Poison frogs

(Dendrobatidae)

Class Amphibia

Order Anura

Family Dendrobatidae

Thumbnail description
Small, agile frogs that occur in rainforests of the New World tropics; more primitive genera are cryptically colored with nontoxic skin, whereas the derived genera are brightly colored poison frogs

Size
Most species are 0.75–1.5 in (15–35 mm) in length; a few species reach 2.5 in (62 mm)

Number of genera, species
9 genera; 207 species

Habitat
Rain and cloud forest

Conservation status
No species listed by the IUCN

Distribution
Southern Central America through tropical South America

Evolution and systematics

The relationship of the poison frog family to other frogs remains the subject of controversy. Dendrobatidae lies within a clade of frogs, the neobatrachians, that diverged in the early Cretaceous or late Jurassic. Within this clade, two major groups, the hyloids and ranoids, diverged. Since 1959 numerous studies have placed dendrobatids inconsistently within these two groups. Most recent studies have shown that placement within the hyloids, specifically the leptodactylid/bufonid clade, is most likely.

The largest dendrobatid genus, Colostethus, comprises about 100 species, whereas the more derived genera, including Dendrobates and Phyllobates, contain about 36 and five species, respectively. Relationships at the generic level are fairly well understood. In 1991 the most primitive dendrobatid known, Aromobates, was described. Colostethus and Mannophryne are basal or primitive groups closely related to Aromobates, whereas Dendrobates is the most derived, or advanced, genus.

Relationships of species within each genus are not well worked out. Partly this is because many species have small ranges and occur in areas that cannot be reached easily; thus, many species have not been studied in detail. The genus Phyllobates is best understood. This genus contains five species that occur from Colombia to southern Nicaragua and are united by being the only species that have a unique alkaloid (batrachotoxin) in the skin. Other genera, such as Colostethus and Epipedobates, may be composed of groups of species that are not related closely; thus, it is probable that these genera will be subdivided into smaller genera in the future. Many species in the poison frog family have yet to be discovered. At least three or four new species in this group are described each year. No subfamilies are recognized.

Physical characteristics

Poison frogs are typically small frogs, less than 1 in (2.5 mm) in body length. The name of one genus, Dendrobates, is derived from the Greek dendro (tree) and bates (walker), an allusion to the fact that they can walk or hop up trees. Dendrobatids have short but powerful hind limbs and are agile jumpers and, in some cases, climbers. They are characterized by the presence of divided scutes (thick pads of skin) on the upper surfaces of the fingers and toes.

Poison frogs derive their common name from the fact that the more derived, or advanced, frogs in the group are brightly colored and have toxic skin. All frogs have glands in the skin that produce a variety of noxious substances serving to protect them from predators. However, poison frogs are unique, because their skin glands contain a large array of alkaloids, which are especially toxic nitrogen-containing chemicals once believed to be produced only by plants. Investigations of these chemicals have found hundreds of different alkaloids in the four derived genera of dendrobatids. Individual species or populations of frogs have different alkaloids, and within a population individual frogs may have different combinations of alkaloids. Some of these alkaloids are encountered in only one or a few species of frogs, whereas others may be present in numerous species. Examples are batrachotoxin, found in only four of the five species of the genus Phyllobates, and epibatidine, found in just one species in the genus Epipedobates. It was once thought that the frogs produced these chemicals, but it is now believed that they are obtained from the frogs' diet.

The derived poisonous species of dendrobatids are brightly colored. Some species of Dendrobates are bright yellow with black spots and black and blue legs, whereas others are a brilliant green with black markings. At least one species, Dendrobates pumilio, has numerous differently colored individuals throughout its range. Some populations are bright red, others are yellow with black spots, and still others are blue. The more primitive species, such as those in the genera Aromobates, Colostethus, and Mannophryne, are cryptically colored, generally brown frogs that lack alkaloids in their skin.

Distribution

Poison frogs occur in the neotropics from Nicaragua south through Costa Rica, Panama, and northern South America to southern Brazil and Bolivia. Within their range, most species are found only in undisturbed primary rainforest or cloud forest, although a few species occur in converted pastureland, cerrado (a savanna-like habitat) in southern Brazil, or cacao plantations in Central America.

No dendrobatids are known to be extinct at present, but many dendrobatids have small distributions within the over-all range of the family, so information on the status of these species is difficult to obtain. Some species seem to be on the verge of extinction (e.g., D. mysteriosus in the Cordillera del Condor of Peru), and others have not been seen in the wild for years and may be extinct (e.g., D. speciosus from Panama). Only one species, Dendrobates auratus, has become established outside its natural range. This species was introduced into Hawaii.

