , 1 - 20 .
cazzaniga , n . j . 1990 . predation of pomacea canaliculata ( ampullariidae ) on adult biomphalaria peregrina ( planorbidae ) . annals of tropical medicine and parasitology , 48 ( 1 ) : 97 - 100 .
cazzaniga , n . j . & estebenet , a . l . 1990 . a sinistral pomacea canaliculata ( gastropoda : ampullariidae ) . malacological review , 13 ( 1 / 2 ) : 123 - 143 .
halwart , m . 1994 . the golden apple snail pomacea canaliculata in asian rice farming systems : present impact and future threat . international journal of pest management , 40 ( 2 ) : 199 - 206 .
stahlschmidt , v . & wolff , h . g . 1972 . the fine structure of the statocyst of the prosobranch mollusc pomacea paludosa . z . zellforsch , 133 ( 4 ) : 527 - 537 .
estebenet , a . l . and cazzaniga , n . j . ( 1992 ) growth and demography of pomacea canaliculata ( gastropoda : ampullariidae ) under laboratory conditions . malacological review 25 , 1 - 12 .
fujio , y . and von brand , e . ( 1990 ) two linked loci with a null allele for leucine aminopeptidase isozymes in apple snail pomacea canaliculata . nippon suisan gakkaishi 56 , 1039 - 1043 .
howells , r . g . ( 2002 ) comparative feeding of two species of applesnails ( pomacea ) . ellipsaria . the newsletter of the freshwater mollusk conservation society 4 ( 1 ) , 14 - 16 .
lum - kong , a . and kenny , j . s . ( 1989 ) the reproductive biology of the ampullariid snail pomacea urceus ( müller ) . journal of molluscan studies 55 , 53 - 65 .
andrews , e . b . 1965 . the functional anatomy of the gut of the prosobranch gastropod pomacea canaliculata and of some other pilids . proceedings of the malacological society , london , 145 : 19 - 36 .
estebenet , a . l . & cazzaniga , n . j . 1998 . sex - related differential growth in pomacea canaliculata ( gastropoda : ampullariidae ) . journal of molluscian studies , 64 : 119 - 123 .
estebenet , a . l . & pablo r . martin 2002 . pomacea canaliculata ( gastropoda : ampullariidae ) : life - history traits and their plasticity . biocell , 26 ( 1 ) : 83 - 89 .
tsushima , m . , katsuyama m . & matsuno t . 1997 . metabolism of carotenoids in the apple snail , pomacea canaliculata . comp . biochem . physiol . 118b ( 2 ) : 431 - 436 .
estebenet , a . l . and cazzaniga , n . j . ( 1998 ) sex - related differential growth in pomacea canaliculata ( gastropoda : ampullaridae ) . journal of molluscan studies 64 , 119 - 123 .
raut , s . k . and aditya , g . ( 1999 ) occurrence of golden mystery snail pomacea bridgesi ( gastropoda : ampullariidae ) in west bengal , india . current science 77 , 1389 - 1390 .
i ' ve only heard pomacea diffusa ( as a species ) a few times , most notably in papers regarding native snails . until lupin started pushing it recently , i haven ' t heard it in quite awhile .
estebenet , a . l . & cazzaniga , n . j . 1993 . egg variability and the reproductive strategy of pomacea canaliculata ( gastropoda : ampullariidae ) . apex , 8 ( 4 ) : 129 - 133 .
hanning , g . w . & leedom , w . s . 1978 . schistosome dermatitis from pomacea paludosa ( say ) ( prosobranchia : pilidae ) . the nautilus , 92 ( 3 ) : 105 - 106 .
thiengo , s . c . 1989 . on pomacea sordida ( swainson , 1823 ) ( prosobranchia , ampullariidae ) . memorias do instituto oswaldo cruz , rio de janeiro , 84 ( 3 ) : 351 - 355 .
maturation of pomacea paludosa eggs . maturation from freshly laid salmon colored eggs in a thick mucus matrix ( left ) , to the mature pinkish white eggs in calcified shells ( right ) . scale bar : 5 cm .
burky , a . j . ( 1973 ) organic content of eggs and juveniles of an amphibious snail , pomacea urceus ( müller ) , from the venezuelan savannah and their ecological significance . malacological review 6 , 59 .
