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Oophaga histrionica

By Patrick Trepanowski

Geographic Range

Oophaga histrionica is found in tropical rainforests from western Ecuador, north through the region of Colombia occupied by the Choco tribe. (Zamora et al 1999)

Habitat

O. histrionica are found on the floor of tropical rainforests where moist, humid conditions are present. O. histrionica are found moving around on fallen branches, leaves of tropical plants and over the leaf litter on the ground of the forest. (Zamora, 1999; National Aquarium in Baltimore, 1999)

Physical Description

Harlequin poison dart frogs are small frogs, measuring only 1 to 1.5 inches (2.5 to 3.8 cm) (Staniszewski, 1995). The first individual was described in 1847 by Berthold, who described the frog as bright orange with black web markings all over the body (Zamora et al 1999). However, today there are numerous color morphs of O. histrionica recognized, some varying from valley to valley. The morphs range in base colors of bright to dull orange, yellow, red, white, and powder-blue. The web-like pattern over their body also varies in thickness. The reticulated pattern can range from a standard thin stripe width to speckled, incomplete lines to an all black frog with a few colored spots, making the frog appear to have a black base color when in fact the base color is that of the spots. The bright markings of O. histrionica probably act as a warning to potential predators. The skin glands of O. histrionica produce a highly toxic poison capable of repelling or even killing small predators. This toxin is collected from the prey of these frogs and then deposited in their skin. (Zamora et al 1999)

  • Sexual Dimorphism
  • sexes alike
  • Range length
    2.5 to 3.8 cm
    0.98 to 1.50 in

Development

Reproduction

Poison dart frogs will breed throughout the rainy season. The males attempt to attract females by perching on a leaf and giving a trilling, buzzing call. Once the male has attracted his mate, together they will search for a location to lay the eggs. The female lays her eggs on the surface of a leaf while the male follows behind her and deposits his sperm. Females may lay anywhere from 4 to 20 eggs (National Aquarium in Baltimore, 1999). Once the eggs are fertilized, the female will stay by her eggs to guard them. After about ten days, the tadpoles break free from the jelly-like egg mass and use their tails to swim onto the mother's back. The female will transfer the tadpoles one at a time to pockets of water, usually in the axils of bromeliads (air plants). O. histrionica is unique in how the tadpoles feed. O. histrionica are obligate egg feeders, meaning to insure proper development, the tadpole must eat infertile eggs from its mother (Zamora et al 1999). The female will return to the bromeliads every other day and deposit these infertile eggs into the water. The tadpoles need three months to complete metamorphosis. Once metamorphosis is complete, the juvenile frog will climb out of the bromeliad and begin terrestrial life on its own. (Staniszewski, 1995; Zamora et al., 1999; National Aquarium in Baltimore, 1999; and Ryan, 1999)

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)

Lifespan/Longevity

  • Average lifespan
    Status: captivity
    9.1 years
    AnAge

Behavior

These frogs are diurnal, being able to forage during the day without the threat of predators, due to the bright warning (aposematic) colors. The skin toxins are located over the entire surface of the poison dart frogs. (National Aquarium in Baltimore, 1999)

Food Habits

O. histrionica feeds on small invertebrates. Their primary food preferences are ants, termites, small beetles, and other small arthropods found in the leaf litter. To capture their prey, like other frogs, they rely on their sight and use a sticky, retractable tongue. Tadpoles feed on infertile eggs provided by their mother. (Zamora et al., 1999; National Aquarium in Baltimore, 1999)

Economic Importance for Humans: Positive

We can assume that poison dart frogs play an integral role in the rainforest ecosystem, acting as predators on small insects and other arthropods. The skin toxins of this frog are potentially dangerous to humans who handle them, but native tribespeople have used these toxins to poison tips of blowgun darts to facilitate hunting of small food animals.

Conservation Status

Rainforests are being destroyed at a rapid rate, and O. histrionica is found in no other habitat in the world. O. histrionica, and other species of Dendrobatids, may be the first poison dart frogs placed on an endangered species list (National Aquarium in Baltimore, 1999). Most poison dart frogs are extremely difficult to breed in captivity because of the specific habitat requirements that are hard to match (Zamora et al., 1999), and this species is particularly difficult (Staniszewski, 1995). To preserve the species, the deforestation of rainforest must slow and eventually end. (Zamora et al 1999, National Aquarium in Baltimore 1999)

Other Comments

The Choco tribe, along with other native groups, coat their weapons (dart tips) with the secretions of O. histrionica and related frogs. The points are rolled in secretions collected from poison dart frogs and allowed to dry. The tip of the weapon will remain potent for about a year. The toxin found in their skin blocks neural transmission at the acetylcholine receptor of the neuro-muscular junction (Ryan, 1997). The toxin of poison dart frogs is strong enough to kill small animals such as monkeys, and can also cause serious neurological harm to humans, should the toxin come in contact with the blood stream. (Ryan, 1997; National Aquarium in Baltimore, 1999; and Cogger and Zweifel, 1998)

Contributors

Patrick Trepanowski (author), Michigan State University, James Harding (editor), Michigan State University.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

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.

ectothermic

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

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

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.

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.

motile

having the capacity to move from one place to another.

native range

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

poisonous

an animal which has a substance capable of killing, injuring, or impairing other animals through its chemical action (for example, the skin of poison dart frogs).

polymorphic

"many forms." A species is polymorphic if its individuals can be divided into two or more easily recognized groups, based on structure, color, or other similar characteristics. The term only applies when the distinct groups can be found in the same area; graded or clinal variation throughout the range of a species (e.g. a north-to-south decrease in size) is not polymorphism. Polymorphic characteristics may be inherited because the differences have a genetic basis, or they may be the result of environmental influences. We do not consider sexual differences (i.e. sexual dimorphism), seasonal changes (e.g. change in fur color), or age-related changes to be polymorphic. Polymorphism in a local population can be an adaptation to prevent density-dependent predation, where predators preferentially prey on the most common morph.

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.

References

Cogger, H., R. Zweifel. 1998. Encyclopedia of Reptiles and Amphibians. San Diego, California: Academic Press.

National Aquarium in Baltimore, 1997. "Poison dart frog--amazing amphibians" (On-line). Accessed December 8, 1999 at http://www.aqua.org/animals/species/prpdfrog.html.

Ryan, M. 1997. "Dendrobatid Biology" (On-line). Accessed November 14, 1999 at http://www.utexas.edu/courses/herps/ryan/dendrobatid.html.

Staniszewski, M. 1995. Amphibians in Captivity. Neptune City, New Jersey: T.F.H. Publications, Inc..

Zamora, Z., R. Gagliardo, C. Nishihira. June/July 1999. Harlequin Poison Dart Frogs. The Vivarium, Vol 10 No 4: 22-27.

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