Poison dart frog

Poison dart frog
	Juvenile Dendrobates tinctorius "Cobalt.
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Amphibia
Order:	Anura
Family:	Dendrobatidae; Cope, 1865
Genera
	Many, about 150+ species within 9 genera

Poison Dart Frog is the common name given to the group of frogs belonging to the family Dendrobatidae. This group of frogs has many common names including "poison arrow" frogs, "poison dart" frogs, or simply dart frogs.

Background

Dendrobatid frogs are a group of small, diurnal, and often brightly colored frogs native to Central and South America. These frogs received their common name from the numerous types of poisonous alkaloids found in the skin of many species, such as the most poisonous dart frog, Phyllobates terribilis, also known as the golden poison dart frog.

Poison dart frogs are popularly characterized by their brightly colored skin and small size. The skin color can range from bright orange and black to true blue, to yellow, blue, and black spots. However, members of the most species-rich genus in the family, Colostethus, are generally brown and cryptically colored.

Poison dart frogs are only found in three geographical regions: Central America, South America, and a few of the Hawaiian islands. The only species found in Hawaii, Dendrobates auratus, was introduced to the islands by man.

There are well over 100 different species of poison dart frogs, only a handful of which are actually toxic to animals and humans.

Poison dart frogs range in size from 1/2" to 2 1/2" long when fully grown. Size depends not only on age of the frog, but also the species. Dendrobates tinctorius is one of the larger species, reaching 2 1/2" in size. Smaller species, like Dendrobates imitator do not reach much more than an inch.

Toxicity

More than 100 toxins have been identified in the skin secretions of members of the Dendrobatidae family of frogs, especially Dendrobates and Phyllobates. Members of the genus Dendrobates (of which there are at least 44 known species) are also known as "poison dart" or "poison arrow" frogs. However, only frogs of the genus Phyllobates produce the extremely potent neurotoxin, batrachotoxin. Even a very tiny amount of the batrachotoxin found in the skins of Phyllobates terribilis and at least two other species of Phyllobates frogs - on the order of just 40 micrograms - can be fatal.

Certain tribes in South America, such as the Noanamá Chocó and Emberá Chocó indians of western Colombia, dip the tips of their hunting arrows or blowgun darts in the poison found on the skin of Phyllobates terribilis, but no other species are widely used for this purpose. The poison is generally collected by roasting the frogs over a fire.

When a wild animal is shot with a poison-tipped arrow, it will die within minutes from the neurotoxin, making additional shots unnecessary to kill it. Poison darts made from either fresh or fermented batrachotoxin are enough to drop monkeys and birds in their tracks. Nerve paralysis is almost instantaneous.

There is considerable evidence that toxicity in these frogs is derived from their diet: primarily ants, mites, and beetles. These toxins are passed from the arthropod to the frog, then sequestered in glands on the amphibian's skin. Frogs brought from the wild into captivity and fed a regular captive diet, usually fruit flies or pin-head (hatchling) crickets, eventually lose their toxicity.

Reproduction and Parental Care

The majority of members of this group of frogs that have been studied are characterized by unusual reproductive strategies for amphibians. In the genus Colostethus, the oldest evolutionary group, eggs are laid on the forest floor by the female following often elaborate courtship behaviors by the male. One parent (generally the male) guards eggs until they hatch, when the newly hatched tadpoles wriggle onto the back of either the male or female parent, who transports hatching tadpoles to flowing streams. In some members of the genus Dendrobates, tadpoles are carried to small pools of water isolated in treeholes or other phytotelmata. In a few species, females return repeatedly to these treeholes to feed the tadpoles unfertilized nutritive "nurse" eggs, which the tadpoles rely on as a major source of food. Parental behaviors of this sort are highly complex and quite rare among amphibians.

Poison Frogs in Captivity

In captivity, poison dart frogs typically have a lifespan of 5 to 12+ years, but few data exist for wild populations. Most species reach maturity around 1.5 to 2.5 years of age. The easiest way to determine the sex of a particular species of poison dart frog is by observation in the wild. Mature male frogs will usually make a mating call after eating or after a heavy misting of water. The sound is similar to that of a series of high-pitched "clicks". In juvenile frogs the sex can sometimes be determined by the profile of the amphibian. The backs of males usually slope down with less of a break than females. Females are usually rounder and show a bigger break.

In captivity, most species thrive where humidity is kept around 80-100% constantly and temperature hovers around 75-80 F degrees during the day and no lower than 60-65 F degrees at night.

Captive poison dart frogs are sometimes confused with Mantellas, a small colorful frog only found on the island of Madagascar. These two families of frogs are not closely related and Mantellas typically prefer cooler temperatures, are non-poisonous and usually smaller in size than the medium to large species of poison dart frogs.

Species

Blue jeans poison dart frog (Dendrobates pumilio)

Dentrobatid genera include the following:

Species of Poison dart frogs include the following:

Allobates femoralis

Aromobates nocturnus ("Skunk Frog")

Colostethus: ("Rocket Frogs")

Cryptophyllobates azureiventris

Dendrobates:

Epipedobates:

Mannophryne:

Minyobates:

Nephelobates:

Phyllobates:

Some species include a number of sub-species 'morphs'. Typically different morphs represent geographically separated populations of the same species in the wild, showing different coloration characteristics. For example, D. tinctorius includes at least a dozen color morphs, including "Surinam Cobalt", "Inferalanis", "Powder Blue", "Patricia", "Regina", "Giant Orange", and others; although a few varieties may be the result of cross-breeding by domestic owners, rather than 'true' morphs found in the wild.

External links

Golden Arrow - poison frog facts - Wild Animals Online encyclopedia