P. terribilis 'Orange'

Phyllobates terribilis

The Golden Poison Dart Frog
Myers, Daly and Malkin, 1978

 Family:   Dendrobatidae
Genus:   Phyllobates
Species: Phyllobates terribilis
Origin/Distribution:  Pacific Coast of Colombia

Distribution/Habitat
P. terribilis can be found in the warm, humid, lowland forests of the western foothills of the Andes on a “northerly inclined spur of the Cordillera Occidental” in Pacific coastal Colombia. The elevation in their range varies from 90-200 m (approx 295-656 ft.) above sea level.  The terrain is wet, rough, rocky further characterized by nearly vertical slopes. They can be found throughout these forest on drier ridge tops as well as on the moist slopes, and tend to live near smaller streams, as the larger streams have either been cleared for agriculture or is dense secondary growth forest.[1]

Description
Big is beautiful!  As Dendrobatids go, P. terribilis is quite large at 4.5 – 5 cm (approx. 1 ¾ – 2 in.) snout to vent.  Their colors, which reflect specific locales, range from light metallic, sometimes silvery-green  (known by hobbyists as the “mint’ morph),  to bright yellow to pure orange.  They are typically solid-colored frogs with varying amounts of black on their feet; however, there are also frogs whose colors fall between these ranges, i.e. greenish-yellow or yellow-orange or even combinations of these colors.  This may indicate that there are or have been territorial convergences of the populations.  Newly developed froglets and juveniles are dark grayish-brown to black with 2 broad parallel dorsal stripes that are greenish to gold depending on the color morph/locale of the frog.  At this stage the frogs resemble P. aurotaenia and P. vittatus without the blue dorsal, ventral and leg flecking.

Q:  Why do terribilis sit out in the open in broad daylight?
A:  Because they can.

To date, Phyllobates terribilis is thought by scientists to be the most poisonous vertebrate on earth.  Of the three species in the genus Phyllobates that are actually used by certain indigenous peoples of Colombia (specifically, the Chocó and Cofán) to poison the tips of hunting darts, P. terribilis is by far the deadliest.  One need only wipe a dart tip across the back of an adult frog, and a weapon will have been created that can remain lethal for more than 3 years.

P. terribilis produces the steroidal alkaloids batrachotoxin, homobatrachotoxin, and batrachotoxinin A, and is nearly 2,000 times more poisonous than other species in the Dendrobatid family.  “These compounds are extremely potent modulators of voltage-gated sodium channels, acting to keep the channels open and depolarizing nerve and muscle cells irreversibly, leading to arrhythmias, fibrillation, and eventually cardiac failure” (Albuquerque and Daly 1977).[2]

The range of toxins produced per frog is 700-1900 micrograms, 1100 being the average.  200 micrograms is the estimated lethal dose for humans, thus a single wild-caught frog has the potential to kill 10 humans, and as many as 20,000 laboratory mice.[3]

As is typical of Dendrobatids, the toxic alkaloids are diet derived and dependant.  Captive frogs deprived of their natural diet gradually decrease in toxicity.  Myers et al note that, “Frogs that had been held in captivity for periods ranging from three weeks up to one year had toxicities of about 50% of recently caught specimens, with frogs maintained in captivity for three years still maintaining toxicity at about 40% the level of recently captured animals.”[4]  This suggests that after a sharp initial decline in toxicity, long-term captives retained enough poison to remain lethal.

This may account for P. terribilis’ bold behavior.  They can be seen in open areas of their rainforest habitat, disinclined to retreat when approached.  It is said that if disturbed a hop or two to the side is all one might expect.  On the other hand, young metamorphs and juveniles are skittish and can be difficult to spot.  Emboldened as their poisons are acquired and intensified, these frogs eventually become fearless.  Interestingly, captive-bred terribilis, which never acquire the deadly alkaloids exhibit these same behaviors, suggesting that these inclinations are genetic.

Natural predators
Leimadophis (Liophis) epinephelus, a small, thin Amazonian colourbrid snake, is a natural predator of Dendrobatids and other anurans.  It is also the only known predator of P. terribilis.  It is resistant to the frogs’ toxins; however, it is not immune to them.  A snake that makes a meal of an adult terribilis will not necessarily survive, thus the snake’s noted preference for younger, less toxic frogs.

Conservations Status
Endangered.  Some of the causes for this are the general habitat alteration and loss, habitat modification from deforestation (i.e. for logging, farming & agriculture), habitat fragmentation, and local and foreign pesticides, fertilizers, and pollutants.  Unfortunately none of its habitat is currently protected.

Phyllobates terribilis ‘Mint’
Phyllobates terribilis ‘Yellow’

Phyllobates terribilis ‘Orange’

Phyllobates terribilis ‘Black-footed Orange’

 



[1] Meyers et al 1978

[2] Albuquerque and Daly 1977

[3] Myers et al 1978

[4] Myers et al 1978