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Conraua goliath

By Sunaina Khandelwal

Geographic Range

The geographic range of goliath frogs is restricted to coastal, equatorial Guinea and Cameroon in West Africa.

Habitat

Goliath frogs are found in or near fast-flowing rivers and waterfalls in dense, humid and relatively high-temperature rain forests. The water is usually clean, oxygen rich, slightly acidic and usually around 67°F. The presence of larval food also determines where goliath frogs occur. ("Conraua Goliath", 2008; "Goliath Frog", 1996; "Goliath Frog(Conraua Goliath)", 2005; Amiet, 2007; Gray, 2003; "True Frogs: Ranidae - Goaliath Frog(conraua Goliath): Species Accounts", 2008; "Goliath Frog(Conraua Goliath)", 2006)

  • Aquatic Biomes
  • rivers and streams

Physical Description

Goliath frogs are the largest frogs on Earth. They are from 17 to 32 cm long and from 600 to 3250 grams in weight. They have a flattened, wide body with a triangular head. Their dorsal skin is granular and greenish brown and the ventral skin is a lighter yellowish green. The hind legs are long, front legs are shorter and stout, and all of the feet are extensively webbed. Their eyes can be nearly 2.5 cm in diameter. ("Goliath Frog", 1996; "Goliath Frog(Conraua Goliath)", 2005; Gray, 2003; "True Frogs: Ranidae - Goaliath Frog(conraua Goliath): Species Accounts", 2008; Sandmeier, 2002; "Goliath Frog(Conraua Goliath)", 2006)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    600 to 3250 g
    21.15 to 114.54 oz
  • Range length
    17 to 32 cm
    6.69 to 12.60 in

Development

Goliath frog tadpoles are not much larger than those of other frogs, but the majority of growth occurs in the first 75 to 90 days of development. The goliath frog's young tadpoles are not much larger than other frogs'. So the majority of the growth process occurs during the 75-90 days. As in other frogs, goliath frog larvae undergo metamorphosis to become adult frogs. (Gray, 2003; "True Frogs: Ranidae - Goaliath Frog(conraua Goliath): Species Accounts", 2008; Sandmeier, 2002; "Goliath Frog(Conraua Goliath)", 2006)

Reproduction

Little is known about goliath frog mating systems. The little research that has been done suggests that male goliath frogs perform the calling ritual differently from most other frogs. Instead of sucking in air into vocal sacs and blowing it out to make calls, goliath frogs hold the mouth open to make a long whistling noise. Goliath frogs do not have vocal sacs. Females then follow this noise to the male. ("Goliath Frog", 1996; "True Frogs: Ranidae - Goaliath Frog(conraua Goliath): Species Accounts", 2008; "Goliath Frog", 1996; "True Frogs: Ranidae - Goaliath Frog(conraua Goliath): Species Accounts", 2008)

Female goliath frogs lay several hundred eggs at a time that are about 3.5 mm in diameter. They stick to vegetation at the bottom of the rivers and streams in which they reproduce. The eggs then hatch into tadpoles that grow to about 5 cm long over the next 75 to 90 days. There is no information about the seasonality or frequency of breeding or time to sexual maturity. ("Goliath Frog(Conraua Goliath)", 2005; "True Frogs: Ranidae - Goaliath Frog(conraua Goliath): Species Accounts", 2008; Sandmeier, 2002; "Goliath Frog(Conraua Goliath)", 2006)

There is no parental investment in goliath frog young after the female deposits the eggs after fertilization.

  • Parental Investment
  • no parental involvement
  • pre-fertilization
    • provisioning
    • protecting
      • female

Lifespan/Longevity

Lifespan of goliath frogs is not well documented, although individuals in the wild seem to live longer than those in captivity. ("Goliath Frog", 1996; "Goliath Frog", 1996)

Behavior

Goliath frogs are most active at night as they search for food along rivers. Younger frogs spend most of their time underwater whereas older frogs occasionally bask on rocks. ("Goliath Frog(Conraua Goliath)", 2006)

Communication and Perception

Goliath frogs do not have vocal sacs and are often considered mute. As a mating call, goliath frogs hold their mouths open and make a whistling noise. ("Goliath Frog", 1996; "Goliath Frog(Conraua Goliath)", 2005; Gray, 2003; "True Frogs: Ranidae - Goaliath Frog(conraua Goliath): Species Accounts", 2008; "Goliath Frog(Conraua Goliath)", 2006)

Food Habits

Adult goliath frogs feed on insects, crustaceans, fish, mollusks, small mammals and amphibians, including newts, salamanders, and smaller frogs. Goliath tadpoles are vegetarians and feed only on one aquatic plant, Dicraea warmingii, found only near waterfalls and streams. ("Conraua Goliath", 2008; "Goliath Frog", 1996; "Goliath Frog(Conraua Goliath)", 2005; Amiet, 2007; Gray, 2003; "True Frogs: Ranidae - Goaliath Frog(conraua Goliath): Species Accounts", 2008; Sandmeier, 2002; "Goliath Frog(Conraua Goliath)", 2006)

  • Animal Foods
  • mammals
  • amphibians
  • insects
  • terrestrial non-insect arthropods
  • mollusks
  • Plant Foods
  • algae

Predation

The greenish brown dorsal skin of goliath frogs camouflages them well with the wet-moss covered rocks that adult frogs bask on. Goliath frogs are only known to be preyed on by humans, although other predators are possible. ("Goliath Frog(Conraua Goliath)", 2005; "Goliath Frog(Conraua Goliath)", 2006)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Being carnivores, frogs occupy an intermediate position in food webs and their numbers can be indicators of the health of a broader ecosystem. Generally frogs regulate insect populations and also feed on other frogs, fish, small mammals and other small amphibians. Frogs in turn serve as food for birds, reptiles and mammals.