Habitat

Throughout the range, most species of dendrobatids occur in primary rainforest. The more primitive species, such as those in the genus Colostethus and Mannophryne, occur strictly in leaf litter on the forest floor. Frogs in the genus Dendrobates are partially or completely arboreal, depending on the species. For example, some species of Dendrobates, such as D. auratus, D. pumilio, and D. castaneoticus, largely inhabit the forest floor leaf litter but frequently climb trees and vines. Dendrobates vanzolinii, a species in western Brazil, lives in the lower canopy of the forest and avoids the forest floor. Other species, such as D. arboreus in Panama, seem to have an almost entirely arboreal existence.

Nearly all species of dendrobatids deposit eggs on land. Among the more primitive species, tadpoles are transported to small, slow-moving streams or pools on the forest floor. The more derived species transport their tadpoles to container habitats, such as bromeliads, tree holes, Heliconia bracts, Brazil nut capsules, or other types of small phytotelmata (water-holding plants). Although most of these container habitats are arboreal, some, such as Brazil nut capsules and other seed husks, are on the forest floor.

Behavior

All species of dendrobatids, except the most primitive, Aromobates, are diurnal. They tend to be most active in early morning at first light and in late afternoon, particularly on rainy days. Dendrobatids are also most active and conspicuous during the rainy season. Their collective range encompasses a large area of the neotropics, and consequently the rainy season in any one area may be longer or shorter or occur earlier or later in the year compared with other areas. Dendrobatids may be found during the dry season, but they are generally less active during this time.

Many species of dendrobatids seem to be territorial. Territoriality typically is associated with reproduction. In most species, males are territorial, and females are not. However, in several species of Colostethus females are territorial.

Feeding ecology and diet

Dendrobatids usually feed on tiny arthropods, ranging in average size from 0.03 to 0.07 in (0.8 to 1.7 mm) in length. Prey include ants, mites, small beetles, small flies, springtails, and tiny spiders, among others.

Evidence is accumulating that toxic dendrobatids obtain alkaloids from their diet. When frogs collected as tadpoles were raised under similar conditions and fed either leaf-litter arthropods or fruit flies, only those fed on arthropods developed alkaloids in the skin. Poison frogs fed fruit flies dusted with alkaloids have been shown to absorb those toxins from the diet and secrete them from the skin glands. Some species of ants have the same alkaloids as those in dendrobatid skin; thus, ants may be one of the main sources of alkaloids. Further work on species of dendrobatid frogs representing both primitive and derived clades showed that three derived species (which are also toxic) had diets consisting 50–73% of ants, whereas the diets of five nontoxic species contained only 6–16% ants. Thus, the diet of the derived, toxic, brightly colored dendrobatids is composed of a much higher percentage of ants than the primitive, cryptically colored, nontoxic species.

Reproductive biology

Dendrobatid frogs breed primarily during the rainy season. Males typically call intensely at first light for a period of several hours and then are quiet during midday, unless rainfall occurs. They may call again in late afternoon, especially on wet days. Like other frogs, each species has a unique call. Call characteristics are important in distinguishing closely related species that may be very similar in morphologic features.

All species of dendrobatids (with the possible exception of Aromobates nocturnus) deposit eggs on land. Depending on the species, eggs may be deposited on leaves in leaf litter on the forest floor, or they may be attached above the waterline to the inside of a tree hole or a bromeliad tank.

The eggs are attended by the male or female parent, depending on the species. When the eggs have developed into tadpoles, the transporting parent sits among the tadpoles in the nest, and they wiggle up the parent's leg and onto the back. The tadpoles are attached to the body of the parent by mucopolysacchrides, chemicals that dissolve easily in water. The parent frog then carries the tadpoles to a body of water, such as a small stream or pool or a bromeliad tank. The parent submerges the back half of its body in the water, and the tadpoles gradually dislodge and swim away, thus ending the period of parental care for most species. In some species, parents spend substantial amounts of time searching for suitable pools.

In terms of reproduction, differences exist between the primitive and the advanced dendrobatids and even within these groups. Among the primitive species, clutch size is larger, and all tadpoles are transported at once. In some species of Colostethus, for example, clutch size may be from 25 to 35 offspring. Clutch size in Dendrobates is much smaller, generally from three to six eggs. In these species, depending on aspects of the biology, each tadpole may be transported singly by the parent to a different aquatic site, usually a tree hole or some other type of phytotelmata.

