Information Last Reviewed Spring 2007
This mollusk was first introduced to the United States for use in aquaria by hobbyists. The reason for its popularity is its ability to thrive in freshwater as well as estuarine waters. The most significant impact is M. tuberculata’s role as a transmission vector for several trematodes, which are harmful to humans, and have had an impact on endangered fishes in Texas. This mollusk is also known to competitively exclude native snails.
Melanoides tuberculata shells.
Images modified from: http://shell.kwansei.ac.jp/~shell/pic_book/index.html
Shelled embryos in brood pouch were between 0.07 mm and 2.33 mm in length
Young have up to six shell whorls while in brood pouch
Light brown shell color
Shell has many reddish-brown spots and "flames"
Shell body grooves are rounded with spiral grooves
Prominent vertical ribs on middle and upper whorls of shell
Commonly reaches a length of 30-36 mm
Individuals as large as 80 mm were captured from Las Moras Creek in Texas
Length is at least twice as long as the width
Height of shell opening is always less than half the height of the shell
Several morphs with slightly different characteristics exist ,
Most often confused with Tarebia granifera
Distinguished from Tarebia granifera by presence of rusty colored spots
Base of last whirl is smooth with no prominent ridges
Prominent nodes commonly found on Tarebia granifera are absent on the shell of Melanoides tuberculata
Height of the shell opening of Tarebia granifera is more than half the height of the total shell
Small snail with the ability to colonize habitats and survive for long periods
High juvenile survival rates and long generation times
Able to maintain high population densities
Juveniles use egg yolk and reserves while in the brood pouch
Young are believed to cannibalize other eggs and young while in the brood pouch
Diet consists of fine detritus, algae, and decaying plants ,
Slow growth rates when compared to other Thiarid snails
Slower to reach maturity than other Thiarid snails
Maturity is usually reached at ~25 mm
Parthenogenetic; females reproduce individually without males
Females are ovoviviparous; the eggs hatch inside of the mother and the newborn young continue to grow in brood pouch with nourishment coming from the egg yolk ,
Eggs are 60–90 ìm in diameter
Brood pouch of adult female snails contains young in various stages of development
Brood pouches have been found to hold up to 71 embryos per individual
Juveniles usually reach a length of about 5 mm before leaving female
Most often found in rivers and streams
Prefers slow moving or stagnant water
Not able to tolerate strong currents
Confined to stream banks when strong currents are present
Prefers river banks and edge habitats of river beds ,
Not able to resist dislodgement as well as similar species (Tarebia granifera)
Usually found at temperatures of 18–25 deg C in the US
Minimum temperature for survival is 18 deg C
Maximum temperature for survival is 32.6 deg C
Not able to tolerate high pH levels, which may break down their shell
Little toleration to low levels of oxygen saturation ,
Not found at saturation levels 47% or lower
Not able to stand high salinity levels
Most commonly found in areas with salinity levels lower than 3.3 dS/m
Known to thrive in areas of highest human activity
Middle East and eastern Africa
Established exotic populations are present in most of the tropics, North America, South America, and French Polynesia
North American Distribution
California, Florida, Louisiana, Texas ,,
Means of Introduction
Probably first released from tropical aquaria
Introduced in some areas as a competitor of the native snail Biomphalaria glabrata, which is a host of a parasitic blood fluke (Schistosoma mansoni) ,
First established wild population in the United States was documented in 1964
Outcompetes native snail populations
Known to cause many local extinctions of native snails including primarily Biomphalaria
Intermediate host for the parasitic human lung fluke (Paragonimus westermani)
Reduces the number of parasitic blood fluke (Schistosoma mansoni) snail hosts present in the community
Believed to be an irreversible process, with no known control methods
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