Golden Poison Frog

Phyllobates terribilis, or the Golden Poison Frog, is a poison dart frog endemic to the pacific coast of Colombia. This amphibian of the dendrobatidae family is currently considered the most poisonous vertebrate worldwide.^[1] The optimal habitat of P. terribilis is the rainforest with high rain rates (5 m3 or more), altitude between 100-200 m, temperature of 26°C, and relative humidity of 80-90%.

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Description

P. terribilis can reach a size of 5 cm in adulthood. The adults are brightly colored, without dark spots. The frog's color pattern is aposematic (which is a warning pigmentation to warn predators of its toxicity). The frog has tiny adhesive disks in its toes which aid climbing of plants. It also has a bone plate in the lower jaw, which gives the frog the appearance of having teeth, a distinctive feature not observed in the other species of Phyllobates. The frog is normally diurnal (active during the day). Phyllobates terribilis occurs in three different color varieties or morphs:

Mint Green

This morph exists in the La Brea area of Colombia and is the most common form seen in captivity. The name "mint green" is actually rather misleading as the frogs of this morph can be metallic green, pale green, or white.

Yellow

The yellow morph of Phyllobates terribilis is the reason it has the common name, Golden poison dart frog. Yellow terribilis are found in Quebrada Guangui, Colombia. These frogs can be pale yellow to a deep, golden yellow color. A frog sold under the name "Gold terribilis" was once believed to be a deeper yellow terribilis. However, genetic tests have proven these frogs to be a uniform colored morph of Phyllobates bicolor.

Orange

While not as common as the other two morphs, orange terribilis exist in Colombia as well. They tend to be a metallic orange or yellow-orange color, with varying intensity.  

Reproduction

Sexual maturity is reached at around 13-18 months (sizes around 37mm for males, and 41mm for females). Mating occurs during the season of most intense rains (monsoon). The male calls the female with a buzzing song, and the femal deposits the eggs (13-14 eggs usually) under leaves, where the male fertilizes them. Both the male and the female check the eggs often, to maintain the humidity or to protect them from predation. After the eclosion the male carries the tadpoles on its back, until they finish their metamorphosis (about 2 months).

Feeding

The main natural sources of food of P. terribilis are the ants from Brachymyrmex and Paratrechina genera, but many kinds of insect and other small invertebrates can be devoured, specially termites and beetles. This frog is considered the most voracious of the dendrobatidae family.^[2]

In captivity, the frog is fed with Drosophila fruit flies, cochineals and crickets (Gryllidae), the larvae of various insects, and other small live invertibrate foods. An adult frog can eat food items much larger in relation to its size than most other frogs.

Poison

The Golden Poison Frog's alkaloid poison, one of a number of poisons common to dart frogs (batrachotoxins), prevents nerves from transmitting impulses, leaving the muscles in an inactive state of contraction. This can lead to heart failure or fibrillation. Alkaloid batrachotoxins can be stored by frogs for years after the frog is deprived of a food-based source, and such toxins do not readily deteriorate, even when transferred to another surface. Chickens and dogs have died from contact with a paper towel on which a frog had walked.^[3][4]

The average dose carried will vary between locations, and consequent local diet, but the average wild P. terribilis is generally estimated to contain about one milligram of poison, enough to kill about 10,000 mice. This estimate will vary in turn, but most agree that this dose is enough to kill between 10 and 20 humans.^[5]

This extraordinarily lethal poison is very rare. Batrachotoxin is only found^[6] in three poisonous frogs of Colombia (genus Phyllobates) and two poisonous birds of Papua New Guinea: Pitohui dichrous and Ifrita kowaldi. Other related toxins are Histrionicotoxin and Pumiliotoxin, which are found in frog species from the genus Dendrobates.^[7]

The golden poison frog, like most other poisonous frogs, stores its poison in skin glands. Due to their poison, the frogs taste vile to predators; P. terribilis' poison kills whatever eats it, except for a snake, Liophis epinephelus. This snake is resistant to the frog's poison, but is not completely immune.

The poisonous frogs are perhaps the only creatures possessing enough resistance to accumulate this poison in even minuscule quantities. Batrachotoxin attacks the sodium channels of the cells. Through the ages, the frog has evolved special sodium channels that the poison can not harm.

Since easily purchasable foods such as fruit flies and extra-small crickets are not rich in the alkaloids required to produce batrachotoxins, captive frogs do not produce toxins and they eventually lose their toxicity in captivity. In fact, many hobbyists and herpetologists have reported that most dart frogs will not consume ants at all in captivity, though ants constitute the larger portion of their diet in the wild. This is likely due to the unavailability of the natural prey species of ants to captive frog keepers. Though all poison frogs lose their toxicity when deprived of certain foods, and captive-bred Golden Poison Frogs are born harmless, a wild-caught poison frog can retain alkaloids for years. It is not clear which prey species supplies the potent alkaloid that gives golden poison frogs their exceptionally high levels of toxicity, or whether the frogs modify another available toxin to produce a more efficient variant, as do some of the frog's cousins from the Dendrobates family.

Thus, the high toxicity of P. terribilis appears due to consumption of a small insect or other arthropod, which may truly be the most poisonous creature on Earth.^[5]

Scientists have determined the mysterious insect probably is a small beetle from the family Melyridae. The beetle produces the same toxin found in P. terribilis. The beetle family Melyridae is cosmopolitan. Its relatives in Colombian rainforests could be the source of the batrachotoxins found in the highly toxic Phyllobates frogs of that region.^[8]

Poison frog and the indigenous people

P. terribilis is a very important animal to the local indigenous cultures, such as the Choco Emberá people in Colombia's rainforest. The frog is the main source of the poison in the darts used by the natives to hunt their food.

The Emberá people carefully expose the frog to the heat of a fire, and the frog exudes small amounts of poisonous fluid. The tips of arrows and darts are soaked in the fluid, and keep their venomous effect for over two years.^[9]

Captive care

Like the other poison dart frogs, Phyllobates terribilis is harmless when raised away from its natural food source. They are a popular rainforest vivarium subject and are somewhat easier to feed than some dart frogs. Larger species of fruit flies, small crickets, waxworms, small mealworms, termites, and phoenix worms can be used if supplemented with calcium and other minerals. The temperature should be in the low to mid 20s (°C). They are sensitive to high heat and suffer from a condition called wasting syndrome if overheated for too long. They require high humidity as they come from one of the world's most humid rainforests. P. terribilis is not as territorial as most dart frogs and can successfully be kept in groups. However, they require a slightly larger enclosure due to their adult size, similar to the enclosure size used for Dendrobates tinctorius. Occasional disputes may occur, but injuries are rare, and deaths have not been reported as the result of such conflicts.

• The True Poison-Dart Frog: The Golden Poison Frog Phyllobates terribilis

• Beetle May Be Source of Frog's Poison

References

• Bolívar & Lötters (2004). Phyllobates terribilis. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 11 May 2006. Database entry includes a range map and justification for why this species is endangered