Parental care is more complex in some species of Dendrobates. In at least one species, D. vanzolinii, males and females may remain together as pairs and care for their offspring together. Eggs are deposited on the inside of tiny tree holes or vine holes above the water level. After the tadpoles develop, the male parent carries each one to another tiny tree hole, in which it completes its development. About every five days, the male and female court, which appears to trigger ovulation in the female. However, instead of depositing fertilized eggs above the waterline, the pair returns to the site of their tadpole. The tadpole goes through a stereotypic movement in which the body stiffens and vibrates. The female parent appears to respond to this movement by the tadpole by backing into the water and depositing one or two unfertilized eggs for the tadpole to consume. This type of parental care presumably evolved in response to the lack of nutrients in the tree holes; the tadpoles are dependent on the nutritive eggs produced by the parent to survive.

In another species of Dendrobates, D. pumilio, the female rather than the male transports the tadpoles from the nest in the leaf litter to individual leaf axils that contain a tiny bit of water. The female then returns about every five days to deposit eggs for the tadpole to consume. Although the male parent appears not to be involved, as is the case for D. vanzolinii, there is some suggestion that the female seeks the calling male and remains near him for a period of time, possibly to stimulate ovulation.

Tadpoles of all species of dendrobatids, except those in Dendrobates, are typical herbivores that graze on algae and detritus. In contrast, those of Dendrobates are predaceous. This trait may have evolved in response to confinement of the tadpoles in small, unproductive habitats, where the ability to kill and eat small macroinvertebrates, such as mosquito larvae, would have been advantageous. In some species, tadpoles of Dendrobates readily kill and eat smaller tadpoles of the same and different species; thus, as discussed earlier, parent frogs in some species transport only one tadpole at a time and place it singly at an isolated site for development so that it will not be consumed by one of its larger siblings.

Conservation status

Most species of dendrobatid frogs occur in rainforest habitats that are vulnerable to deforestation. In addition, the extent of the distribution ranges of many species is unknown, because areas where they may occur are unexplored. These facts make determination of the conservation status difficult. In Ecuador five species of Colostethus and one species of Dendrobates are declining in numbers; all are Andean species that occur above 3,940 ft (1,200 m). At present, no species are cited as threatened on the IUCN Red List. In contrast, all species, except those in the genera Colostethus, Mannophryne, and Nephelobates, are listed on CITES Appendix II.

Significance to humans

Derived species of dendrobatids produce large numbers of alkaloids in the skin. The toxins in most species have not been studied thoroughly, and little is known about the potential pharmacological uses. An alkaloid produced by one species of Epipedobates is a painkiller 200 times more potent than morphine. Some Indian tribes in Colombia have used skin toxins of three species in the genus Phyllobates as poison for their blowgun darts; blowguns were used in hunting small game.

Species accounts

List of Species

Venezuelan skunk frog

Aromobates nocturnus

taxonomy

Aromobates nocturnus Myers Paolillo, and Daly, 1991, about 1.2 mi (2 km) airline east-southeast of Agua de Obispos, Trujillo, Venezuela.

other common names

None known.

physical characteristics

The Venezuelan skunk frog is large compared with other dendrobatids; females may reach 2.5 in (62 mm) in snout-vent length. This species derives its generic name from the production of a particularly noxious substance that has a skunklike odor but which has defied analysis. The substance is not toxic and is not an alkaloid, like the chemicals found in the skin of advanced dendrobatids, but the noxious odor, released by the frog upon being handled, is sufficient to protect it from predators.

distribution

The Venezuelan skunk frog is known only from the type locality in northwestern Venezuela.

habitat

This species occurs in small streams and rivulets in dense Andean cloud forest at an elevation of 7,382 ft (2,250 m).

behavior

The species is entirely nocturnal, in contrast to all other species of dendrobatids. Also in contrast to all other dendrobatids, the Venezuelan skunk frog is strictly aquatic, found only by small streams, usually sitting or swimming in water.

feeding ecology and diet

No information is available on the diet or feeding, but individuals sitting out at night readily took insects tossed to them. They probably feed strictly on small insects and arthropods, like most other frogs.

reproductive biology

Individuals have not been observed calling, and no information is available on reproduction.

conservation status

The range of this species probably is restricted to a small area; thus, disturbance of the area could have a severe impact on populations of these frogs.

significance to humans

This frog, discovered only in the early 1980s, is significant because of its basal position in the poison frog family. It may offer clues to the relationship of poison frogs to other families of frogs. Its discovery illustrates how much remains to be discovered about tropical frogs.

