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Freshwater Snails

Island Apple Snail
, Pomacea insularum (
d'Orbigny 1837). 


 Size: 70-80mm diameter, 80mm tall (shell).

 Origin: Uruguay, Argentina

 Distribution: Texas, Georgia, Florida

 Confirmed Location(s): Barker-Cypress Reservoir 

 Habitat: Retention ponds, lakes, reservoirs

 Description The shell is rounded with a small apex. Large specimens are about the size of a baseball. The shell is usually green with dark stripes, and is often found with a thick coating of algae. It has an operculum. The body has two tentacles, a long pair of antennae, and a siphon. It lays pink eggs.

Distinguishing Features: Perforate, not reflected, operculate.

Learn more about Pomacea insularum   

Giant Ramshorn Snail
, Marisa cornuarietis (Linnaeus, 1758). 


 Size: 25-50mm diameter, 10-15mm tall (shell).

 Origin: Columbia, Central & South America

 Distribution: North & South America

 Confirmed Location(s): San Marcos River, Manvel  

 Habitat: Rivers, ponds, creeks

 Description The shell is circular and shaped like a blood cell (the outermost whorl being largest, the smaller whorls sinking into the center like a crater). The shell is green or yellowish-brown, with dark green or brown bands. It can have a very dark periostracum.

Distinguishing Features: Not reflected, operculate.


Genus:  Physella


 Size: 5-10mm tall

 Origin: unknown

 Distribution: unknown

 Confirmed Location(s): Houston, Manvel

 Habitat: Retention ponds, drainage ditches, creeks, reservoirs

 Description The shell is uniformly sinistral, with the aperture on the left side. It is usually a dark brown color, and the surface is quite smooth.

 Distinguishing Features: Sinistral, imperforate, not reflected

This snail can adjust its buoyancy and float on the surface of the water. Underwater, it can be extremely fast...for a snail, that is.


Red-Rim Melania
, Melanoides tuberculatus (
Müller, 1774). 


 Size: 20-30mm tall (shell).

 Origin: Malaysia

 Distribution: Worldwide

 Confirmed Location(s): drainage ditch in Harris County 

 Habitat: creeks, ponds, etc.

 Description The shell is tall and auger-shaped, having about 9 whorls. The color is grayish-brown, with flecks of red or chestnut color. The apex is generally bleached white. The body is a ruddy color and has an operculum.

 Distinguishing Features: Perforate, not reflected, operculate. 

This snail travels from place to place on aquatic plants that are exported through the aquarium trade.

For a complete list of freshwater snails of houston, click here.

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