Tadpole Physa
The tadpole physa is a native Colorado snail.
About This Species
Because they are so common, the tadpole physa is sometimes called the "pigeon of freshwater" or the "fruit fly of malacology". This group probably represents many species that are named incorrectly because of variations in shell morphology. Also known as: European physa, left-handed pondsnail, acute bladder snail, ashy physa, lateritic physa, pewter physa, tadpole snail, and pewter physa.
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Physical Characteristics
The tadpole physa is medium sized, generally up to 19 mm in length and 14 mm in width. The shell is smooth and egg-shaped with a pointed spire and 4 to 6 whorls. The aperture is large, narrowing at the top, and may display a white rib. The shell is sinistral (left-handed), with a large body whorl, accounting for 75% of the total shell height. Its coloration varies from light yellow to brownish, appearing mottled (black and tan spots and blotches). The body of the tadpole physa is blue-grey with innumerable dark spots.
Habitat
The tadpole physa is found anywhere there is water below 10,500 feet, from drainage ditches and polluted ponds, to swamps and mountain streams. It is considered a "weedy" species, preferring dense aquatic vegetation. The tadpole physa reaches maximum density in warm shallow waters, especially those that are rich, disturbed, and/or artificially eutrophic.
The tadpole physa is common in Colorado. It is believed to be native to North America, but it has been spread to new locations through human activity. The tadpole physa demonstrates rapid maturation, a high reproductive rate, and ability to adapt to poor conditions. After a few weeks of maturation, it has been known to produce 50-100 eggs weekly, for up to 1 year. The tadpole physa is also capable of self-fertilization when isolated. The tadpole physa is now present in: Australia, New Zealand, China, Croatia, Germany, the Netherlands, Czec Republic, Britain, Ireland, and the Mediterranean region. It has been recorded in many localities as a serious pest of economic plants in greenhouses and filtering vegetation in sewage treatment plants.