Golden Poison Frog

Phyllobates terribilis is a small frog (though large for a dendrobatid), with adult females having a maximum snout-vent length of 47 mm, and adult males reaching 45 mm in snout-vent length. Males mature at 37 mm while females mature at 40-41 mm. The snout is sloping and rounded in lateral profile, and bluntly rounded to truncate in dorsal view. The canthus rostralis is rounded, and the loreal region is both vertical and slightly concave. The tympanum is concealed posterodorsally. Hands and feet lack webbing and fringe. Fingers and toes terminate in moderately expanded discs; the disc of the third finger is expanded to the same degree in both males and females. If measured while appressed, the third finger is longest with the fourth, first, and second following in decreasing or approximately equal length; if measured from the base, the third finger is longest and the first finger is next while fingers 2 and 4 are roughly equal. Hands have a large, low, rounded tubercle on the palm. An inner metacarpal tubercle is present on the base of the first finger, with one subarticular tubercle on each of fingers 1 and 2, and two subarticular tubercles on fingers 3 and 4. On the feet, the relative length of the toes is 4>3>5>2>1. The distal third of the tarsus is ridged, with the ridge continuous from the inner metarsal tubercle to the tarsal tubercle. Toes 1 and 2 each bear one subarticular tubercle, toes 3 and 5 have two subarticular tubercles, and toe 4 bears three subarticular tubercles. Phyllobates terribilis skin is smooth to somewhat rugose or finely granular, becoming noticeably rugose and coarsely granular on the upper hind limbs. Teeth are present on the maxillary arch. Males have a shallow subgular vocal sac that is indicated by small expansion wrinkles at the base of the throat, and well-developed paired vocal slits on the floor of the mouth. (Myers et al. 1978). The dorsal coloration on adult specimens of Phyllobates terribilis is bright golden yellow or golden orange, or pale metallic green, depending on the location of collection. Occasional individuals were deep orange or pale greenish yellow. Ventrally the color is the same as or slightly lighter than the dorsal color, except for the underside of the hands and feet, which are black, and the undersides of the thighs, which have a black seat patch. There is also a black crease at the axilla and groin. The eyes, nares and digit tips are black. There is usually black edging on the lower rim of the tympanum. In many individuals the mouth is edged with black, and the creases of limb articulations are often black. Males generally have some gray coloration on the base of the throat. In some individuals there is also a light gray suffusing the axilla and groin, as well as the posterior of the venter and the concealed part of the shank. In individuals that are pale metallic green in overall color, the venter may be slightly bluish green and the concealed part of the shank is sometimes a definite blue-green. Variation in ground color hue was associated with microgeographic variation (i.e. frogs collected from a given ridge or slope area tended to be the same hue) (Myers et al. 1978). Phyllobates terribilis tadpoles measure an average of 4.1 mm in body length and 11.1 mm in total length at hatching. At stage 37 (with well-developed hind legs), tadpoles have reached an average size of 12.6 mm in body length and 35.4 mm in total length. The head and body are depressed, with body width being greater than body depth. Eyes and nostrils are dorsal, and the eyes are directed dorsolaterally. The spiracle is sinistral and the vent is dextral (in some stage 25 larvae, the vent was located medially). The mouth is anteroventral with finely serrated beaks and 2/3 tooth formula; the second row of teeth above the mouth has a gap above the beak. The oral disc is anteriorly nude and indented laterally, with the lateral and posterior edges of the disc having one or two rows of papillae, depending on the developmental stage of the larva. Mouthparts are incompletely developed at stage 25 (the stage at which many dendrobatid tadpoles mount onto the back of the attendant parent frog). At stage 25 the denticles begin to keratinize and beak serrations are only just beginning to develop. Stage 25 larvae have a single row of papillae while stage 27 and older larvae have two rows (similar to the ontogenetic changes seen in tadpole oral papillae of some hylid frogs) (Myers et al. 1978). Newly hatched tadpoles are gray on the bodies and throats with paler gray tails and tail fins, with tiny flecks on the body and tail. At stage 26 the tail fins begin to become essentially transparent; there is weak pigmentation along the base of the fins and sparse flecking. At stage 37 the body color changes to blackish gray. Dense flecks are present dorsally and concentrate into paired dorsolateral stripes that run from the snout over the eyes to the base of the tail. To the naked eye the dorsolateral stripes look gray on a grayish black body, but under magnification the stripes appear pale bronze. At stage 42 (when forelimbs appear) the body is black and the dorsolateral stripes are brighter bronze to bronze-gold (Myers et al. 1978). Juvenile