Wednesday, May 25, 2011

Poison Dart Frog Amazing tail Colour

Poison dart frogs wear some of the most brilliant and beautiful colors on Earth. Depending on their habitats, which are from the tropical forests of Costa Rica to Brazil, their coloring can be yellow, gold, copper, red, green, blue, or black. Their designs and colors scare off predators. You may have seen monkeys carrying their children on their backs. Well, some of these frogs show some of these parenting habits, including carrying both eggs and tadpoles on their backs. These frogs are some of the most toxic animals on Earth. The two-inch-long Golden Poison Dart Frog has enough venom to kill 10 grown men. Indigenous people of Colombia have used its powerful venom for centuries to tip their blowgun darts when hunting.


Scientists are not sure why these poison dart frogs are so poisonous, but it is possible they take in plant poisons which are carried by their prey, including ants, termites and beetles. Poison dart frogs raised in captivity and isolated from insects in their native habitat never develop venom. The medical research community has been exploring ways to use poison dart frog venom in medicine. Scientists have already used their venom to create a painkiller medicine.

Dyeing Poison Dart Frog

Strawberry Poison-Dart Frog

The Strawberry poison-dart frog, D. pumilio, is a tropical poison-dart frog found in the lowland Atlantic regions of Nicaragua, Costa Rica, and Panama (Reynolds et al, 2007). This anuran is a member of the family Dendrobatidae (Pröhl and Hödl, 1999) and a member of the pumilio group which contains two other dendrobatids; D. granuliferus and D. speciosus (Silverstone, 1975). The Dendrobatidae family contains approximately 170 described species and six genera, including Dendrobates (Claire et al, 2005). Some
anatomical characteristics include smooth or slightly granular skin, a round tympanum one-half the diameter of the eye, finger disks that are not sexually dimorphic, and a tarsal tubule that is only slightly developed if present at all (Silverstone, 1975).

Strawberry Poison-Dart Frog

D. pumilio inhabits lowland tropical wet forest zones and fruit plantations (Pröhl and Hödl, 1999) residing in microhabitats of fallen logs and bromeliads when in exposed areas (Silverstone, 1975). D. pumilio are terrestrial and diurnal frogs spending most of their time within 1 meter from the forest floor (Pröhl, 2002). Dendrobatids are active, diurnal foragers (Donnelly, 1991). Being terrestrial, the Strawberry poison-dart frog primarily feeds on small invertebrates which inhabit detritus material on the forest floor (Silverstone, 1975). Ants and mites which are available year round are the primary food source for D. pumilio. There are some dietary differences between adult Strawberry poison-dart frogs that could be a result of differences in behavior (Donnelly, 1991) which will be discussed in greater detail later in the paper.

Some physical characteristics include aposematic coloration, which, as in many other dendrobatids, serves as an effective signal to predators of their toxic skin alkaloids (Pröhl, 2002). There have been more than 80 alkaloids isolated from the skins of D. pumilio (Donnelly, 1989b). D. pumilio is unique regarding this aposematic coloration due to the fact that intraspecific differentiation in this frog is one of the most dramatic
cases of divergence among populations ever discovered (Summers et al, 1999); in regions of Panama, coloration can vary between the more common color of red or orange to blue, green, black, yellow and white and spotted and speckled patterns (Reynolds et al, 2007). There is usually only one color pattern in a given population (Silverstone, 1975).

GOLDEN Poison-Dart Frog

The throat coloration in males is usually darker than that of females and there are usually dark, black dots on the venter and dorsum (Silverstone, 1975). Like other Poison-dart frogs, D. pumilio exhibits elaborate social behavior; the species exhibits parental care and males are extremely territorial and aggressive (Donnelly, 1989a&b; Pröhl, 2002).

Reproduction and Parental Care

Among all of the anuran families, Poison-dart frogs are said to have the most elaborate social interactions (Donnelly, 1989a), which are seen most often during periods of mating. Mating is polygamous in D. pumilio; females and males mate several times with different mates during mating periods. This system of mating is associated with the tropical environment the frogs inhabit which prolongs availability of food, water and
other resources which allow females to continuously reproduce (Pröhl and Hödl, 1999). Courtship in D. pumilio takes approximately 10-98 minutes (Donnelly, 1989a) occurring on the forest floor during the day (Summers et al, 1999), usually in the morning (Pröhl and Hödl, 1999) and is initiated by the female who receptively approaches a calling male (Summers et al, 1999). The female will continue to approach the male and will often use tactile methods; she will stroke and nudge the male in approval (Reynolds et al, 2007; Summers et al, 1999).

Dyeing Poison Dart Frog

Encouraged by the female’s behavior, the male will continue to call and move away from her, eventually leading her to the oviposition site as she follows (Summers et al, 1999). Summers (1999) comments that females do not normally interact with other adults outside the context of courtship; D. pumilio is actually not a social species. Because D. pumilio is not a social species, Summers (1999) asserts that their
“courtship behavior provides an unambiguous assay of mate choice in this species”; when this frog does choose to interact with other frogs, it makes it easier to observe which frogs they prefer to associate with.

Once courtship has been initiated and the female has chosen the male, they deposit egg and sperm in a terrestrial moist location of the oviposition site while in a vent-to-vent contact (Donnelly, 1989a). Oviposition sites are usually in dense leaf litter on the forest floor (Donnelly, 1989a&b), which provides a moist microhabitat for the eggs to develop into tadpoles. Clutches are relatively small, averaging about 4.6 eggs per
clutch (Pröhl and Hödl, 1999). D. pumilio, like many Poison-dart frogs exhibit parental care from the male or the female in most species (Donnelly, 1989a). D. pumilio males attend to the eggs once they are fertilized (Donnelly, 1989a) by moistening them once a day (Pröhl, 2002), shedding water on them (Summers et al, 1997) until they develop into tadpoles, a process that takes approximately 10-14 days (Donnelly, 1989a). The males do not, however carry or feed the tadpoles (Summers et al, 1997) in their parental care.


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