Giant Titicaca Frog

from Wikipedia, the free encyclopedia
Giant Titicaca Frog
Telmatobius culeus.jpg

Giant Titicaca Frog ( Telmatobius culeus )

Systematics
without rank: Amphibians (Lissamphibia)
Order : Frog (anura)
Subordination : Neobatrachia
Family : Telmatobiidae
Genre : Telmatobius
Type : Giant Titicaca Frog
Scientific name
Telmatobius culeus
( Garman , 1876)

The telmatobius culeus ( Telmatobius culeus ), also called Titicacafrosch or Titicacaseefrosch referred to belongs to the genus of the Andean leptodactylidae ( Telmatobius ). It lives endemically only in Lake Titicaca on the high plateau of the Andes in Peru and Bolivia and is threatened with extinction. This species mainly uses its skin for gas exchange. The heavily folded skin increases the respiratory surface.

features

After Jacques-Yves Cousteau had explored Lake Titicaca in 1973 with divers and diving boats, he reported specimens of this aquatic frog that were said to have been up to 50 cm long and 1 kg in weight. Apparently, this biometric information is based on the sum of the head-trunk length and the outstretched hind legs - a measurement method that is not common in zoology. The maximum head-torso length itself, derived from this information, should be more than 20 cm. Other authors even speak of about 12 inches or less than a foot , which is about 30 centimeters. The Titicaca giant frog is one of the largest species among the frogs, even if it does not reach the size of the West African goliath frog .

Its strongly folded skin is characteristic of the species. It looks like it is way too big for the frog's body. These baggy folds are very noticeable on the back and stomach, but also on the legs. The folds above the neck give the frog the appearance of wearing a monk's robe. The color of the skin is variable and ranges from olive green with a peach-colored belly to gray with black speckles on the back to black with white marbling. Some specimens are colored completely black.

Like all Andean whistling frogs, the giant Titicaca frog has strong hind legs and feet with particularly large webbed feet , which enable it to move quickly underwater.

Way of life in Lake Titicaca

In Lake Titicaca seen here by the Bolivian side, is Telmatobius culeus endemic

Lake Titicaca lies at an altitude of 3810 m on the Altiplano , a plateau of the Andes. It covers an area of ​​8,288 square kilometers and has a maximum depth of 280 m. At this altitude, temperatures below freezing point can occur at night, while intense sunlight with a high ultraviolet component prevails during the day . These ecological conditions have led to the evolution of living things that only occur here. Conversely, changes in environmental factors make these organisms more threatened with extinction than less specialized animals.

For the giant Titicaca frogs, the low air pressure at this altitude was an adaptation factor, as they have to cope with a lower oxygen concentration in water and on land. In order not to expose themselves to the extreme temperature fluctuations on land and the high UV light intensity, the animals have switched to a fully aquatic way of life. The dark to black color on the back of the frogs, which is caused by melanophores in the skin, prevents UV radiation from penetrating - just like the black skin of polar bears .

The giant Titicaca frog takes in oxygen from the water almost exclusively through the skin; this is known as skin respiration . The lungs have been greatly reduced in the course of development. Instead, a greatly enlarged skin surface is formed by a large number of folds and pockets, which give the frog a very flabby and wrinkled appearance. The ratio of the respiratory surface to the volume of the animal is thereby improved. A movement that is similar to the push-up in sports causes the water to be moved past the wrinkles and the gas exchange works better. There are also special adaptations in the blood of these frogs. Their blood has the smallest red blood cells ( erythrocytes ) of all amphibians and at the same time the highest percentage of hemoglobin . The oxygen is coupled to this hemoglobin for further transport through the bloodstream.

When it comes to food, the species is not fussy and feeds on worms, amphipods of the genus Hyalella , water snails, tadpoles and small fish, for example the Ispi Andean parrot Orestias ispi . The prey is swallowed in one piece, with the help of the front legs if necessary.