frogs are black in color, with gold dorsolateral stripes. This species undergoes an ontogenetic color change. As the frogs reach maturity, the dorsolateral stripes disappear, and the body becomes a more brightly colored uniform golden yellow. The bright golden dorsal coloration is achieved by 18 weeks, when the frog is about 21 mm in SVL, with the venter taking another several weeks to reach the same bright color. Since the frog reaches adult size in somewhat more than a year, the adult coloration is actually attained fairly early. Juvenile P. terribilis resemble P. aurotaenia in that both are black with paired gold dorsolateral stripes. However, juvenile P. terribilis can be distinguished by the lack of blue or green ventral spotting (present in juvenile P. aurotaenia). (Myers et al. 1978). The juvenile pattern of light stripes on a dark background is also lost in P. bicolor upon reaching maturity, but is retained into adulthood in the other members of the P. bicolor group, P. aurotaenia, P. lugubris and P. vittatus (Myers et al. 1978; Silverstone 1976).This species produces the steroidal alkaloids batrachotoxin, homobatrachotoxin, and batrachotoxinin A. These compounds are extremely potent modulators of voltage-gated sodium channels, acting to keep the channels open and depolarizing nerve and muscle cells irreversibly, potentially leading to arrhythmias, fibrillation, and eventually cardiac failure (Albuquerque and Daly 1977). When accidentally transferred onto human facial skin, these toxins have been reported to cause a burning sensation lasting several hours (Myers et al. 1978). Batrachotoxin by itself is also capable of inducing numbness (see below for Myers' (1978) description of the effect of tasting P. vittatus), through its profound effects on a specific voltage-gated sodium channel (Na 1.8) known to be involved in pain reception. Thus batrachotoxin might be useful to develop as a topical pain-relief medication (Bosmans et al. 2004). The combination of batrachotoxin and homobatrachotoxin is produced in quantities up to 1900 micrograms per frog, which is at least 20-fold more than other toxic species in the family Dendrobatidae. The range of batrachotoxin-homobatrachotoxin produced by individual frogs was 700-1900 micrograms, with an average of 1100 micrograms per frog. The lethal dose of batrachotoxin-homobatrachotoxin for a 20 gram white laboratory mouse is .05 micrograms when injected subcutaneously. Thus one P. terribilis frog skin contains enough toxin to kill about 22,000 mice. The lethal dose of batrachotoxin for humans is not known but has been estimated at 200 micrograms, with a single frog thus potentially holding enough poison to kill about 10 humans. Wild-caught 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 (Myers et al. 1978). In contrast, poison frogs born and reared in captivity do not contain toxins in their skin, although they can accumulate alkaloid toxins if these are part of the diet (Daly et al. 2004). Tadpoles did not contain batrachotoxin but a juvenile of 27 mm SVL was found to contain 200 micrograms of toxin, implying that the batrachotoxin alkaloids are synthesized or sequestered after metamorphosis (Myers et al. 1978). The toxins are concentrated in granular glands, which are most dense on the dorsal skin surfaces of the frog (Dumbacher et al. 2000). In contrast, the related species P. bicolor is much less toxic, containing from 17-56 micrograms of batrachotoxin-homobatrachotoxin per frog, with an average of 47 micrograms per individual. Despite P. bicolor being more brightly colored, larger, and more openly active than P. aurotaenia, the two species are thought to be roughly the same in toxicity levels (Myers et al. 1978). The more distantly related Central American species Phyllobates vittatus and P. lugubris also produce batrachotoxins but at much lower quantities. Despite these lower levels of toxin, Myers et al. (1978) reported that tasting the back of P. vittatus gave the human taster a sensation of near-numbness of the tongue, followed by a distinctly unpleasant tightening in the throat. Interestingly, batrachotoxins have also been found in feathers, but not the skin, of multiple species of passerine birds from New Guinea (particularly Pitohui dichrous, P. kirhocephalus, and Ifrita kowaldi) (Dumbacher et al. 2000). Breast, belly, and leg feathers show the highest toxin concentrations. Both toxin levels and toxin profiles in these birds vary considerably from population to population and can also change seasonally, implying that these toxins are acquired or synthesized from an environmental (dietary) source (Dumbacher et al. 2000). This source is most likely beetles of the genus Choresine (family Melyridae), which contain batrachotoxins and have been found in the stomach contents of New Guinea's toxic passerine birds. The family Melyridae is cosmopolitan and thus beetles could potentially be the source of the Phyllobates toxin as well (Dumbacher et al. 2004). Dietary arthropods (formicine ants, myrmecine ants, and in Madagascar, ponerine ants, as well as the siphonotid millipede Rhinotus purpureus) are known to provide defensive alkaloids to other toxic dendrobatid and mantellid frogs (Clark et al. 2005).