freiburg , m . w . and hazelwood , d . h . ( 1977 ) oxygen consumption of two amphibious snails : pomacea paludosa and marisa cornuarietis ( prosobranchia : ampullariidae ) . malacologia 16 , 541 - 548 .
guimarães , c . t . ( 1981a ) algumas observações de laboratória sobre biologia e ecologia de pomacea haustrum ( reeve , 1856 ) . memorias do instituto oswaldo cruz , rio de janeiro 76 , 33 - 46 .
okuma , m . , tanaka , k . and sudo , s . ( 1994 ) weed control method using apple snail ( pomacea canaliculata ) in paddy fields . weed research , japan 39 , 114 - 119 .
thompson , f . g . 1997 . pomacea canaliculata ( lamarck 1822 ) ( gastropoda , prosobranchia , pilidae ) : a freshwater snail introduced into florida , u . s . a . malacologial review , 30 : 91 .
turner , r . l . 1996 . use of stems of emergent plants for oviposition by the florida applesnail , pomacea paludosa , and implications for marsh management . florida scientist , 59 ( 1 ) : 34 - 49 .
yusa , y . , 2001 . predation on eggs of the apple snail pomacea canaliculata ( gastropoda : ampullaridae ) by the fire ant solenopsis geminata . journal of molluscian studies , london , 67 : 275 - 279 . [
burky , a . j . ( 1974 ) growth and biomass production of an amphibious snail , pomacea urceus ( müller ) , from the venezuelan savannah . proceedings of the malacological society of london 41 , 127 - 143 .
cazzaniga , n . j . and estebenet , a . l . ( 1988 ) effects of crowding on breeding pomacea canaliculata ( gastropoda : ampullariidae ) . comparative physiology and ecology 13 ( 3 ) : 89 - 96 .
león , r . p . de . ( 1989 ) description of temnocephala haswelli n . sp . ( platyhelminthes ) from the mantle cavity of pomacea canaliculata ( lamarck ) . journal of parasitology 75 , 524 - 526 .
neck . , r . w . ( 1986 ) a second record of an introduced apple snail , pomacea canaliculata , from the lower rio grande valley of texas . texas conchologist 22 ( 3 ) , 54 - 57 .
thiengo , s . c . ( 1987 ) observations on the morphology of pomacea lineata ( spix , 1827 ) ( mollusca , ampullariidae ) . memorias do instituto oswaldo cruz , rio de janeiro 82 , 563 - 570 .
in taiwan , where pomacea was first introduced between 1979 and 1981 , 17 , 000 ha of rice and other crops had been infested by 1982 , increasing rapidly to 171 , 425 ha by 1986 ( mochida , 1991 ) .
figure 17 . pomacea canaliculata ( lamarck , 1822 ) . two views of the lectotype - muséum d ' histoire naturelle de genève . shell height 61 mm ( mermod , 1952 ) . [ photos : y . finet ] .
figure 22 . left - pomacea sp . from cambodia . scale : 1 cm . [ photo : r . h . cowie ] . right - pomacea sp . from texas . note the extremely eroded shell , which is natural . scale : 1 cm . [ photo : r . h . cowie ] . note that both these snails are much larger than the largest p . canaliculata in hawaii ( above ) ; they belong to a different species .
bourne , g . r . and berlin , j . a . ( 1982 ) predicting pomacea dolioides ( reeve ) ( prosobranchia : ampullariidae ) weights from linear measurements of their shells . the veliger 24 , 367 - 370 .
neck , r . w . and schultz , j . g . ( 1992 ) first record of a living channeled applesnail , pomacea canaliculata ( pilidae ) , from texas . texas journal of science 44 , 115 - 116 .
there are a number of large , native australian land snail species . many ampullariids , including pomacea species , are able to survive out of water for considerable lengths of time . this means that one cannot assume that because a snail is out of water it is not an apple snail . however , none of these large native australian land snails possesses an operculum , as do all ampullariidae including species of pomacea ( see the ' plant parts affected ' section ) .
