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.
- Habitat Regions
- tropical
- freshwater
- Terrestrial Biomes
- rainforest
- 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.
- Other Physical Features
- ectothermic
- heterothermic
- bilateral symmetry
- Sexual Dimorphism
- sexes alike
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.
- Development - Life Cycle
- metamorphosis
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.
- Mating System
- polygynous
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.
- Key Reproductive Features
- iteroparous
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- fertilization
- oviparous
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.
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.
- Key Behaviors
- saltatorial
- natatorial
- nocturnal
- motile
- sedentary
- solitary
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.
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.
- Primary Diet
-
carnivore
- insectivore
- eats non-insect arthropods
- molluscivore
- 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.
- 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.
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.
Additional Links
Contributors
Tanya Dewey (editor), Animal Diversity Web.
Sunaina Khandelwal (author), University of Maryland, Baltimore County, Kevin Omland (editor, instructor), University of Maryland, Baltimore County.
- Ethiopian
-
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- tropical
-
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
- freshwater
-
mainly lives in water that is not salty.
- 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.
- ectothermic
-
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- 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.
- 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.
- polygynous
-
having more than one female as a mate at one time
- 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).
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- fertilization
-
union of egg and spermatozoan
- external fertilization
-
fertilization takes place outside the female's body
- oviparous
-
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
- saltatorial
-
specialized for leaping or bounding locomotion; jumps or hops.
- natatorial
-
specialized for swimming
- nocturnal
-
active during the night
- motile
-
having the capacity to move from one place to another.
- sedentary
-
remains in the same area
- solitary
-
lives alone
- visual
-
uses sight to communicate
- acoustic
-
uses sound to communicate
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- 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.
- pet trade
-
the business of buying and selling animals for people to keep in their homes as pets.
- food
-
A substance that provides both nutrients and energy to a living thing.
- 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).
- carnivore
-
an animal that mainly eats meat
- insectivore
-
An animal that eats mainly insects or spiders.
- molluscivore
-
eats mollusks, members of Phylum Mollusca
- 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.
References
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= .
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). 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). 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 .