Golden Poison Frogs can be found in the western foothills of the Andes on a “northerly inclined spur of the Cordillera Occidental” in Pacific coastal Colombia. The terrain is rough and hilly, with mostly steep, even perpendicular slopes. Elevation in their range varies from 90-200 m above sea level. They live in rainforest, occurring throughout the forest both on drier ridge tops and on moister slopes. They tend to live near smaller streams since forest along the larger streams has either been cleared for agriculture or is dense secondary growth forest (Myers et al. 1978).

This species avoids secondary growth and cultivated areas, and prefers primary growth forest, making it sensitive to human land use. It is not prevalent along larger streams in its range, due to development in the form of plantain fields, or secondary growth from previous forest resource utilization. Major threats include pollution from illegal spraying of crops, and deforestation (Myers et al. 1978).

This species, like all other members of the family Dendrobatidae, is diurnal. It is also terrestrial, preferring to sit on the ground or perched only a few centimeters above the ground on tree roots or ground litter. They are noticeably bolder than other poison dart frogs and are found out in the open. When disturbed, they will usually only hop away rather than try and hide. While these frogs normally are solitary in the wild, they have been occasionally observed in pairs. Their calls are long sustained trills, consisting of a rapid succession of individual notes uttered at a rate of 13 per second, with a dominant frequency of 1.8 kHz. This frequency is lower than that of P. aurotaenia, P. bicolor, P.lugubris and P. vittatus (Myers et al. 1978). Eggs are laid terrestrially in small clutches of less than 20. Larvae, at developmental stage 25, are transported to pools on the backs of the male frogs. Male frogs have been observed carrying up to nine larvae simultaneously (Myers et al. 1978). The populations appear to be large and dispersed through the forest, with both adults and juveniles found on the forest floor, although juveniles appear to be relatively rare (2.5% of all specimens collected). Recruitment appears to be low since clutch size is small and few nurse frogs were observed carrying tadpoles, yet P. terribilis adults were fairly abundant at the type locality. This species takes more than a year to attain sexual maturity and is relatively long-lived (five years in captivity) (Myers et al. 1978). Given its toxicity, Phyllobates terribilis seems likely to have few predators other than the snake Leimadophis epinephelus. This snake has a high resistance to various anuran toxins (zetekitoxin from Atelopus zeteki, atelopid toxins from Atelopus elegans, piperidine alkaloids from Dendrobates auratus, and batrachotoxins from Phyllobates sp.). It is not a large snake (500 mm in total length); since adult Phyllobates terribilis frogs are fairly stocky and quite toxic, these snakes may only consume the juvenile P. terribilis and not the adults (Myers et al. 1978). During feeding in captivity, frogs may clasp each other around the head (cephalic clasping) or sometimes the body. Interestingly, Phyllobates terribilis males have been observed in captive aggressive behavior to press the upper surfaces of their hands against their opponent's chin (rather than grasping the other frog's head with the palms contacting the head). (Myers et al. 1978).

Phyllobates terribilis is the most highly toxic of all frogs, and is one of three species known to be used by native Colombians such as the Chocó and Cofán to poison their blow-gun darts (the other species being P. aurotaenia and P. bicolor). Once P. terribilis has been captured, the darts are rubbed over the skin of the live frog to collect the poison (in contrast to the other two Phyllobates species which are impaled on sticks and sometimes heated, to maximize the amount of toxic secretions). The poisoned darts are then used for hunting (Myers et al. 1978).

Golden poison frogs have a variety of bright vibrant colors that cover their entire bodies, from mint green to yellow to orange and sometimes white. Yellow or deep yellow, is the most common color seen, giving them their common name. Phyllobates terribilis is the most toxic species of frog. Unlike most other members of the Family Dendrobatidae, Phyllobates terribilis has uniform body coloration, rather than dark spots and stripes, as in their relatives Phyllobates aurotaenia , Phyllobates lugubris and Phyllobates vittatus. Adults are more brightly colored than young, which have the same primitive pattern of most other members of the family Dendrobatidae. They have dorsolateral stripes on dark bodies until they mature. By the time they reach adulthood, their coloration has changed to a single bright color.