reed , w . l . & janzen f . j . 1999 . natural selection by avian predators on size and colour of freshwater snail ( pomacea flagellata ) . biological journal of linnean society , 67 : 331 - 342 . [
thiengo , s . c . 1987 . observations on the morphology of pomacea lineata ( spix , 1827 ) ( mollusca , ampullariidae ) memorias do instituto oswaldo cruz , rio de janeiro , 82 ( 4 ) : 563 - 570 .
donnay , t . j . and beissinger , s . r . ( 1993 ) apple snail ( pomacea dolioides ) and freshwater crab ( dilocarcinus dentatus ) population fluctuations in the llanos of venezuela . biotropica 25 , 206 - 214 .
howells , r . g . ( 2003 ) pomacea canaliculata : channeled apple snail . releases threaten u . s . agriculture and aquatic environment . aquatic niusance species digest 5 ( 1 ) , 1 , 3 - 5 , 9 .
schnorbach , h . - j . ( 1995 ) the golden apple snail ( pomacea canaliculata lamarck ) , an increasingly important pest in rice , and methods of control with bayluscid . pflanzenschutz - nachrichten bayer 48 , 313 - 346 .
kaneshima , m . , s . yamauchi , and t . kurozumi . ( 1987 ) . effect of rearing temperature and density upon the growth of apple snail , pomacea canaliculata ( lamarck ) . proceedings of the association for plant protection of
lach , l . & cowie , r . h . 1999 . the spread of the introduced freshwater apple snail pomacea canaliculata ( lamarck ) ( gastropoda : ampullariidae ) on o‘ahu , hawai‘i . bishop museum occasional papers 58 : 66 - 71 .
the snail busters blog was created to facilitate communication between aquatic resource managers who are fighting the spread of invasive , south american apple snails , specifically pomacea maculata ( formerly p . insularum ) and p . canaliculata , in the u . s .
guimarães , c . t . ( 1981b ) algumas observações de campo sobre biologia e ecologia de pomacea haustrum ( reeve , 1856 ) ( mollusca , pilidae ) . memorias do instituto oswaldo cruz , rio de janeiro 76 , 343 - 351 .
mochida , o . ( 1988b ) the rice water weevil ( lissorhoptrus oryzophilus kuschel ) and the freswater snail ( pomacea canaliculata ( lamarck ) ) as important pests of crops for plant quarantine in asia . asean planti 1988 , 71 - 80 .
baldia , j . p . & pantastico , j . b . 1991 . enviromental impact of the golden snail ( pomacea sp . ) on rice farming systems in the philippines . wallaceana , no . 65 ( 1991 ) : 14 - 16 .
of the three apple snail species with channeled sutures in the continental u . s . , pomacea canaliculata occurred only in california and arizona , p . insularum occurred in texas , georgia , and florida , and p . haustrum was restricted to florida .
fujio , y . , kurihara , h . and von brand , e . ( 1991a ) differences metric traits among three strains of apple snail , pomacea canalicualta . tohuku journal of agricultural research 41 ( 3 - 4 ) : 61 - 68 .
fujio , y . , von brand , e . and kobayashi , m . ( 1991b ) apparent differential hatchabilities associated with degrees of heterozygosity at leucine aminopeptidase isozyme loci in the apple snail pomacea canaliculata . nippon suisan gakkaishi 57 , 459 - 461 .
leedom , w . s . and short , r . b . ( 1981 ) cercaria pomaceae sp . n . , a dermatitis - producing schistosome cercaria from pomacea paludosa , the florida apple snail . journal of parasitology 67 , 257 - 261 .
our results indicated that : 1 ) south american pomacea were not monophyletic and 2 ) apple snails with channeled sutures were not monophyletic . this latter result is perhaps not surprising . the shells of many pomacea species are similar in overall shape ; unadorned spirally coiled tubes with overlapping whorls that do not depart appreciably from the axis of coiling . given these general constraints , simple changes in the rate of shell whorl expansion and translation down the axis of coiling will affect the degree of overlap of shell whorls , and consequently the degree of channelling of the suture . the degree of channeling may also be affected by changes in the cross - sectional shape of the whorl . convergence in channeled shells is thus not unexpected among the fifty or so species within the genus pomacea .
