''Calyptocephalella'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

frog A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order (biology), order Anura (coming from the Ancient Greek , literally 'without tail'). Frog species with rough ski ...

s in the family

Calyptocephalellidae The Calyptocephalellidae are a family of toads (although not true members of the Bufonidae) found in Chile containing two living genera, '' Calyptocephalella'' and '' Telmatobufo.'' The genus ''Calyptocephalella'' contains one living species, ...

. It is represented by a single living species, ''Calyptocephalella gayi'', commonly known as the helmeted water toad, Chilean helmeted bull frog, or wide-mouthed toad. Additionally, there are a few extinct species that are only known from

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

and

Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...

fossil remains from

Patagonia Patagonia () is a geographical region that includes parts of Argentina and Chile at the southern end of South America. The region includes the southern section of the Andes mountain chain with lakes, fjords, temperate rainforests, and glaciers ...

in South America and the

Antarctic Peninsula The Antarctic Peninsula, known as O'Higgins Land in Chile and Tierra de San Martin in Argentina, and originally as Graham Land in the United Kingdom and the Palmer Peninsula in the United States, is the northernmost part of mainland Antarctica. ...

(at times when it was warmer and wetter). The helmeted water toad living today is

aquatic Aquatic means relating to water; living in or near water or taking place in water; does not include groundwater, as "aquatic" implies an environment where plants and animals live. Aquatic(s) may also refer to: * Aquatic animal, either vertebrate ...

to semi-aquatic, and found in deep ponds and reservoirs in central Chile and possibly adjacent west-central Argentina.AmphibiaWeb:
Calyptocephalella gayi.
' Retrieved 21 March 2015. This very large frog typically weighs up to , but sometimes considerably more. It is the world's second largest frog after the

goliath frog The goliath frog (''Conraua goliath''), otherwise known commonly as the giant slippery frog and the goliath bullfrog, is a species of frog in the family Conrauidae. The goliath frog is the largest living frog. Specimens can reach up to about in ...

. It is threatened by capture for human consumption,

habitat loss Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

, pollution,

introduced species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived ther ...

and the disease

chytridiomycosis Chytridiomycosis ( ) is an infectious disease in amphibians, caused by the chytrid fungi '' Batrachochytrium dendrobatidis'' and '' Batrachochytrium salamandrivorans''. Chytridiomycosis has been linked to dramatic population declines or extinc ...

. It is often kept in

herpetoculture Herpetoculture is the keeping of live reptiles and amphibians in captivity, whether as a hobby or as a commercial breeding operation. "Herps" is an informal term for both reptiles and amphibians, shortened from the scientific umbrella term “her ...

, mostly locally where it is farmed for food, but also in other countries as a pet.

Characteristics

The helmeted water toad is a robust species with a broad head and large mouth. It is very large, and can reach 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 up to in males and in females. The typical maximum weight is , but exceptionally large individuals can reach . Such giants are essentially unheard of today, although there are recent records of several individuals weighing . It is the largest

anuran A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order Anura (coming from the Ancient Greek , literally 'without tail'). Frog species with rough skin texture due to ...

(frogs and toads) of the Americas, surpassing other large species like the Blomberg's,

cane Cane or caning may refer to: *Walking stick, or walking cane, a device used primarily to aid walking * Assistive cane, a walking stick used as a mobility aid for better balance * White cane, a mobility or safety device used by blind or visually i ...

Colorado River The Colorado River () is one of the principal rivers (along with the Rio Grande) in the Southwestern United States and in northern Mexico. The river, the List of longest rivers of the United States (by main stem), 5th longest in the United St ...

, cururu and

smooth-sided toad The smooth-sided toad or spotted toad (''Rhaebo guttatus''), formerly known as ''Bufo guttatus'', is a species of toad in the family Bufonidae. It is found in the Amazonian Bolivia, Brazil, Colombia, Ecuador, Peru, and Venezuela, as well as the ...

s, and the American bull-,

Lake Junin Lake Junin (; Spanish language, Spanish ''Lago Junín'', named after the nearby town of Junín, Peru, Junin) or Chinchaycocha (possibly from Quechua language, Quechua ''chincha, chinchay'' north, northern, ''chinchay'' ocelot, ''qucha'' lake, lag ...

mountain chicken ''Leptodactylus fallax'', commonly known as the mountain chicken or giant ditch frog, is a critically endangered species of frog that is native to the Caribbean islands of Dominica and Montserrat. The population declined by at least 80% from 19 ...

and

Titicaca water frog ''Telmatobius culeus'', commonly known as the Titicaca water frog or Lake Titicaca frog, is a medium-large to very large and endangered species of frog in the family Telmatobiidae. It is entirely aquatic and found only in the Lake Titicaca basi ...

s. The maximum snout–to–vent is similar to that of the world's largest frog, the African

(''Conraua goliath''), which however can weigh more. Helmeted water toads are colored yellow, brown and green, with light green in mature specimens, while the oldest are gray, or have gray patches on a dark background. The

olive The olive, botanical name ''Olea europaea'' ("European olive"), is a species of Subtropics, subtropical evergreen tree in the Family (biology), family Oleaceae. Originating in Anatolia, Asia Minor, it is abundant throughout the Mediterranean ...