An easy way to identify these frogs is by the odd protrusion from their mouth. This gives the false illusion that these frogs have teeth. Instead, they have an extra bone plate in their jaw that projects outwards and gives the appearance of teeth. These frogs have three toes on each foot. Each outside toe is almost equal in length but the middle toe is longer than the other two.

Bright skin coloration in P. terribilis is thought to be a warning to predators that they are poisonous. Their skin is saturated in an alkaloid poison that contains batrachotoxins. These toxins prevent nerves from transmitting nerve impulses and ultimately result in muscle paralysis. About 1900 micrograms of batrachotoxins can be found in these frogs. Only 2 to 200 micrograms is thought to be lethal to humans.

Adult females are typically larger than males. The average body length reaches 47 mm but females can reach 50 to 55 mm. Compared to the 175 species of dendrobatids, P. terribilis does not have a wide range of sizes. Other species can be as small as a human fingernail.

Range length: 47 to 55 mm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry ; poisonous

Sexual Dimorphism: female larger

Golden poison frogs are best known for their extremely potent poison. The toxins they produces are twenty times more powerful than any other poison dart frog toxin. Their brightly colored bodies warn predators of their extreme toxicity. This serves as the frog’s main anti-predator adaptation. The toxins produced are steroidal alkaloids batrachotoxin, homobatrachotoxin, and batrachotoxinin A. These compounds are extremely potent modulators of voltage-gated sodium channels. They keep the channels open and depolarize nerve and muscle cells irreversibly. This damaging action may lead to arrhythmias, fibrillation, and eventually cardiac failure. When accidentally transferred onto human facial skin, these toxins have been reported to cause a burning sensation lasting several hours.

There is only one known predator of P. terribilis: Liophis epinephelus. This is a small snake that feeds on young frogs. The snake is immune to the toxins produced by golden poison frogs but since it is so small, it can only feed on juvenile frogs.

Known Predators:

• Liophis epinephelus

Anti-predator Adaptations: aposematic

Golden poison frog males engage females in courtship by singing a long, melodious trill. This trill lasts 6 to 7 seconds followed by a 2 to 3 second version. The trill is usually a uniform train of notes uttered at a rate of 13 beats per second. The frequency for this tune is 1800Hz. This is a lower frequency when compared to related species of the family Dendrobatidae. They also communicate through gestures. A push up movement of the body represents dominance while the lowering of the head implies submission. A sign of excitement usually seen during hunting and courting includes the tapping of their long middle toe.

Communication Channels: visual ; acoustic

Perception Channels: visual ; tactile ; acoustic

In the wild golden poison frogs are believed to live up to 5 years or more. Due to their high toxicity levels, these frogs have few predators, contributing to their long lifespan. Lifespan in the wild has not been confirmed because these frogs have only been observed in captivity, where they have lived up to 5 years old.

Range lifespan
Status: captivity: 5 (high) years.

Typical lifespan
Status: captivity: 5 (high) years.

Golden poison frogs thrive in lowland Amazonian rainforests. This an extremely humid region that receives up to 5 m of rain per year and a minimum of 1.25 m. The region they inhabit is characterized by a hilly landscape, elevations varying from 100 to 200 m, and is covered by areas of wet gravel and small saplings and relatively little leafy debris. They are terrestrial animals that live on the forest floor, but they rely on freshwater to support their young.

Range elevation: 100 to 200 m.

Habitat Regions: tropical ; terrestrial

Terrestrial Biomes: rainforest

Aquatic Biomes: temporary pools

Phyllobates terribilis is found in the Amazonian rainforest along the Pacific coast of Colombia. Other members of the Family Dendrobatidae have been found in close proximity along the coast of South America into the southern part of Central America. Phyllobates terribilis population is concentrated along the upper Rio Saija drainage in the vicinity of Quebrada Guangui’ and at La Brea in Colombia. Geographically isolated populations exist along the east and west banks along this river, dividing the population. Overall P. terribilis has a limited range, but is abundant within that area.

Biogeographic Regions: neotropical (Native )

Golden poison frogs are insectivores and prey primarily on species of Brachymyrmex and Paratrechina ants. They also consume small invertebrates such as termites and beetles. Golden poison frogs use their long, sticky tongues to capture prey. They stalk and attack prey in one quick movement; this movement is so fast it's hard to see the mechanics of it with the naked eye. An adhesive tongue enables the prey to stick to its mouth to aid in capturing. Typically, they will not attack an insect bigger than a full grown cricket, approximately 1 inch. It has recently been discovered that feeding on a small Choresine beetle (Family Melyridae) may be the main source of toxicity for P. terribilis.