martin p . r . & estebenet a . l . 2002 . interpopulation variation in life - history traits of pomacea canaliculata ( gastropoda : ampullariidae ) in southwestern buenos aires province , argentina . malacologia , 44 ( 1 ) : 153 - 163 . [
however not all apple snail lay their eggs above the waterline : the snails from the genera asolene , lanistes , marisa and possibly also afropomus and saulea ( anyone info about this ? ) lay their eggs in the water , embedded in a gelatinous mass . these eggs are relatively small when they are laid , but take up a lot of water within the first hours after being laid and thus swell significant . the rate of which the eggs are laid is about 1 every 30 seconds in pomacea canaliculata and pomacea diffusa .
species of pomacea generally lay their eggs above water on the exposed parts of vegetation , rocks , etc . , perhaps to avoid aquatic predators or in response to low oxygen tension in their often near - stagnant aquatic habitats ( snyder and snyder , 1971 ) .
heidenreich , a . , poethke , h . - j . , halwart , m and seitz , a . ( 1997 ) simulation der populationsdynamik von pomacea canaliculata ( prosobranchia ) zur bewertung von managementmaßnahmen . verhandlungen der gesellschaft für ökologie 27 , 441 - 446 .
keawjam , r . s . and upatham , e . s . ( 1990 ) shell morphology , reproductive anatomy and genetic patterns of three species of apple snails of the genus pomacea in thailand . journal of medical and applied malacology 2 , 49 - 62 .
keawjam , r . s . & upatham , e . s . 1990 . shell morphology , reproductive anatomy and genetic patterns of three species of apple snail of the genus pomacea in thailand . med . & appl . malacol . , 2 : 45 - 57 .
egg masses of introduced and native pomacea in the continental u . s . a . p . haustrum , b . p . diffusa , c . p . canaliculata , d . p . paludosa , e . p . insularum . scale bar : 5 cm .
burky , a . j . , pacheco , j . and pereyra , e . ( 1972 ) temperature , water , and respiratory regimes of an amphibious snail , pomacea urceus ( müller ) , from the venezuelan savannah . biological bulletin 143 , 304 - 316 .
albrecht , e . a . & cavicchia , j . c . 2001 . permeability barrier in the mantle epithelium lining the testis in the apple - snail pomacea canaliculata ( gastropoda : ampullariida ) . tissue & cell , 33 ( 2 ) : 148 - 153 . [
lach , l . & cowie , r . h . ( 1999 ) the spread of the introduced freshwater apple snail pomacea canaliculata ( lamarck ) ( gastropoda : ampullariidae ) on o ' ahu , hawai ' i . bishop museum occasional papers 58 : 66 - 71 .
banpavichit , s . , keawjam , r . s . & upatham , e . s . 1994 . sex ratio and susceptibility of the golden apple snail , pomacea canaliculata . the southeast asian journal of trop . med . and public health , 2 : 387 – 391 .
lum - kong , a . ( 1989 ) the potential of pomacea urceus as a culture species in trinidad . in : henderson , i . f . ( ed . ) slugs and snails in world agriculture , british crop protection council monograph 41 , pp 33 - 39 .
cowie r . h & thiengo s . c . ( 2003 ) .
the apple snails of the americas ( mollusca : gastropoda : ampullariidae : asolene , felipponea , marisa , pomacea , pomella ) : a nomenclatural and type catalog
. malacologia 45 : 41 - 100 .
ding , 1798 and pomacea perry 1810 ( mollusca , gastropoda ) : proposed placement on the official list , and ampullariidae gray , 1824 : proposed confirmation as the nomenclaturally valid synonym of pilidae preston , 1915 . bulletin of zoological nomenclature , 54 ( 2 ) : 83 - 88 .
robert h . cowie & silvana c . thiengo . 2003 . the apple snails of the americas ( mollusca : gastropoda : ampullariidae : asolene , felipponea , marisa , pomacea , pomella ) : a nomenclatural and type catalog . malacologia , 45 ( 1 ) : 41 - 100 .
kawano t . , gomes simoes j . l . & correa f . m . a . , 1990 . chromosomes of pomacea sp . ( perry , 1811 ) ( mesogastropoda , mollusca ) . rev . brasil . genet . , 13 ( 4 ) : 675 - 685 .
