Polystoma nearcticum

Geographic Range

Polystoma nearcticum are found in the United States.


The fluke lives in the urinary bladder of its host species, North American treefrogs in the genus Hyla, which breed primarily in ponds in the eastern United States. It also spends a considerable amount of its developmental period in the water. This species can survive in temperatures as low as 0-3 degrees Celsius.

  • Aquatic Biomes
  • lakes and ponds

Physical Description


Polystoma nearcticum go through two stages of development, the bladder generation and the branchial generation. Adult bladder forms of Polystoma nearcticum begin to lay eggs at the same time the host (tree frog) becomes sexually active in the spring, and they are voided with its urine. Development of egg begins in the water. Once the larvae are fully developed, they hatch and enter the gill chambers of tadpoles, where they mature for 22 days. Then the larvae are washed from the gills through the spiracle and into the water. These free swimming larva enter the anus of the frog and head once again to the urinary bladder.

  • Parental Investment
  • no parental involvement


Food Habits

Polystoma nearcticum feeds exclusively on its host organism's blood.

Ecosystem Roles

Species Used as Host
  • North American species of Hyla

Conservation Status

These species are not in danger as far as conservation and biodiversity are concerned.

  • IUCN Red List [Link]
    Not Evaluated


Melissa Kim (author), University of Michigan-Ann Arbor.



living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.


animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature


forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

native range

the area in which the animal is naturally found, the region in which it is endemic.


an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death


Coniferous or boreal forest, located in a band across northern North America, Europe, and Asia. This terrestrial biome also occurs at high elevations. Long, cold winters and short, wet summers. Few species of trees are present; these are primarily conifers that grow in dense stands with little undergrowth. Some deciduous trees also may be present.


that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).


Noble, Kingsly G. 1954. The Biology of the Amphibia Dover Publication Inc. New York. pg. 435 <BR>

Olsen, Wilford O. 1974. Animal Parasites, Their life Cycle and Ecology, Third Edition. University Park Press, pg. 206-209 <BR>

Smyth, J.D. 1962. Introduction to Animal Parasitology. The English Universities Press Ltd. London. pg. 127 <BR>