Animal Foods: insects; terrestrial non-insect arthropods; terrestrial worms

Primary Diet: carnivore (Insectivore , Vermivore)

Golden poison frogs have only one natural predator. They usually sit out in the open. When approached they do not try to hide, but rather further their distance from the thing that approaches it. They are generalist feeders, preying on all types of fruit flies, crickets, beetles, and termites. Recent research shows that these frogs may obtain some of their poison by eating a beetle that belongs to the family, Melyridae.

Golden poison frogs are the most highly toxic of all frogs. Colombian tribes, such as the Embre and Choco Indians, use poison secreted from the frogs’ skin to poison their blowgun darts. After heating darts over a fire, they are wiped over the frogs’ backs. Heat causes the back of the frog to moisten with poison which makes it easily accessible. Poisoned darts can stay lethal for up to two years. The toxin enables these tribes to catch small animals for food. These frogs are also being captured, bred, and sold as pets. This is possible because of their decrease in toxicity once held in captivity for a certain period of time. Medical research is also being done to see if these poisons can be developed into muscle relaxants, anesthetics, and heart stimulants. It is thought that it could even become a better anesthetic than morphine.

Positive Impacts: pet trade ; body parts are source of valuable material; source of medicine or drug ; research and education; controls pest population

Golden poison frogs do not display aggressive behavior towards humans. However, contact with their skin can prove fatal because of their extreme toxicity. This is not true of captive individuals, which tend to lose their toxicity in the absence of the wild prey that are the source of that toxin.

Negative Impacts: injures humans (poisonous )

Like most frogs, golden poison frogs go through complete metamorphosis. Eggs are laid in small clutches of less than 20 and carried on the backs of males to small pools of water, where they develop and metamorphose into froglets.

Development - Life Cycle: metamorphosis

Golden poison frog populations have been decreasing due to deforestation for agricultural purposes. They can be found in fewer than five areas. This species is listed as endangered according to the IUCN Red List of Threatened Species.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: endangered

Phyllobates terribilis is polygynandrous; both males and females have multiple mates. Courtship and egg laying have only been observed in captivity, with limited specimens. Each breeding involved two or more male frogs and one female. Males attract females by using a variety of high pitched calls. Mating could be described as a frantic frenzy where individuals move quickly around each other during egg laying. This is hard to observe because the movement is so fast and done under cover of vegetation. Specifics on mode of reproduction are unconfirmed but it is believed that there is some vent to vent contact between frogs during copulation. However, golden poison frog mating rituals have not been observed in their natural habitat. Golden poison frogs are thought to mate year round.

Mating System: polygynandrous (promiscuous)

Golden poison frog eggs have not been found in the wild. In captivity, clutches of eggs usually do not exceed 20. In captivity, once eggs are laid and fertilized in water (by captive carers) they hatch 11 to 12 days later, typically taking 2 to 4 days for all the eggs to be completely hatched. Not even 10 days after leaving the water, they begin to feed on Drosophila flies.

Breeding interval: Breeding intervals are unknown.

Breeding season: Golden poison frogs seem to breed year round.

Range number of offspring: 8 to 18.

Average number of offspring: 13-14.

Range time to hatching: 11 to 12 days.

Range time to independence: 55 to 60 days.

Range age at sexual or reproductive maturity (female): 12 to 18 months.

Average age at sexual or reproductive maturity (female): 13 months.

Range age at sexual or reproductive maturity (male): 12 to 18 months.

Average age at sexual or reproductive maturity (male): 13 months.

Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous

In the wild, once the female lays the eggs, the male fertilizes them and attaches them to its back. Only three male frogs have been captured with clutches of eggs on their backs. It seems that this period of carrying tadpoles on their backs is brief. It is a method of getting the eggs from their laying and fertilization site to the water to hatch. After fertilization and transfer to a small area of water for development, there is no further parental care.

Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Male)

The golden poison frog (Phyllobates terribilis), also known as the golden dart frog or golden poison arrow frog, is a poison dart frog endemic to the rainforests of Colombia. The golden poison frog has become endangered due to habitat destruction within its naturally limited range. Despite its small size, this frog is likely the most poisonous animal on the planet.