martin , p . r . , estebenet , a . l . & cazzaniga , n . j . 2001 . factors affecting the distribution of pomacea canaliculata ( gastropoda : ampullariidae ) along its southernmost natural limit . malacologia , 43 ( 1 - 2 ) : 13 - 23 .
macrophyte - feeding species of pomacea , which includes the species subsumed in the category ' golden apple snail ' , are generalist not only in terms of the plant species they will attack ( see hosts ) but also in asmuch as they will feed on most parts of these plants .
turner r . l . & mccabe c . m . 1990 . calcium source for protoconch formation in the florida apple snail , pomacea paludosa ( prosobranchia , pilidae ) – more evidence for physiologic plasticity in the evolution of terrestial eggs . veliger 33 ( 2 ) : 185 - 189 .
location of populations of pomacea insularum in florida . in areas where many populations are in close proximity , a larger circle encompasses the area . localities are based on our own observations / collections and a database compiled by dana denson , florida department of environmental protection , as of june 2006 .
figure 19 . some of the range of shell colour and banding variation , and to some extent shell shape variation , exhibited within a single introduced population of pomacea ( probably p . canaliculata ) from singapore . scale : 1 cm . [ photo : r . h . cowie ] .
albrecht , e . a . , carreño , n . b . and castro - vazquez , a . ( 1996 ) a quantitative study of copulation and spawning in the south american apple - snail , pomacea canaliculata ( prosobranchia : ampullariidae ) . the veliger 39 , 142 - 147 .
cheng , e . y . ( 1989 ) control strategy for the introduced snail pomacea lineata , in rice paddy . in : henderson , i . f . ( ed . ) slugs and snails in world agriculture , british crop protection council monograph 41 , pp . 69 - 75 .
tamaru , c . s . ( 1996 ) control of the apple snail ( pomacea canaliculata ) , planning project . six month report : contract 40785 . unpublished sea grant miscellaneous report . university of hawaii sea grant college program , honolulu , 18 + [ 5 ] + 24 pp .
ruiz , l . j . r . 1988 . estudio morfologico de pomacea flagellata say , 1827 ( gastropoda : ampullaridae ) y algunas consideraciones sobre su taxonomia y distribucion geografica en mexico . anales inst . biol . unam , 58 , ser . zool . , 1 : 21 - 34 .
• the blobs are the egg masses of apple snails from the ampullariidae family . these freshwater animals have large , rounded shells , and are found in many tropical and subtropical areas . for example , the genus pila occurs naturally in africa and malaysia , whereas pomacea is found in the americas .
introduced in 1981 , pomacea had spread to 35 out of 47 prefectures by 1989 ( mochida , 1991 ) . by 1995 it occurred in over 50 , 000 ha of paddy fields ( wada , 1997 ) , and by 2001 in almost 70 , 000 ha ( ichinose , 2005a ) .
cowie , r . h . & thiengo , s . c . 2003 . the apple snails of the americas ( mollusca : gastropoda : ampullariidae : asolene , felipponea , marisa , pomacea , pomella ) : a nomenclatural and type catalog . malacologia 45 ( 1 ) : 41 - 100 .
[ this is a catalog of all the species and genus names used for ampullariids of the new world , which is the source of the invasive species of pomacea , with additional information on synonymies , type localities , location of type material , and a comprehensive bibliography of original taxonomic literature . ]
keawjam , r . s . , poonswad , p . , upatham , e . s . & banpavichit , s . 1993 . natural parasitic infection of the golden apple snail , pomacea canaliculata . the southeast asian journal of trop . med . and public health , 24 : 170 - 177 .
figure 20 . a sample of snails from a single population of pomacea ( probably p . canaliculata ) from the philippines , characteristically covered in part by fine dried mud from the paddy fields from which they were collected . scale : 1 cm . [ photo : r . h . cowie ] .
palis , f . v . , macatula , r . f . and browning , l . ( 1996 ) niclosamide , an effective molluscicide for the golden apple snail ( pomacea canaliculata lamarck ) control in philippine rice production systems . 1996 british crop protection council symposium proceedings 66 , 213 - 230 .
thiengo , s . c . , borda , c . e . and araújo , j . l . b . ( 1993 ) on pomacea canaliculata ( lamarck , 1822 ) ( mollusca ; pilidae : ampullariidae ) . memorias do instituto oswaldo cruz , rio de janeiro 88 , 67 - 71 .
