Rare jewel-toned frogs shine at Mie aquarium

A trio of flashy frogs are competing for visitors' attention at the Toba Aquarium in Toba, Mie Prefecture.

The frogs, two in brilliant gold and one a cool sky blue, are rare and striking variations of the Japanese tree frog (Hyla japonica), a species commonly found across the nation.

A citizen spotted the 3-centimeter-long blue frog on a leaf of Japanese silver grass during a morning walk in Chofu, western Tokyo, and caught it at around 8 a.m. on June 30.

The person then contacted an acquaintance, a breeder at Toba Aquarium, who decided to take charge of the frog.

Most Japanese tree frogs are green, owing to the three layers of chromatophores, or cells containing pigments, between the dermis and epidermis. But chromatophore anomaly in at least one layer can produce individuals with blue or transparent skin, according to Toba Aquarium officials.

There are several reports of peculiarly colored tree frogs every year, and in the past, Toba Aquarium has displayed blue and transparent tree frogs caught in Mie Prefecture. The latest find, however, is something special.

"Many of the blue frogs have brown, mottled patterns," said Kana Horimoto, a public relations official at Toba Aquarium. "But an individual that is bright sky blue all over its body like this one is quite rare."

The breeder, on receiving the frog, cried out in admiration of its beauty, Horimoto said.

Sharing the spotlight at Toba Aquarium are two gold-colored Japanese tree frogs, about 2 cm in size. The frogs were grown from white tadpoles found in a rice paddy in the Isobe district of Shima, Mie Prefecture. Eight of the 13 white tadpoles, brought into the aquarium on June 1, grew into adulthood, the officials said.

While the breeders initially expected the tadpoles to grow into white frogs, their body colors are more of a yellow-gold. They are considered albinos, congenitally devoid of melanin pigments due to either recessive heredity or mutation, and have red eyes characteristic of such individuals.

Both of the dazzling hues have been popular with family visitors, and it's not hard to see why. With the bright gold seeming to reflect the nation's hopes for gold medals at the Olympic Games, and the cool sky blue offering a reprieve from the intense heat of summer, these rare gems seem custom-made for summer.

Visit the Toba Aquarium website at www.aquarium.co.jp/english/index.html for more information.