Blue-toed rocket frog

Colostethus caeruleodactylus

taxonomy

Colostethus caeruleodactylus Lima and Caldwell, 2001, about 25 mi (40 km) south of Manaus, Amazonas, Brazil.

other common names

None known.

physical characteristics

The snout-vent length is 0.60–0.67 in (15.4–17.4 mm) for females and 0.58–0.63 in (14.9–16.3 mm) for males. These small frogs are brown on the dorsum, with white chins and bellies. Males have sky-blue fingers and blue discs on the toes during the breeding season. Females have blue discs on the fingers and toes.

distribution

This species is known only from the type locality.

habitat

The frogs occur in leaf litter in an isolated patch of slightly disturbed lowland igapó (flooded) forest intersected with small hills and valleys. During the rainy season, rising rivers overflow into small streams in the valleys, creating a system of deep, interconnected, meandering pools. The frogs occur on the slopes above the streams, and their tadpoles develop in the seasonal pools that form in the streams.

behavior

Males are territorial, defending small areas of forest approximately 1,000 ft² (10 m²) in size. Short, loud encounter calls are produced by the resident male when an intruding male approaches.

feeding ecology and diet

This species feeds on a variety of small insects and other arthropods.

reproductive biology

Reproduction takes place during the rainy season, from January through April. Courtship lasts all of one day and part of the following morning, after which an average of 19 eggs are deposited in rolled or folded leaves on the forest floor. Males attend the clutches and transport all the developing tadpoles near the end of the rainy season, when igapó pools are at their maximum depth.

conservation status

This species is known only from the type locality. Should the forest in this area be removed, the species would become extinct. No special protection is provided the forest at present; it is under the control of private landowners.

significance to humans

None known.

Stephen's rocket frog

Colostethus stepheni

taxonomy

Colostethus stepheni Martins, 1989, proveniente da bica da vila residencial da Usina Hidroeléctrica de Balbin, Município de Presidente Figueiredo, Amazonas, Brazil.

other common names

None known.

physical characteristics

The snout-vent length is 0.66–0.70 in (17.0–18.0 mm) in females and 0.59–0.64 in (15.2–16.5 mm) in males. This small frog has a brown dorsum with a white oblique lateral stripe.

distribution

This species is known only from the region of the type locality.

habitat

Individuals occur in the leaf litter of lowland tropical forest.

behavior

Males produce three types of vocalizations: an advertisement call to attract females, an encounter call to signal that another male is invading the caller's territory, and a courtship call to communicate at close range, particularly with a gravid female.

feeding ecology and diet

This species feeds on tiny arthropods found in leaf litter.

reproductive biology

Males call during the rainy season, from November to April. Peak calling times are at dawn and dusk, although males may call anytime during the day before or after heavy rainfall. Unlike most other dendrobatids, tadpoles of this species develop entirely in small terrestrial nests in cuplike leaves on the forest floor. Clutch size varies from three to six eggs; males remain with the clutches and guard them from potential predators, such as small lizards or large spiders.

conservation status

Not listed by IUCN.

significance to humans

None known.

Green poison frog

Dendrobates auratus

taxonomy

Dendrobates auratus Girard, 1855, Taboga Island, Panama.

other common names

German: Goldbaumsteiger.

physical characteristics

The snout-vent length is 1.06–1.65 in (27.0–42.0 mm) in females and 0.98–1.56 in (25.0–39.5 mm) in males. This relatively large dendrobatid typically has calligraphic brilliant green markings on a black background. There is substantial variation among populations in both hue (ranging from white to blue-green) and especially pattern (from thick stripes to dots).

distribution

This species occurs from Nicaragua through Costa Rica and Panama to Colombia.

habitat

The green poison frog is found in lowland primary rainforest.

behavior

Males are territorial at high population densities but may not be at low population densities. Males attempt to attract and mate with many females and can care for offspring of several different females simultaneously. This behavior increases male reproductive success but imposes a cost on the survival probability of each offspring. Females do not defend territories, but some females guard particular males and will attack other females to prevent them from approaching their mates. This species provides an excellent example of sexual conflict.

feeding ecology and diet

Like other species of Dendrobates, this one feeds primarily on tiny ants and mites. Other prey include tiny beetles, flies, and springtails.

reproductive biology

Eggs are laid in leaf litter. The male visits the eggs periodically over the two weeks of development, shedding water on them, removing fungus, and rotating the eggs. The male then transports the tadpoles on his back, usually one at a time, to small pools of water, typically in tree holes.

conservation status

Not threatened.

significance to humans

This species is popular in the pet trade, and most individuals are raised in captivity.