definitive diagnosis of ' golden apple snails ' is not possible at this time , inasmuch as the term ' golden apple snail ' refers to more than one species that have not yet been definitively identified . nevertheless , pomacea canaliculata and a number of other species that probably are part of the ' golden apple snail ' complex are readily distinguished as members of the family ampullariidae , and can be readily distinguished from other genera in the family . ability to distinguish ampullariidae from snails in other snail families should be demonstrated , as should ability to distinguish members of the genus pomacea from other members of the family .
cowie r . h . & thiengo s . c . ( 2003 ) the apple snails of the americas ( mollusca : gastropoda : ampullariidae : asolene , felipponea , marisa , pomacea , pomella ) : a nomenclatural and type catalog . malacologia 45 ( 1 ) : 41 - 100 . [ details ]
albrecht , e . a . & carreno , n . b . & castro - vazquez , a . 1966 . a quantitative study of copulation and spawning in the south american apple - snail , pomacea canaliculata ( prosobranchia : ampullariidae ) . the veliger , 39 ( 2 ) : 142 - 147 .
cowie , r . h . , kabat , a . r . & evenhuis , n . l . 2001 . ampullaria canaliculata lamarck , 1822 ( currently pomacea canaliculata ; mollusca , gastropoda ) : proposed conservation of the specific name . bulletin of zoological nomenclature 58 ( 1 ) : 13 - 18 .
mercado - laczko a . c . & lopretto e . c . 1998 . estudio cromosómico y cariotípico de pomacea canaliculata ( lamarck , 1801 ) ( gastropoda : ampullariidae ) . rev . mus . arg . ciencas nat . “b rivadavia” , hidrobiol . , 8 ( 2 ) : 15 - 20 .
winik , b . c . , catalan , n . m . y . & sclick , o . c . 2000 . genesis of the apyrene parasperm in the apple snail pomacea canaliculata ( gastropoda : ampullariidae ) : an ultrastructural study . journal of molluscian studies , 67 : 81 - 93 . [
viviparids are viviparous ( giving birth directly to small snails ) , the overall shape of the upper shell whorls is rather conical and the aperture is rather round . in contrast , pomacea spp . are oviparous ( laying eggs ) , the shell is generally globular not conical and the aperture is more elongate .
thiengo , s . c . ; borda , c . e . & barros araujo , j . l . 1993 . on pomacea canaliculata ( lamarck , 1822 ) ( mollusca ; pilidae : ampullariidae ) . memorias do instituto oswaldo cruz , rio de janeiro , 88 ( 1 ) : 67 - 71 .
dreon m . , lavarias s . , garin c . f . , heras h . , & pollero r . j . , 2002 . synthesis , distribution , and levels of an egg lipoprotein from the apple snail pomacea canaliculata ( mollusca : gastropoda ) . journal of experimental zoology , 292 : 323–330 . [
estoy , g . f . , y . yusa , t . wada , h . sakurai , and k . tsuchida . ( 2002 ) . size and age at first copulation and spawning of the apple snail , pomacea canaliculata ( gastropoda : ampullariidae ) . applied entomology and zoology 37 , 199 - 205 .
santos , c . a . z . , penteado , c . h . s . and mendes , e . g . ( 1987 ) the respiratory responses of an amphibious snail pomacea lineata ( spix , 1827 ) , to temperature and oxygen tension variations . comparative biochemistry and physiology 86a , 409 - 415 .
gutierrez , a . , perera , g . , yong , m . & fernandez , j . a . 1997 . relationships of the prosobranch snails pomacea paludosa , tarebia gernifera and melanoides tuberculata with the abiotic environment and freshwater snail diversity in the central region of cuba . malacologial review , 30 : 39 - 44 .
acosta , b . o . and pullin , r . s . v . ( 1991 ) environmental impact of the golden snail ( pomacea sp . ) on rice farming systems in the philippines . freshwater aquaculture center , central luzon state university , munoz , nueva ecija ; iclarm , manila , vi + 34 pp .
