User:Paigeberzinski/Glass frog

Camouflage

The evolutionary advantage of a partly clear skin and an opaque back was a mystery, as it did not seem to be effective as camouflage. It was found that the colour of the frog's body changed little against darker or lighter foliage, but the legs were more translucent and consequently changed in brightness. By resting with the translucent legs surrounding the body, the frog's edge appears softer, with less brightness gradient from the leaf to the legs and from the legs to the body, making the outline less noticeable. This camouflage phenomenon, in which the frog's edges are softened to match the relative brightness of its surroundings, is referred to as edge diffusion. Experiments with computer-generated images and gelatine models of opaque and translucent frogs found that the translucent frogs were less visible, and were attacked by birds significantly less often.

Characteristics

Glass frogs are generally small, ranging from 3–7.5 cm (1.2–3.0 in) in length. They appear light green in color over most of their bodies, except for the skin along the lower surface of the body and legs, which are transparent or translucent. The glass frog's transparent skin allows an external view of the viscera—the internal organs present in the body's main cavity—making it so observers can witness the frog's internal processes, such as the heart beating and pumping blood through its arteries. Patterning of glass frogs is varied amongst different species, while some appear as a uniform green color, others display spots that range from yellow to white, mimicking the coloration of their eggs.

Their digit tips are expanded, allowing them to climb, thus allowing most to live in elevated areas along forest streams, such as trees and shrubs.

Glass frogs are similar in appearance to some green frogs of the genus Eleutherodactylus and to some tree frogs of the family Hylidae. However, hylid tree frogs have eyes that face to the side, whilst those of glass frogs face forward.

Two members of the glass-frog family Centrolenidae (Centrolenella fleischmanni, C. prosoblepon) and the hylid subfamily Phyllomedusinae (Agalychnis moreletii, Pachymedusa dacnicolor) reflect near-infrared light (700 to 900 nanometers) when examined by infrared color photography. Infrared reflectance may confer adaptive advantage to these arboreal frogs both in thermoregulation and infrared cryptic coloration.

Lifecycle

Mating

Mating begins by the call of a male tree frog, who is perched either on the underside or top of a leaf over a lake edge or a stream. Once a female has responded to the male's call, mating begins on the leaf in the amplexus physical position, in which the male wraps his arms around the female and attaches himself to her back. Once the physical mating process has concluded, the female produces her eggs onto the leaf before departing, leaving the male to defend the newly-laid eggs against predators. Males will occasionally call for and mate with other females on the same leaf, establishing a multitude of different developmentally-staged egg clutches to guard.

Tadpoles

Once the tadpoles, the frog aquatic larval stage, have been hatched, they fall from their original position on the lead into the water below. When living in the water the tadpoles feed on the lead litter and streamside detritus until undergoing metamorphosis to become a froglet.

Conservation

Predators

A main predator towards the glass frog in its tadpole stage are "frog flies." The flies deposit their eggs within the frog eggs, and once having hatched, the maggots feed on the embryos of the glass frogs.