Brazil nut poison frog

Dendrobates castaneoticus

taxonomy

Dendrobates castaneoticus Caldwell and Myers, 1990, near the Rio Xingu, Pará, Brazil.

other common names

None known.

physical characteristics

The snout-vent length is 0.83–0.88 in (21.5–22.7 mm) in females and 0.70–0.79 in (17.9–20.3) in males. The body is black with white spots; the arms and legs are black with brilliant orange spots.

distribution

This species is known from the type locality and two other localities within 155 mi (250 km) in Pará, Brazil.

habitat

This species is found in primary rainforest.

behavior

This species is diurnal and commonly is seen hopping through leaf litter or climbing vines and trees in the forest. One individual hopped straight up the trunk of a large tree and disappeared into the canopy.

feeding ecology and diet

Like other species of Dendrobates, this one feeds primarily on tiny ants and mites. Other prey include tiny beetles, flies, and springtails.

reproductive biology

Neither eggs nor calling males have been observed. During the rainy season, males transport tadpoles singly to fallen Brazil nut capsules on the forest floor.

conservation status

The extent of the range and the number of populations in this species are unknown. Like many species of dendrobatids, the size of the distribution range is small.

significance to humans

None known.

Harlequin poison frog

Dendrobates histrionicus

taxonomy

Dendrobates histrionicus Berthold, 1845, Pacific versant of northwestern Colombia, probably the upper Río San Juan drainage in the present-day Departamento Risaralda.

other common names

None known.

physical characteristics

The snout-vent length is 1.1–1.5 in (28.0–38.0 mm) in females and 0.95–1.5 in (24–38 mm) in males. This large dendrobatid has extensive variation in color and pattern among populations. The color is typically red with yellow and orange variants.

distribution

The species inhabits Chocó of western Colombia and northwestern Ecuador.

habitat

This species occurs in lowland rainforest.

behavior

Resident males establish small territories. They respond aggressively when the call of another male is played on a tape recorder near them.

feeding ecology and diet

This species feeds on small insects and arthropods, particularly ants and mites.

reproductive biology

If a female approaches a calling male, the male continues calling until the female begins to follow him. He leads the female under the leaf litter, where deposition of eggs occurs. After the eggs develop into tadpoles, the female transports them on her back to small pools of water in the axils of plants such as Heliconia, where the tadpoles undergo the remainder of their development. This species has female parental care, as in the strawberry poison frog, but unlike the strawberry poison frog, the male does not tend the eggs.

conservation status

Not threatened.

significance to humans

None known.

Imitating poison frog

Dendrobates imitator

taxonomy

Dendrobates imitator Schulte, 1986, Tarapoto, Peru.

other common names

German: Zweipunkt-Baumsteiger.

physical characteristics

The snout-vent length is 0.67–0.87 in (17.0–22.0 mm). This small dendrobatid has considerable variation in color but generally is black with yellow stripes on the dorsum.

distribution

This species is known from the eastern foothills of the Andes in Departamentos San Martín and Huánuco, Peru.

habitat

The imitating poison frog occurs below 3,300 ft (1,000 m) in primary rainforest.

behavior

Little is known of this frog's behavior.

feeding ecology and diet

Like other species of Dendrobates, this one feeds primarily on tiny ants and mites. Other prey include tiny beetles, flies, and springtails.

reproductive biology

Not known.

conservation status

Not threatened.

significance to humans

This species represents the only known example of mimetic radiation (in which different populations of a single species mimic different species) in amphibians. Three populations of this frog occur in sympatry with one of three other species of poison frogs, D. variabilis, D. ventrimaculatus, and D. fantasticus, none of which is related closely to the imitating poison frog. These three species differ dramatically with respect to color pattern. Each population of the imitating poison frog looks virtually identical to the species with which it occurs in sympatry. Molecular phylogenetic analysis has confirmed that the separate populations of imitating poison frog are all closely related members of a single species. The mimicry is likely to be Müllerian in nature, because all involved species are highly toxic.

Blue-bellied poison frog

Dendrobates minutus

taxonomy

Dendrobates minutus Shreve, 1935, Barro Colorado Island, Panama.

other common names

German: Zwergbaumsteiger.

physical characteristics

The snout-vent length is 0.47–0.61 in (12.0–15.5 mm) in females and 0.47–0.59 in (12.0–15.0 mm) in males. This tiny dendrobatid typically is bronze on the dorsum, with a black-and-white or black-and-blue marbled venter.

distribution

This species occurs on the Pacific coast from Panama to central Colombia.

habitat

Individuals are found in rainforest below 3,300 ft (1,000 m).

behavior

Adult males transport tadpoles on their backs to bromeliad tanks. Tadpoles are predaceous and feed on mosquito larvae.

feeding ecology and diet

Adults feed on small insects and other arthropods. Like other dendrobatids, this species is an active, diurnal forager.

reproductive biology

Males are territorial. Clutches of two eggs are laid in leaf litter. The male attends the eggs periodically and carries the tadpoles to small pools of water in the leaf axils of plants.

conservation status

Not threatened.

significance to humans

None known.

