Australian Ground Frogs: Limnodynastidae

The species in this family are either nocturnal (nahk-TER-nuhl), which means that they are active mostly at night, or crepuscular (creh-PUS-kyuh-lur), which means that they come out only at dawn and dusk. As with the majority of other nocturnal or crepuscular frogs, the Australian ground frogs do not like air that is too dry, as it often is during the day. Instead, they come out when the air starts to become moister, which typically happens at night when the sun is down and the temperature starts to cool off. In addition, many Australian ground frogs will not even venture out at night during especially dry periods. For some of them, such dry periods, called droughts (drowts), happen at least once a year and may last several months. During this time, some of the Australian ground frogs burrow underground to keep from drying out.

Frogs must keep their skin moist to breathe. Like humans and other mammals, frogs can breathe through the nose and lungs. However, frogs also get a great deal of their oxygen right through the skin. If the skin dries out, they can no longer breathe through the skin, and they can suffocate. Many of the burrowing frogs in this family dig into the ground by swishing their powerful hind limbs one at a time and backing into the soil as their body wiggles back and forth. Other species, like Spencer's burrowing frog, dig backward into the soil, but turn their bodies in circles while they are doing it. These frogs look as if they are screwing themselves into the ground. Several species can stay underground for a number of months. They enter a sleep-like state, called estivation (es-tih-VAY-shun), and only wake up and become active again when the heavy spring rains drench the land. The tusked frog is an example. This animal, as well as numerous other members of this family, lives underground inside a cocoon of shed skin for several months each year.

Spring rains begin the mating season for most of the burrowing Australian ground frogs. In some of these species, all mating for the year is done within a few weeks' time. Some types of Australian ground frogs breed during certain seasons of the year, and others, like the spotted marsh frog, can mate and lay eggs all year long if the weather is right. Whenever their mating season begins, the males start calling at dusk or at night, usually from ponds, streams, or marshes, but sometimes from on land. Their calls attract females and also keep other males from invading their space. Different species have different calls. The spotted marsh frog, for instance, calls with a repeated clicking noise of "tik-tik-tik"; the giant burrowing frog sometimes goes by the name of eastern owl frog, because its call of "oo-oo-oo-oo-oo" sounds like an owl hooting; and the common spadefoot frog has a knocking trill for its call.

Some of the females in this family lay their jelly-coated eggs in the water, often in a foamy nest. The female typically makes the foam by flailing her feet and whipping up her eggs and the mucus surrounding them. This adds air to the mixture and creates the foam. The eggs hatch into tadpoles, which then swim out into the water, or in some cases, stay in the foam until they turn into froglets. Other females lay their eggs in a foam nest, but make it inside a burrow or among plant leaves and branches on shore. When heavy rains flood the nest, the eggs hatch into tadpoles, which then live in the water.