Economic Importance for Humans: Positive

Because of their size, goliath frogs are valued for the international pet and zoo trade. They are also a valuable food source for local communities. ("Big frog--really big: but vulnerable to deforestation, pollution, cook pots. (Conservation)", 2003; "Goliath Frog", 1996; "Goliath Frog(Conraua Goliath)", 2005; Gray, 2003; Sandmeier, 2002; "Goliath Frog(Conraua Goliath)", 2006)

Economic Importance for Humans: Negative

There are no known adverse effects of goliath frogs on humans

Conservation Status

The IUCN sites goliath frogs as an endangered species because of a 50% decline in population size in the last three generations. The most significant threats to the species include hunting for food, destruction of forest habitat because of human settling, sedimentation, commercial logging and agriculture, and exportation for zoos, the pet trade, and competitive frog races. Some of the goliath frogs natural habitats have been declared protected areas including the Monte Alen National Park in Equatorial Guinea. Three wildlife sanctuaries in Littoral Province have also been approved as protected areas in Cameroon. The Equatorial Guinean government has set a limit of 300 on the frogs that may be exported per year. However, local conservation efforts and captive-breeding programs also need to be considered in order to maintain population sizes. ("Big frog--really big: but vulnerable to deforestation, pollution, cook pots. (Conservation)", 2003; "Conraua Goliath", 2008; Amiet, 2007; Gray, 2003; "True Frogs: Ranidae - Goaliath Frog(conraua Goliath): Species Accounts", 2008)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Sunaina Khandelwal (author), University of Maryland, Baltimore County, Kevin Omland (editor, instructor), University of Maryland, Baltimore County.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

acoustic

uses sound to communicate

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.

carnivore

an animal that mainly eats meat

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

ectothermic

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

external fertilization

fertilization takes place outside the female's body

fertilization

union of egg and spermatozoan

food

A substance that provides both nutrients and energy to a living thing.

freshwater

mainly lives in water that is not salty.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

molluscivore

eats mollusks, members of Phylum Mollusca

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

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

nocturnal

active during the night

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

polygynous

having more than one female as a mate at one time

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

saltatorial

specialized for leaping or bounding locomotion; jumps or hops.

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

threatened

The term is used in the 1994 IUCN Red List of Threatened Animals to refer collectively to species categorized as Endangered (E), Vulnerable (V), Rare (R), Indeterminate (I), or Insufficiently Known (K) and in the 1996 IUCN Red List of Threatened Animals to refer collectively to species categorized as Critically Endangered (CR), Endangered (EN), or Vulnerable (VU).

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

References

2003. Big frog--really big: but vulnerable to deforestation, pollution, cook pots. (Conservation). National Georgraphic, 203/6: XVI(3). Accessed April 22, 2008 at http://galenet.galegroup.com/servlet/SciRC?ste=1&docNum=A104363588.

2008. "Conraua Goliath" (On-line). Wikipedia. Accessed April 22, 2008 at http://en.wikipedia.org/wiki/Goliath_frog.

2005. Goliath Frog(Conraua Goliath). W Beacham, B Freedman, F Castranova, eds. Beacham's Guide to International Endangered Species, Vol. 3. Detroit: Thomsan Gale. Accessed April 22, 2008 at http://galenet.galegroup.com/servlet/SciRC?ste=1&docNum=CV2644500268&finalAuth=true.

Thomson Gale. 2006. Goliath Frog(Conraua Goliath). B Freedman, ed. Encyclopedia of Endangered Species, Vol. 1. Detroit: Accessed April 22, 2008 at http://galenet.galegroup.com/servlet/SciRC?ste=1&docNum=CV2644710244.

1996. "Goliath Frog" (On-line). American Museum of Natural History. Accessed April 22, 2008 at http://www.amnh.org/nationalcenter/Endangered/frog/frog.html.

Net Industries. 2008. "True Frogs: Ranidae - Goaliath Frog(conraua Goliath): Species Accounts" (On-line). Accessed April 22, 2008 at http://animals.jrank.org/pages/190/True-Frogs-Ranidae-GOLIATH-FROG-Conraua-goliath-SPECIES-ACCOUNTS.html.

Amiet, L. 2007. "Conraua Goliath - Endangered" (On-line). IUCN Red List of Threatened Species. Accessed April 22, 2008 at http://www.iucnredlist.org/search/details.php/5263/all.

Gray, A. 2003. "Conraua Goliath" (On-line). Arkive. Accessed April 22, 2008 at http://www.arkive.org/species/GES/amphibians/Conraua_goliath/more_info.html.

Sandmeier, F. 2002. "Conraua Goliath" (On-line). AmphibiaWeb. Accessed April 22, 2008 at http://amphibiaweb.org/cgi-bin/amphib_query?rel-genus=like&rel-species=like&rel-common_name=like&rel-family=equals&rel-ordr=equals&rel-isocc=like&rel-description=like&rel-distribution=like&rel-life_history=like&rel-trends_and_threats=like&rel-relation_to_humans=like&rel-comments=like&rel-submittedby=like&query_src=aw_search_index&max=200&orderbyaw=Family&where-genus=conraua&where-species=goliath&where-common_name=&where-family=any&where-ordr=any&where-isocc=&rel-species_account=matchboolean&where-species_account=&rel-declinecauses=equals&where-declinecauses=any&rel-iucn=equals&where-iucn=&rel-cites=equals&where-cites=&where-submittedby=.

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