Strawberry poison frog

Dendrobates pumilio

taxonomy

Dendrobates pumilio O. Schmidt, 1857, between Bocas del Toro and Volcán Chiriqui, Panama.

other common names

German: Erdbeerfröschchen.

physical characteristics

The snout-vent length is 0.69–0.95 in (17.5–24.0 mm) in females and 0.71–0.95 in (18.0–24.0 mm) in males. This relatively small dendrobatid typically is red with blue legs, although populations from the Bocas del Toro archipelago in Panama are among the most variable on earth. Populations there vary in color from blue to green and from yellow to red or orange and have patterns with speckles, spots, stripes, or solid colors. Sexual dimorphism is absent, except that males typically have darker throats than females. Genetic and geologic analysis shows that these populations diverged from each other very recently.

distribution

This species occurs in Nicaragua, Costa Rica, and Panama.

habitat

This species generally inhabits rainforest but also frequently occurs in cacao and banana groves.

behavior

Males are territorial and incessantly produce a nonmusical chirp during the wet season. Field studies have shown that males with larger territories with more three-dimensional structures are more likely to attract mates, possibly because they can advertise more effectively. Mate-choice experiments in the laboratory suggest that females from the Bocas del Toro archipelago prefer to mate with males of the same color.

feeding ecology and diet

This species feeds primarily on tiny ants and mites.

reproductive biology

The small clutch (two to six eggs) is laid in leaf litter. The male visits the eggs periodically over the two weeks of development, shedding water on them, removing fungus, and rotating the eggs. Females transport tadpoles singly to small pools of water, typically those in the leaf axils of bromeliads or large leafy plants like Philodendron. Females return to the pool, on average, every five days for several months to deposit infertile eggs that tadpoles rely on for food in their nutrient-poor pools.

conservation status

Not threatened.

significance to humans

None known.

Brazilian poison frog

Dendrobates vanzolinii

taxonomy

Dendrobates vanzolinii Myers, 1982, Porto Walter on the Rio Juruá, Acre, Brazil.

other common names

None known.

physical characteristics

The snout-vent length is 0.67–0.77 in (17.4–19.9 mm) in females and 0.62–0.70 in (16.1–18.1 mm) in males. This small frog has black spots and bars on a bright yellow background and a pattern of blue mesh on the legs.

distribution

This frog is known from western Brazil in the state of Acre and the adjacent Amazonian region in Peru.

habitat

The species inhabits lowland rainforest. Individuals avoid leaf litter; instead, they inhabit small trees or shrubs in the lower canopy.

behavior

Males are territorial and interact vocally with males in adjacent territories to establish the limits of their territories.

feeding ecology and diet

Adults forage continually during the day. They feed on tiny insects and other arthropods, primarily ants and mites.

reproductive biology

Pairs of frogs remain together and care for their offspring. Small clutches of two to three eggs are deposited in tiny tree holes above the waterline, and tadpoles develop individually in these nutrient-poor habitats. Pairs undergo courtship about every five days, but instead of depositing fertilized eggs, the female deposits eggs in the water for the tadpoles to consume.

conservation status

Not threatened. As in many other species of dendrobatids, little is known about the extent of the distribution range. Continual deforestation in the area around Porto Walter, Brazil, has caused the demise of some populations in that area.

significance to humans

This species is unusual among frogs, in that pairs remain together to care for their offspring. Loss of this species would prevent gaining a better understanding of the evolution of this reproductive mode and those in closely related species.

Amazonian poison frog

Dendrobates ventrimaculatus

taxonomy

Dendrobates ventrimaculatus Shreve, 1935, Sarayacu, Ecuador.

other common names

None known.

physical characteristics

The snout-vent length is 0.59–0.85 in (15–21.5 mm) in females and 0.57–0.79 in (14.5–20.0 mm) in males. This relatively small dendrobatid typically has linear yellow stripes on a black background, with a bright blue mesh pattern on the legs and venter.

distribution

This species occurs in the Amazon lowlands in Ecuador, Peru, Colombia, Brazil, and French Guiana.

habitat

Individuals inhabit lowland forest, where they live in leaf litter and climb into the forest canopy.

behavior

These frogs are active during the day in rainforest. They frequently climb into the canopy to feed, court, and deposit eggs in small pools of water held in leaf axils.

feeding ecology and diet

These frogs are diurnal, active foragers. They consume small insects, primarily ants, and other arthropods.

reproductive biology

Eggs are deposited in the stem axils of such plants as Heliconia, near the surface of the water. The male parent transports tadpoles to new pools, or they may slide into the pool below. Cannibalism of small tadpoles by older conspecifics may occur.

conservation status

Not threatened.

significance to humans

None known.