the history of the introduction of non - native apple snails into south - east asia ( above ) and the damage they cause to rice farming have been reviewed by halwart ( 1994 ) and naylor ( 1996 ) , among others . one or more species of pomacea ( usually identified as pomacea canaliculata ) have become pests of paddy rice in all the asian countries to which they have been introduced , but probably most seriously in the philippines . the following few paragraphs outline the rapid spread of the snails throughout the rice - growing regions of some of the countries infested ; details of the snails ' spread in other countries are not readily available .
albrecht , e . a . & carreno , n . b . & castro - vazquez , a . 1999 . a quantitative study of the environmental factors influencing the seasonal onset of reproductive behaviour in the south american apple snail pomacea canaliculata ( gastropoda : ampullariidae ) . journal of molluscian studies , 65 : 241 - 250 .
pomacea was also introduced to vietnam in 1988 ; by 1997 the total area sustaining damage to rice was 110 , 000 ha ; by 2001 it was 199 , 000 ha ; and in 2003 , 23 , 000 ha were damaged seriously , while 250 , 000 ha suffered medium or light damage ( nguyen , 2005 ) .
diupotex chong m . e . , foster n . & rubio s . a . , 1997 . some chromosomic and electrophoretic characteristics of the genus pomacea ( gastropoda : pilidae ) from southeastern mexico . in joint meeting of the american malacological union and the western society of malacologists . santa barbara , june 22 - 27 . abstracts .
albrecht , e . a . , n . b . carreno , and a . castro - vazques . ( 1999 ) . a quantitative study of environmental factors influencing the seasonal onset of reproductive behaviour in the south american apple - snail pomacea canaliculata ( gastropoda : ampullariidae ) . journal of molluscan studies 65 , 241 - 250 .
wada , t . ( 1997 ) introduction of the apple snail pomacea canaliculata and its impact on rice agriculture . in : proceedings . international workshop on biological invasions of ecosystems by pests and beneficial organisms . national institute of agro - environmental sciences , ministry of agriculture , forestry and fisheries , tsukuba , pp . 170 - 180 .
heidenreich , a . and halwart , m . ( 1995 ) fish farming and other integrated pest management strategies against pomacea snails in rice fields : a computer simulation . in : proceedings of the 4th asian fisheries forum , 16 - 20 october 1995 , beijing , p . r . china . beijing , pp . 1 - 4 .
figure 7 . pomacea insularum ( d ' orbigny , 1835 ) . two syntypes : left - the natural history museum , london ; right - the muséum national d ' histoire naturelle , paris . scale bar : 1 cm . [ photos : r . h . cowie ] . note the intraspecific differences in shall shape between these two syntypes
santoz , c . a . z . , penteado , c . h . s . & menez , e . g . 1987 . the respiratory responses of an amphibious snail pomacea lineata ( spix , 1827 ) , to temperature and oxygen tension variations . compendium of biochemy and physilogy , oxfort , 86a ( 3 ) : 409 - 415 .
the term ' apple snail ' refers to species of the freshwater snail family ampullariidae primarily in the genera pila , which is native to asia and africa , and pomacea , which is native to the new world . they are so called because the shells of many species in these two genera are often large and round and sometimes greenish in colour .
adalla , c . b . and morallo - rejesus , b . ( 1989 ) the golden apple snail , pomacea sp . a serious pest of lowland rice in the philippines . in : henderson , i . f . ( ed . ) slugs and snails in world agriculture , british crop protection council monograph 41 , pp . 417 - 422 .
the apple snail species from the genera pila and pomacea deposit their eggs above the waterline . they are guided to the egg clutch in an ovipositor groove over the snail ' s body . this groove lays on top of a swollen part of the foot , which is formed by inflating the tissue below with fluid . the ovipositor structure is , as result of this , visible as a semi - transparant lump on the snails body . note however , that not all apple snails exhibit such visible structure when depositing their eggs . one of the species which has a good visible ovipositor structure is pomacea diffusa . to get a better idea about the eggs deposition , watch this mpeg movie of a pomacea diffusa snail depositing her eggs : [ egg _ laying _ movie ] ( 267kb ) . note that the speed of the movie has been increased ( 25 times real time ) . the eggs of the species that deposit their eggs above the waterline are soft when they appear from the snails body , but the eggshell hardens within a few hours after they are laid .