- For another species commonly known as the red-eyed treefrog, see Litoria chloris
|Red-eyed Treefrog range|
Agalychnis callidryas, known as the red-eyed treefrog, is an arboreal hylid native to Neotropical rainforests where it ranges from Mexico, through Central America, to Colombia. It is sometimes kept in captivity. The scientific name of the red-eyed treefrog, A. callidryas, comes from Greek words kalos (beautiful) and dryas (a tree or wood nymph).
The species has red eyes with vertically narrowed pupils. It has a vibrant green body with yellow and blue, vertically striped sides. Its webbed feet and toes are orange or red. The skin on the red-eyed treefrog's belly is soft and fragile, whereas the back is thicker and rougher. Red-eyed treefrogs have sticky pads on their toes.
Distribution and habitat
Red-eyed treefrogs inhabit areas near rivers and ponds in rainforests and humid lowlands on the Atlantic slopes from southern Veracruz and northern Oaxaca in Mexico, to central Panama and northern Colombia. They also live on the Pacific slope in southwestern Nicaragua and southwestern Costa Rica to eastern Panama. The optimum temperature for red-eyed treefrogs is 75–85 °F (24–29 °C) in the daytime, and 66–77 °F (19–25 °C) at night.
Phyllomedusine treefrogs are arboreal, meaning they spend a majority of their lives in trees; they are excellent jumpers. Red-eyed treefrogs are not poisonous and rely on camouflage to protect themselves. During the day, they remain motionless, cover their blue sides with their back legs, tuck their bright feet under their bellies, and shut their red eyes. Thus, they appear almost completely green, and well hidden among the foliage. The large red eyes serve as a defensive adaptation through deimatic behaviour. When a red-eyed treefrog detects an approaching predator, it abruptly opens its eyes and stares at the predator. The sudden appearance of the red eyes may startle the predator, giving the frog a chance to flee.
During the mating season, the male frogs shake the branches where they are sitting to improve their chances of finding a mate by keeping rivals at bay. This is the first evidence that tree-dwelling vertebrates use vibration to communicate. When rainfall is at its highest, a male red-eyed treefrog calls "chack" to get the attention of the female. During amplexus, the female carries the male on her back for several hours during the oviposition process. The female chooses a leaf above a pond or large puddle on which to lay her clutch of roughly 40 eggs. Since oviposition generally occurs on both sides of a leaf, red-eyed treefrogs may fold the leaf to hide the eggs from predators. They also produce sticky jelly to glue the eggs together; this may protect the eggs from splitting and dehydration.
The eggs develop into tadpoles, which hatch after six to seven days and fall into the water below. Red-eyed treefrog eggs hatch early (exhibiting phenotypic plasticity) when a change in the environment signals a danger to their survival. Dragonflies, fish, and water beetles prey on the tadpoles. The tadpoles remain in the water from three weeks to several months, until they metamorphose into frogs. The time of metamorphosis depends on duration of larval stage, which varies depending on environment. After metamorphosis, the color of tadpoles' torsos changes from green to brown, and their eyes, which are initially yellow, turn into deep red without much side patterning. These changes mark maturity. The lifespan of red-eyed treefrogs is about five years.
Young frogs that survive the first few weeks after metamorphosis move into the undergrowth and security of plants near their natal pools, often into the hollows of tubular plants such as bromeliads. Young frogs prey on very small flies and other insects during the first months of their lives. The young mature after two years and begin mating at the age of three to four years. These treefrogs are known to live up to five years (data from captive-breeding programs), depending on the health and conditions of their habitat (when aided by abundant plant growth, plenty of fresh water, and an abundance of small and larger insects on which to prey).
They sometimes breed successfully in captivity if kept in high-humidity vivaria (e.g., by using misting equipment), tropical plants such as Bromelia and other epiphyte plants, together with well-aerated water pools. Their captive habitat should have a light cycle with 11–12 hours of daylight and an average day temperature of 26–28 °C (and night-time averages of 22–35 °C). Simulating a rainy season once a year in November to December encourages reproduction.
Red-eyed treefrogs' embryos exhibit phenotypic plasticity, hatching early in response to disturbance to protect themselves. Though embryos are bred synchronously, they normally hatch after 6 to 10 days from oviposition without disturbance. However, a simultaneously early hatching in entire clutches is triggered when embryos are exposed to their predators or threatening environmental changes such as rainstorm and flood.
Predators are the major cause of this response. Since these frogs usually lay eggs on both the upper and the undersides of leaves above ponds, clutches need to protect themselves against arboreal, aerial and aquatic predators, such as snakes, dragonflies, fish, monkeys, and pathogenic fungi. When predators are close enough to produce detectable vibration, the embryos assess disturbance. After a few seconds, embryos vigorously hatch out into tadpoles and spread out to escape. Since eggs are usually laid above ponds, the response improves survival because tadpoles often fall into water on hatching. When tadpoles fall onto dry ground, they can survive up to 20 hours without water. However, vibration and disturbance caused by unthreatening environmental changes or other species do not induce early hatching.
The species is classified as Least Concern by the IUCN due to its wide distribution and presumed large populations; it is also present in a large number of protected areas throughout its range. Pressures on the red-eyed treefrog include habitat loss through deforestation, and some collection for the pet trade.
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