Phantasmal poison frog

Epipedobates tricolor

taxonomy

Epipedobates tricolor Boulenger, 1899, Porvenir, Provincia Bolívar, Ecuador.

other common names

None known.

physical characteristics

The snout-vent length is 0.83–1.04 in (21.0–26.5 mm) in females and 0.75–0.97 in (19.0–24.5 mm) in males. This medium-size frog is dark brown to dull red, with wide yellow or whitish stripes along the sides and down the middle of the back.

distribution

This frog is known from southwestern Ecuador and northwestern Peru west of the Andes.

habitat

The species inhabits wet and dry habitats but generally occurs near streams in mountain valleys.

behavior

Little is known, except for reproductive behavior.

feeding ecology and diet

This species feeds on small insects and other arthropods.

reproductive biology

Cephalic amplexus, in which the male sits atop the female and clasps her with his forelimbs around her head, has been observed in captive individuals of this species. Large clutches of 15–40 terrestrial eggs are tended by the male. The male carries all the tadpoles at one time on his back to a stream or small pool, where the tadpoles complete their development.

conservation status

Not threatened.

significance to humans

The phantasmal poison frog has a toxin called epibatidine, an alkaloid that binds to nicotine receptors and acts as an analgesic (painkiller). Remarkably, this painkiller is 200 times more powerful than morphine. Although epibatidine itself is too toxic to use as a painkiller, its discovery led to the synthesis of other drugs that bind to the same receptors and are also highly effective painkillers without the toxic effects of epibatidine.

Trinidad poison frog

Mannophryne trinitatis

taxonomy

Mannophryne trinitatis Garman, 1888, Trinidad. Containing 10 species, the genus Mannophryne is composed of small frogs that have a throat collar.

other common names

None known.

physical characteristics

The snout-vent length is 0.85–1.00 in (22.0–26.0 mm) in females and 0.74–0.85 in (19.0–22.0 mm) in males. Females and males are brown on the dorsum. Females have a bright yellow throat with a black collar and a white venter, whereas males have a gray throat and a black collar.

distribution

The species occurs in Trinidad and northern Venezuela.

habitat

The frogs occur around large boulders in intermittent and permanent streams in mountain ranges. They may wander a short distance from the streams during rainy periods.

behavior

In contrast to other species of dendrobatids, females (but not males) are territorial. Their small territories are usually 11 ft² (1 m²) or less. Females defend their territories by sitting upright on top of a boulder and pulsating their bright yellow throats at intruders.

feeding ecology and diet

This species feeds on small insects and other arthropods.

reproductive biology

Courting males use a visual advertisement display in addition to calling, presumably so females will not mistake them for intruders. The visual displays include running forward and jumping up with the front feet off the ground and moving quickly side to side in a crablike motion. Small clutches of eggs are deposited in rock crevices or under leaf litter during the rainy season. Males attend the eggs and transport an average of eight tadpoles to small pools along the streams.

conservation status

Not threatened.

significance to humans

None known.

Golden dart-poison frog

Phyllobates terribilis

taxonomy

Phyllobates terribilis Myers Daly, and Malkin, 1978, Quebrada Guangui, Departamento Cauca, Colombia.

other common names

English: Golden poison frog; German: Schrecklicher Pfeilgiftfrosch, Goldener Giftfrosch.

physical characteristics

Females of this large, brilliant yellow dendrobatid are 1.59–1.83 in (40.3–46.5 mm) in length, and males are 1.47–1.76 in (37.3–44.6 mm).

distribution

The species is known from the region of the type locality in Cauca, Colombia.

habitat

Individuals are found in lowland rainforest.

behavior

This species is diurnal and terrestrial, like most other dendrobatids. It does not have arboreal tendencies, like many species of Dendrobates.

feeding ecology and diet

The golden dart-poison frog feeds on small insects and other arthropods.

reproductive biology

This species has male parental care similar to that of the green poison frog, although the type of pools used for tadpole deposition in nature is not known.

conservation status

This species is known only from the vicinity of the type locality. Thus, any disturbance of this area could threaten the existence of populations of this species.

significance to humans

This species is the most toxic amphibian and one of the most toxic animals on Earth. Its skin contains the alkaloid batrachotoxin, which is a potent neurotoxin, a type of toxin that affects the nervous system. A microscopic amount is lethal if it reaches the bloodstream. Batrachotoxin acts by forcing sodium channels to remain open. It has become an extremely useful tool for investigating the physiology of sodium channels. Recent research shows that this toxin also is found in certain species of birds from New Guinea and in a North American insect. The toxin probably is produced by plants, though this has not yet been confirmed. The golden dart-poison frog and two closely related species in the Chocó region of Colombia are the only frogs known to be used to make dart poison.

