''Pseudis paradoxa'', known as the paradoxical frog or shrinking frog, is a species of hylid frog from South America. Its name refers to the very large—up to long—

tadpole A tadpole or polliwog (also spelled pollywog) is the Larva, larval stage in the biological life cycle of an amphibian. Most tadpoles are fully Aquatic animal, aquatic, though some species of amphibians have tadpoles that are terrestrial animal, ...

(the world's longest), which in turn "shrinks" during

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth transformation or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and different ...

into an ordinary-sized frog, only about a quarter or third of its former length. Although the recordholder was a tadpole in

Amapá Amapá (; ) is one of the 26 federative units of Brazil, states of Brazil. It is in the North Region, Brazil, North Region of Brazil. It is Federative units of Brazil#List, the second-least populous state and the eighteenth-largest state by area ...

that belonged to this species, others in the genus '' Pseudis'' also have large tadpoles and ordinary-sized adults.

Distribution and habitat

The species inhabits ponds, lakes, lagoons and similar waters from the

Amazon Amazon most often refers to: * Amazon River, in South America * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon (company), an American multinational technology company * Amazons, a tribe of female warriors in Greek myth ...

and

the Guianas The Guianas, also spelled Guyanas or Guayanas, are a geographical region in north-eastern South America. Strictly, the term refers to the three Guianas: Guyana, Suriname, and French Guiana, formerly British, Dutch, and French Guiana respectiv ...

, to

Venezuela Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...

and

Trinidad Trinidad is the larger, more populous island of the Republic of Trinidad and Tobago, the country. The island lies off the northeastern coast of Venezuela and sits on the continental shelf of South America. It is the southernmost island in ...

, with a

disjunct distribution In biology, a taxon with a disjunct distribution is one that has two or more groups that are related but considerably separated from each other geographically. The causes are varied and might demonstrate either the expansion or contraction of a s ...

in the Magdalena River watershed in

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

and adjacent far western Venezuela. More southerly populations from the

Pantanal The Pantanal () is a natural region encompassing the world's largest tropical wetland area, and the world's largest Flooded grasslands and savannas, flooded grasslands. It is located mostly within the Brazilian state of Mato Grosso do Sul, but i ...

region to northeastern

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

have been recognized as a subspecies, but are now often considered a full species, '' P. platensis'', although the validity of this split is questionable.

Appearance and behavior

The adult frogs of ''P. paradoxa'' have a snout–to–

vent Vent or vents may refer to: Science and technology Biology *Vent, the cloaca region of an animal *Vent DNA polymerase, a thermostable DNA polymerase Geology *Hydrothermal vent, a fissure in a planet's surface from which geothermally heated water ...

length of and are green to brown coloured with dark green, olive or dark brownish stripes or mottling; the pattern and hue varies significantly. The female of ''P. paradoxa'' lay eggs among water plants; the eggs develop into tadpoles. They always reach a large size, but there are noticeable local variations in the final size of the tadpoles, with those in large temporary waters with plenty of food and few aquatic predators growing larger than those in smaller waters with less food or waters with more aquatic predators. The tadpoles feed mostly on algae. The adult frogs, which are active both day and night and always in or near water, eat insects (such as flies, beetles, true bugs, plantsuckers, butterflies, moths and dragonflies)Franklyn, D. (2015). . The Online Guide to the Animals of Trinidad and Tobago. Retrieved 7 January 2020 and other invertebrates (such as crabs),Franklyn, D. (2015). . The Online Guide to the Animals of Trinidad and Tobago. Retrieved 7 January 2020 and small frogs.Franklyn, D. (2015). . The Online Guide to the Animals of Trinidad and Tobago. Retrieved 7 January 2020 When threatened, the frog uses its strong toes with an extra joint to stir up the muddy bottom and hide. The frog also uses this mechanism to find food on the bottom of lakes and ponds.

Potential use in medicine

In March 2008, scientists working from the Universities of

Ulster Ulster (; or ; or ''Ulster'') is one of the four traditional or historic provinces of Ireland, Irish provinces. It is made up of nine Counties of Ireland, counties: six of these constitute Northern Ireland (a part of the United Kingdom); t ...

and

United Arab Emirates The United Arab Emirates (UAE), or simply the Emirates, is a country in West Asia, in the Middle East, at the eastern end of the Arabian Peninsula. It is a Federal monarchy, federal elective monarchy made up of Emirates of the United Arab E ...

released findings of a study on pseudin-2, a skin compound which protects the paradoxical frog from infection. This work found that a synthetic version of this compound was able to stimulate the secretion of insulin in pancreatic cells under laboratory conditions without

toxicity Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacteria, bacterium, or plant, as well as the effect o ...

to the cells. As such, this synthetic medicine could be used in the treatment of

Type 2 diabetes Type 2 diabetes (T2D), formerly known as adult-onset diabetes, is a form of diabetes mellitus that is characterized by high blood sugar, insulin resistance, and relative lack of insulin. Common symptoms include increased thirst, frequent ...

References

External links

* * {{DEFAULTSORT:Pseudis Paradoxa Amphibians of Bolivia Frogs of Brazil Amphibians of Colombia Amphibians of French Guiana Amphibians of Guyana Frogs of Peru Amphibians of Suriname Amphibians of Trinidad and Tobago Amphibians of Venezuela Amphibians described in 1758 Taxa named by Carl Linnaeus paradoxa