-brown to dusky tadpoles also grow unusually large, typically exceeding lengths of and reaching up to .

Behavior

Reproduction and aggressive behavior

The helmeted water toad breeds in the South Hemisphere spring (September–October) when males call. The female lays between 1,000 and 16,000 eggs in shallow, well-vegetated water. Although many eggs never hatch, captive studies have shown that a single spawning may result in more than 1,000 tadpoles. Typical larval (tadpole) life lasts five months to a year, but up to two years. After hatching, larval survival depends on the presence of vegetation as the existence of movements in the body of water maintain good oxygenation, but the presence of seasonal ponds with some degree of drainage is essential for hatching, as these sites contain fewer predators to the larvae. Then, the transport of larvae from ponds, to larger bodies of water during the rains, or transport of these among several bodies of water facilitates the survival and allows a good development of populations. The larvae prefer cooler areas of the body of water and protective aquatic vegetation, unlike toad larvae that occupy the same sites and have a higher degree of pigmentation that protects them from the solar rays. While the species is almost entirely aquatic, especially young helmeted water toads that are recently metamorphosed from the tadpole stage often can be seen on land. In captivity, they can breed when 2 years old and a female was able to breed until 24 years old. The helmeted water toad is quite aggressive and it has an aggressive call specifically directed at other individuals of the same species. During encounters with conspecifics they inflate their body, open their large mouth and may jump forward towards an opponent. The same behavior can be directed at potential predators, including humans, although they may choose to escape silently by diving into the water.

Feeding

Their food in the tadpole stage is vegetation and

detritus In biology, detritus ( or ) is organic matter made up of the decomposition, decomposing remains of organisms and plants, and also of feces. Detritus usually hosts communities of microorganisms that colonize and decomposition, decompose (Reminera ...

. Adults feed on virtually any animal they can overpower and swallow, including fish, invertebrates, small birds, small mammals and other frogs.

Cannibalism Cannibalism is the act of consuming another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded in more than 1,500 species. Human cannibalism is also well document ...

also occurs.

Conservation status

The helmeted water toad is a

vulnerable species A vulnerable species is a species which has been Conservation status, categorized by the International Union for Conservation of Nature as being threatened species, threatened with extinction unless the circumstances that are threatened species, ...

according to

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

due to capture for human consumption (to a lesser degree also to supply the pet trade),

, pollution, introduced species (especially

trout Trout (: trout) is a generic common name for numerous species of carnivorous freshwater ray-finned fishes belonging to the genera '' Oncorhynchus'', ''Salmo'' and ''Salvelinus'', all of which are members of the subfamily Salmoninae in the ...

and

African clawed frog The African clawed frog (''Xenopus laevis''), also known as simply xenopus, African clawed toad, African claw-toed frog or the ''platanna'') is a species of African Aquatic animal, aquatic frog of the family Pipidae. Its name is derived from the ...

) and the disease

(caused by '' Batrachochytrium dendrobatidis''). The species is kept in frog farms that supply the food market, but helmeted water toads take three years to reach a marketable size; they have been unable to produce enough to meet the demand and the farms have not been lucrative. Despite being illegal in Chile, wild caught individuals are still frequently sold for food in the country and control is insufficient. International trade require a permit, as the species is listed on

CITES Appendix III CITES (shorter acronym for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of inte ...

. On average, helmeted water toads experience water temperatures of about in the winter and in the summer. While their tolerance is broader, they already have an increased mortality rate at and are entirely unable to cope with temperatures of or warmer. It is projected that a significant percentage of the population will disappear before the year 2100 due to

global warming Present-day climate change includes both global warming—the ongoing increase in global average temperature—and its wider effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes ...

. In some places where water levels have been greatly reduced due to a combination of climate change (drought) and extraction for agriculture, mass deaths of helmeted water toads have already been recorded. It is also threatened by the introduction of the

(known in Chile as the African toad), a species that has affected, as in other parts of the world, local amphibians when carrying the

chytrid fungus Chytridiomycota are a division of zoosporic organisms in the kingdom Fungi, informally known as chytrids. The name is derived from the Ancient Greek ('), meaning "little pot", describing the structure containing unreleased zoospores. Chytrids ...

''Batrachochytrium dendrobatidis'', which passes through the skin of amphibians not adapted to it. Their cells react to the

pathogen In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory of d ...

, causing hardening and, therefore,

hyperkeratosis Hyperkeratosis is thickening of the stratum corneum (the outermost layer of the epidermis, or skin), often associated with the presence of an abnormal quantity of keratin,Kumar, Vinay; Fausto, Nelso; Abbas, Abul (2004) ''Robbins & Cotran Pathol ...

and death by asphyxiation. The fungus has been classified as a major factor in the decline in amphibian populations worldwide, but in Chile has been reported recently, in 2009. Other causes cited are competition that occurs between African clawed frog and helmeted water toad, introduced for sale in the market for frog legs.

References