Ribeiroia
Scientific classification
Kingdom:	Animalia
Subkingdom:	Eumetazoa
(unranked):	Bilateria
Superphylum:	Platyzoa
Phylum:	Platyhelminthes
Class:	Trematoda
Subclass:	Digenea
Order:	Echinostomida
Suborder:	Echinostomata
Family:	Psilostomatidae
Genus:	Ribeiroia Travassos, 1939
Species
Ribeiroia congolensis Ribeiroia marini Ribeiroia ondatrae

Ribeiroia is a genus of parasite in the class Trematoda, phylum Platyhelminthes. Three species of Ribeiroia are currently recognized: R. ondatrae in the Americas; R. marini in the Caribbean; and R. congolensis in Africa. This parasite can harm numerous animal species including implication of deformities in certain amphibians, sometimes with synergistic involvement with some pesticides.^[1]

Contents 1 Life cycle 2 Laboratory observations 3 Line notes 4 Bibliography 5 External links

[edit] Life cycle

The adult form lives in the intestines of more than 40 species of birds and at least several species of mammals. Its eggs pass out in its host's faeces, and hatch into miracidia if the faeces fall into water.

The miracidium swims about until it finds a freshwater snail of the family Planorbidae. In the snail the miracidium develops into a redia which produces cercariae. As an example the intermediate host of genus Planorbella provide such an environment before the cercariae exit and attack the amphibian species Rough-skinned Newt, Taricha granulosa.^[2] The cercariae exit from the snail and penetrate the developing limb buds of a metamorphosing frog tadpole, usually the hind limb buds, and encyst there as metacercariae. As a result the affected limbs can develop wrongly, leading to various malformations such as extra limbs, missing limbs, skin webbings, and bony triangles.^[3][4]

[edit] Laboratory observations

In laboratory experiments, Ribeiroia also causes elevated mortality (up to 60%) in developing amphibian larvae. Malformed frogs may survive and mature, but the deformity makes the frog slower, and more easily caught by the parasite's definitive host (birds or mammals), whose gut digests the frog, releasing the parasite, which grows to adulthood in the predator's gut.^[3]

[edit] Line notes

[edit] Bibliography

• P.T.J. Johnson, K. B. Lunde, E. G. Ritchie, and A. E. Launer (1999) The Effect of Trematode Infection on Amphibian Limb Development and Survivorship, Science 284:802-804

[edit] External links

• http://www.blackwell-synergy.com/links/doi/10.1111%2Fj.1523-1739.2003.00217.x
• http://info.hartwick.edu/biology/def_frogs/

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