Resources

Books

Heselhaus, Ralf. Poison-Arrow Frogs: Their Natural History and Care in Captivity. London: Blandford, 1992.

Schulte, Rainer. Pfeilgiftfrösche, "Arteneil Peru." INIBICO, Waiblingen, 1999.

Walls, Jerry G. Poison Frogs of the Family Dendrobatidae: Jewels of the Rainforest. Neptune City, NJ: TFH Publications, 1994.

Periodicals

Caldwell, Janalee P. "The Evolution of Myrmecophagy and Its Correlates in Dendrobatid Frogs (Anura: Dendrobatidae)." Journal of Zoology, London 240 (1996): 75–101.

——. "Pair Bonding in the Spotted Poison Frog." Nature 385 (1997): 211.

Caldwell, Janalee P., and Maria Carmozina Araújo. "Cannibalistic Interactions Resulting from Indiscriminate Predatory Behavior in Tadpoles of Poison Frogs (Anura: Dendrobatidae)." Biotropica 30 (1998): 92–103.

Caldwell, Janalee P., and Verônica L. Oliveira. "Determinants of Biparental Care in the Spotted Poison Frog, Dendrobates vanzolinii (Anura: Dendrobatidae)." Copeia 1999 (1999): 565–575.

Clough, M., and Kyle Summers. "Phylogenetic Systematics and Biogeography of the Poison Frogs: Evidence from Mitochondrial DNA Sequences." Biological Journal of the Linnaean Society 70, no. 3 (2000): 515–540.

Daly, John W., H. Martin Garraffo, and Charles W. Myers. "The Origin of Frog Skin Alkaloids: An Enigma." Pharmaceutical News 4, no. 4 (1997): 9–14.

Daly, John W., Charles W. Myers, and Noel Whittaker. "Further Classification of Skin Alkaloids from Neotropical Poison Frogs (Dendrobatidae), with a General Survey of Toxic/Noxious Substances in the Amphibia." Toxicon 25, no. 10 (1987): 1023–1095.

Myers, Charles W., and John W. Daly. "Dart-Poison Frogs." Scientific American 248 (1983): 120–133.

Myers, Charles W., John W. Daly, and Borys Malkin. "A Dangerously Toxic New Frog (Phyllobates) Used by Embera Indians of Western Colombia, with Discussion of Blowgun Fabrication and Dart Poisoning." Bulletin of the American Museum Natural History 161 (1978): 307–366.

Myers, Charles W., Alfredo Paolillo O., and John W. Daly. "Discovery of a Malodorous and Nocturnal Frog in the Family Dendrobatidae: Phylogenetic Significance of a New Genus and Species from the Venezuelan Andes." American Museum Novitates 3002 (1991): 1–20.

Summers, Kyle, and W. Amos. "Behavioral, Ecological and Molecular Genetic Analyses of Reproductive Strategies in the Amazonian Dart-Poison Frog, Dendrobates ventrimaculatus." Behavioral Ecology 8 (1997): 260–267.

Summers, Kyle, E. Bermingham, L. Weigt, S. McCafferty, and L. Dahlstrom. "Phenotypic and Mitochondrial DNA Divergence in Three Species of Dart-Poison Frogs with Contrasting Parental Care Behavior." Journal of Heredity 88 (1997): 8–13.

Summers, Kyle, and M. Clough. "The Evolution of Coloration and Toxicity in the Poison Frog Family (Dendrobatidae)." Proceedings of the National Academy of Science U S A 98, no. 11 (2001): 6227–6232.

Symula, Rebecca, Rainer Schulte, and Kyle Summers. "Molecular Phylogenetic Evidence for a Mimetic Radiation in Peruvian Poison Frogs Supports a Müllerian Mimicry Hypothesis." Proceedings of the Royal Society of London B 268 (2001): 2415–2421.

Vences, M., J. Kosuch, S. Lötters, A. Widmer, J. Köhler, K. H. Jungfer, and M. Veith. "Phylogeny and Classification of Poison Frogs (Amphibia: Dendrobatidae), Based on Mitochondrial 16S and 12S Ribosomal RNA Gene Sequences." Molecular Phylogenetics and Evolution 15 (2000): 34–40.

Wells, K. D. "Behavioral Ecology and Social Organization of a Dendrobatid Frog (Colostethus inguinalis)." Behavioral Ecology and Sociobiology 6 (1980): 199–209.

Weygoldt, P. "Evolution of Parental Care in Dart Poison Frogs (Amphibia: Dendrobatidae)." Zeitschrift für Zoologische Systematik und Evolutionsforschung 25 (1987): 51–67.

Janalee P. Caldwell, PhD

Kyle B. Summers, PhD