Danger

During his dives in the early 1970s, Jacques-Yves Cousteau saw the bottom still thickly covered with the giant Titicaca frogs. He spoke of millions of individuals who would have to live here. Today the frog has almost completely disappeared from many parts of the lake. There is no definitive explanation for this decline in populations. Some researchers suspect that the giant titicaca frog has withdrawn to other parts of the lake where there is more food for it. The reduced frog populations are evidently associated with the decline of a small species of fish from the Andean pygmy genus , which is called Ispi in the Quechua language . This fish, which grows to a good 7 cm, is the main source of food for the giant titicaca frog. He may have followed the schools of fish migrating to other areas of the lake.

On the other hand, large quantities of the smaller fish are taken from the lake in order to process them as food for the breeding of larger fish. The giant titicaca frog is also often found in fishermen's nets as bycatch . It is eaten by the indigenous people who live on the shores of the lake and traditionally used as a medicine, but the frog legs are also available in restaurants in Peru and Bolivia. An extract from the frogs is sold as an aphrodisiac under the name “Viagra peruano” . This and the pollution of the lake have put the titicaca frog at high risk. The IUCN now classifies the species as "critically endangered" (threatened with extinction).

External and internal systematics

The very species-rich family of southern frogs (Leptodactylidae i. W. S.) is now understood as paraphyletic and has therefore been split into several monophyletic groups. For example, species of the genus Telmatobius were placed in a family Ceratophryidae together with the horned frogs ( Ceratophrys ) and five other genera until 2011 .

Former species of the genus Telmatobius are now divided into different taxa , which differ in their distribution, their way of life and their body structure. A group that is widespread in southern South America, especially in Patagonia , which has now been put together under the genus Atelognathus , includes rather smaller species of 25 to 50 mm in size, some of which also live terrestrially. A northern distribution group, to which the Titicaca frog also belongs, consists of much larger species that live aquatil in high-lying lakes and rivers of the Andes. In addition, other earlier Telmatobius species are placed in numerous other genera and other families of frogs.

The very different color variants of the giant Titicaca frog have led biologists to suspect that up to seven subspecies occur in the lake. According to investigations by the Bolivian researcher Edgar Benavides, who examined the DNA of the various specimens for the first time in 1997 , they all belong to the same species and there is only a large spectrum of different colors (polymorphism). Telmatobius albiventris with four subspecies and Telmatobius crawfordi are reintegrated into the species Telmatobius culeus by some authors . It has been shown that there are differences in body size and adaptations to the special ecological microhabitat , but these do not act as crossing barriers, but lead to gradually different forms and behavioral patterns.

literature

  • E. Benavides, JC Ortiz, JW Sites Jr .: Species Baudaries among the Telmatobius (Anura: Leptodactylidae) of the Lake Titicaca Basin: Allocyme and Morphological Evidence. Herpetologica 58 (1), pp. 31-55, 2002 PDF.
  • Christopher D. Moyes, Patricia M. Schulte: Animal Physiology . Pearson Studies, 2007, ISBN 3-8273-7270-4 .

Individual evidence

  1. ↑ a b Amphibian Information Resource: Telmatobius culeus (Garman, 1875) - Lake Titicaca Frog (website no longer exists)
  2. ↑ a b Pete Oxford: In the Land of Giant Frogs ( Memento of the original from May 2, 2008 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.nwf.org
  3. ↑ science-online: Andean frogs
  4. ↑ Telmatobius culeus in the endangered Red List species the IUCN 2004. Posted by: Javier Icochea, Steffen Reichle, Ignacio De la Riva, Ulrich Sinsch, Jörn Köhler, 2004. Accessed April 24, 2020th
  5. ↑ American Museum of Natural History - Amphibian Species of the World 5.3, an Online Reference
  6. ↑ Amphibia web: Ceratophryidae
  7. ↑ Edgar Benavides: The Telmatobius species complex in Lake Titicaca: applying phylogeographic and coalescent approaches to evolutionary studies of highly polymorphic Andean frogs. Monografías de Herpetología, 7, pp. 167-185, 2005
  8. Jump up ↑ E. Benavides, JC Ortiz, JW Sites Jr .: Species Boundaries among the Telmatobius (Anura: Leptodactylidae) of the Lake Titicaca Basin: Allocyme and Morphological Evidence. Herpetologica 58 (1), pp. 31-55, 2002 PDF.

Web links