The Australian Green Frog, simply the Australian Green Frog, White Tree Frog, or Dumpy Tree Frog (Litoria caerulea) is a species of tree frog native to Australia and New Guinea, with introduced populations in New Zealand and USA. This species belongs to the genus Litoria. It is physiologically similar to several species in the genus, especially the Magnificent Tree Frog (Litoriavialida) and the Giant Tree Frog (Litoria Infrafrenata).
The green tree frog is a large species compared to most Australian frogs, reaching 10 cm in length. The average lifespan of frogs in captivity, about 16 years, is longer than most frogs. Green Tree Frogs are very docile and very suitable to live near human habitation. They are often found on windowsills or inside homes, feeding on insects exposed to light.
Due to their physical and behavioral traits, the Green Tree Frog has become one of the most recognizable frogs in the region and a popular exotic pet around the world. Frog skin secretions have antibacterial and antiviral properties that could prove useful in pharmaceutical preparations.
Source: The Animal King
Taxonomy
The common name of the species, “White’s Tree Frog”, is in honor of the first person to describe the species, John White. The Green Tree Frog was the first species of Australian frog to be scientifically classified. This species was originally called the “green frog” (Rana caerulea); Although the Green Tree Frog was green, the original White samples sent to the UK were damaged by preservatives and appeared blue. This is because the frog’s color is due to the blue and green pigments covered in a yellow layer. The preservative destroyed the yellow layer and left the frog green. The specific symbol, caerulea, which in Latin means blue, remains the same. The frog is also known simply as “Green Tree Frog”. However, that name is often given to the most common large tree frog in an area, such as the American tree frog (Hyla cinerea).
The Green Tree Frog is sometimes confused with the Magnificent Tree Frog (Litoriavialida), which is found only in north-west Australia and can be distinguished by the presence of large mammary glands and thymus on the head. The Giant Tree Frog (Litoria Infrafrenata) is also sometimes confused with the Green Tree Frog. The main difference is a clear white stripe along the edge of the Giant Tree Frog’s lower jaw, which is absent in the Green Tree Frog.
Allotment
The green tree frog is native to the northern and eastern regions of Australia and southern New Guinea. Distribution is limited to most areas with a humid tropical climate. Eastern Australia, although cool in winter, is also home to this species. It is found in the southern state of Victoria, but this frog cannot survive the cold winters of southern Victoria and is therefore restricted to the north. In New Guinea, the Green Tree Frog is restricted to the drier regions of the south. Its range stretches from Irian Jaya to Port Moresby, and is most abundant on Daru Island. There have been separate records from northern New Guinea, however this is thought to have been introduced by humans.
This species has been introduced to both the United States and New Zealand. In the United States, it is restricted to two areas within Florida, where it may be introduced through the pet trade. Only a small number of populations are found in Florida, and it is unclear whether they cause any ecological damage as an invasive species. In New Zealand, a population was once present; however, no one has seen since the 1950s.
Physical Description
Green tree frogs can grow up to 10 centimeters (4 inches) long. Its color depends on the temperature and color of the environment, from brown to green; ventral surface white. Frogs sometimes have small, white, irregularly shaped spots on their backs, up to 5 mm in diameter, increasing in number with age. Frogs have large discs at the ends of their toes, about 5 mm in diameter when fully grown. These give the frog a firm grip while climbing and allow them to climb upright on the glass. The eyes are yellow and have horizontal irises, typical of the genus Litoria. The fingers are about one-third webbed, and the toes are almost three-quarters webbed. The eardrum (the membrane of the skin similar to the eardrum) is visible.
The tadpole’s appearance changes throughout its development. The length of the species’ tadpoles ranges from 8.1 mm (once hatched) to 44 mm. They are initially brown-spotted, then hyperpigmented (to green or brown) as they develop. The underside begins to darken and then lighten, eventually turning white in adults. Eggs are brown, jelly-like and 1.1–1.4 mm in diameter.
Although frogs have lungs, they absorb oxygen through their skin and for this to work, the skin must be moist. One downside to moist skin is that pathogens can thrive on it, increasing the chance of infection. To combat this, frogs secrete peptides that kill these pathogens. Skin secretions from the Green Tree Frog contain caerins, a group of peptides with antibacterial and antiviral properties. It also contains caerulin, which has physiological effects similar to CCK-8, a digestive hormone and hunger suppressant. Several peptides from the skin secretions of the Green Tree Frog have been found to kill HIV without harming healthy T cells.
