by M. Terada
When it rains, this frog always cries. This phenomenon happens all over Japan. So Japanese tree frogs are very famous Japanese people love them. Japanese tree frog has many ordinary names. For example, “gyaku-gyaku-donku” in Kyusyu.
Japanese tree frog’s scientific name is Hyla japonica. This frog size is about 3~4cm. (Incidentally, the female is bigger than the male.) The color is usually a greenish-yellow (famous variant color is sky blue.) Occasionally, ther put on grayish brown of protective color. This color change phenomenon’s structure is pigment cell’s expansion and contraction (expansion and contraction’s reason is circumference environment, temperature, humidity and brightness.) The skin is covered with mucosa, but it has poison. This poison protects the frog from enemies. So we must wash hands after touching Japanese tree frog.
Range & Ecology
Most frogs live at water’s edge. But Japanese tree frog does not always live at water’s edge. They can live on the tree. So they often live in forest. They are active in spring, summer and fall, are go into hibernation in winter. They can live in city because they are resistant to dryness and good at stereo lively motion. But Japanese tree frog is less adaptive than Toad, they does not choose food size.
Japanese tree frog’s feeding habits are flesh-eating. They eat small insects and spiders. They do not eat dead body and motionless substance, because they react to movement. When they hunt, they hold prey and next moment they put the prey into gullet’s interior. They come to human habitation’s window and the front of vending machine’s light in night (because they can good of prey upon to crowd insect.)
Japanese tree frog’s natural enemy are birds (Ardeidae, Halcyon and the like.), snakes (Rhabdophis, Amphiesma and the like) and mammalian (weasel, tanuki and the like).
Rhacophorus schlegelii and Rhacophorus arboreus look like Japanese tree frog, but body size and color are a little different.
Japanese tree frog’s cry expression “gge gge gge gge ”. All crying frogs are male. Frog’s breeding season is mainly spring. Normal frogs cry in only breeding season’s night, but Japanese tree frog’s cry before rain. So they often cry in daytime.
Imagoes crowd in swarms in paddies and ponds in spring. At the time, male’s throat color change. Male mate with female. They spawn in surface of the water. Fertilized eggs twine around plant’s stem. Fertilized eggs hatch after 2~3 days. Larva’s color is brown. Larva has external gill, but it is not long before external into body. Japanese tree frog tadpole’s body color is brown. (Toad tadpole’s color is black.) Tadpole eat dead body of a living thing and algae. Japanese tree frog tadpole metamorphose after about one month.
Japanese tree frogs live all over Japan. If you would like to watch them, spring is the best time. But you must wash hands after touch Japanese tree frog. Don’t forget that they have poison.