Amero-Australian Treefrogs: Hylidae

Physical characteristics: The water-holding frog is a chubby frog that has a round but flattened body. Its head blends into its body and does not have an obvious neck. Its eyes sit toward the top of the head. Its legs are strong, but rather short, almost disappearing under the body when the frog is sitting still. Each hind foot has a bump, or tubercle, that is shaped like the edge of a shovel blade. The toes are webbed. The frog is dark brown, gray, or green with dark blotches on its back. It usually becomes greener in the mating season. Its underside is white. Females are the larger sex. Females grow to 2.0 to 2.9 inches (5.0 to 7.2 centimeters) in length, while males reach 1.7 to 2.6 inches (4.2 to 6.4 centimeters).

Geographic range: The water-holding frog lives in three parts of Australia: a large area of the far west, a small spot in the north, and a large area in the middle of the continent from the center to the east.

The water-holding frog inflates its flexible body full of water after floods on the arid floodplain of the Paroo River, Australia. As the water recedes, the frog will burrow underground and live on its stored water. (Photograph by Wayne Lawler. Photo Researchers, Inc.)

Habitat: It spends much of its life beneath the ground of deserts and dry grasslands. During the rainy season, males and females come to the surface to mate and have their young in new, small pools of water that have filled with the rain.

Diet: It eats various arthropods that it finds during the rainy season.

Behavior and reproduction: The weather for most of the year is very dry where this frog lives, and the frog survives by digging with its hind feet and tubercles and burrowing backward into the soil to bury itself. Once dug in, sometimes as much as 3.3 feet (1 meter) deep, it sheds a few layers of skin, which harden into a cocoon that keeps its body from drying out. The frog enters a deep resting stage, called estivation, and remains in that state until the rainy season begins. In some years, even the rainy season is not wet enough, and the frogs stay underground for the entire year to wait for the next heavy rains.

When the rains fall hard enough to make shallow pools on the ground, the frogs crawl out from underground. The males call with long, snore-like sounds. Females find the males and mate with them. Each female lays clumps of eggs—sometimes several hundred—in the pools. The eggs hatch into tadpoles, which must turn into frogs before the pools dry up. This can take as little as thirty days. As the rainy season ends, the frogs fill their bodies with water before digging back underground to wait for the next bout of wet weather.

Water-holding frogs and people: Native people, called Australian aborigines (ab-or-RIJ-ih-neez), live in the same area as the frogs. The people sometimes dig the animals from their underground burrows and squeeze them to get a sip of water out of the frog.

Conservation status: The water-holding frog is not considered threatened or endangered. ∎