Ecosystem and behavior
The Green Tree Frog is very docile. They are nocturnal and emerge in the early evening to call (in spring and summer) and hunt at night. During the day, they seek out cool, dark and humid places to sleep. During the winter, the Green Tree Frog does not call and is usually not seen.
Depending on their location, Green Tree Frogs occupy different habitats. Usually, they are found in the canopy of trees near a source of still water. However, they can survive in swamps (among the reeds) or grasslands in cooler climates. Green Tree Frogs are well known for inhabiting indoor water sources, such as sinks or toilets. They can also be found on insectivorous windows. They will take up storage tanks (sumps), downpouts, and gutters, because they are high in humidity and are often cooler than the outside environment. Frogs are drawn to ducts and tanks during mating season, as immobilizers amplify their calls.
The name of this species is the low, slow, repetitive crawling turtle. During most of the year, they call from high places, such as trees and ditches. During the mating season, frogs descend, although still slightly above, and approach sources of still water, whether temporary or permanent. Like many other frogs, the Green Tree Frog doesn’t call just to attract a mate. Researchers have observed them call to advertise their location outside of the mating season, often after rain, for reasons the researchers are unsure of. They will make a nervous cry whenever they are in danger, such as when predators approach or when a person steps on a log inhabited by frogs.
The species’ diet consists mainly of insects and spiders, but may include smaller frogs and even small mammals. Frog teeth are not suitable for cutting prey, so the prey must fit inside the frog’s mouth. Many species of frogs push their sticky tongues into their prey. Prey is attached, and consumed. Green Tree Frog will use this technique on smaller prey; however, for larger prey, it pounces, then uses its hands to force the prey into its mouth.
This frog has few native predators, among them snakes and several species of lizards and birds. Since Europeans settled Australia, non-native carnivores have been introduced, mainly dogs and cats. These species have an average lifespan in captivity of 16 years, but some species have been known to live over 20 years, long for a frog. Life expectancy in the wild is lower than in captivity, due to predation.
Reproduction
Before mating season in late spring to summer, male Tree Frogs develop a black cushion on the inner surface of the thumb. This supports a diverse relationship by allowing the male to continue to cling to his mate for the duration of his existence. Males call (individually) to attract a female, and the two often meet at a still water source.
During skirmishes, males mount females. The female will then eject her eggs at a rate such that the sperm is forced into the egg. A large nest of about 200 to 300 eggs is left in the water, about half a meter away from the frog. Eggs sink and attach to submerged objects. Two frogs can stay together for about two days, this process is repeated many times, resulting in them laying an average of 2000 to 3000 eggs. An egg hatches three days after laying. The water must be at a temperature of 28–38 degrees Celsius and 5–50 cm deep for the eggs and tadpoles to survive. Metamorphosis takes two to three months, and sexual maturity about two years.
Storage status
Australian law grants protected status to the Green Tree Frogs – along with all Australian animals – under the federal Biodiversity Conservation and Environment Protection Act 1999. Much of the habitat is natural. The Green Tree Frog’s nature has been destroyed. In addition, some frogs have been found to be infected with the fungus chytrid (which causes chytridiomycosis). These two factors are linked to the overall decline of the frog population in Australia that threatens to reduce the population of the Green Tree Frog. However, because of the long lifespan of this species, any effects of reduced reproductive rates will be longer than those of shorter-lived species.
As a pet
The Green Tree Frog is one of the most popular pet frogs throughout the world. Its docile nature, often cartoon-like appearance, and long life expectancy make it an attractive choice for exotic-pet owners. It is also one of the easier frogs to care for: their diet is broad and they have a strong resistance to disease. One problem commonly associated with keeping this species as a pet is overfeeding; Green Tree Frogs tend to become obese if overfed. In the wild, exertion of energy is required for a frog to capture its prey. However, in captivity they are usually given live feed in a confined space. This lessens the activity needed for feeding, resulting in weight gain. An overweight member of the species will deposit fat layers over the top of the head and body, giving it a “dumpy” appearance.
