Many human mountain residents may have found the recent rain inconvenient, but the mountain’s frog population has thrived in the wet weather. The wet conditions provide an ideal living and breeding environment for frogs. Frogs have permeable skin, and to survive, must keep their skin moist, consequently they can be more active at night and during rain because there is minimum risk of their skin drying out. Frog choruses are particularly loud and varied on wet evenings because water provides an opportunity to breed, so male frogs call in an effort to attract females, and ward off rivals, and females may call back to males.
There are over 200 species of frog in Australia and most follow the usual breeding pattern – they lay eggs in a jelly like mass in the water, tadpoles hatch, they live and develop in the water, then they metamorphose into frogs and leave the water. However there are some frogs species that have developed far more unusual ways of reproducing.
Gastric-brooding Frogs also known as Platypus Frogs – two species of gastric brooding frog were discovered in Australia relatively recently, the Southern Gastric-brooding Frog (Rheobatrachus silus) was discovered in 1972 and the Northern Gastric-brooding Frog (Rheobatrachus vitellinus) was discovered in 1984. They were probably unobserved for so long because they were timid, aquatic frogs that spent much of their life submerged under water. Unfortunately both these species have not been observed for over 20 years and they are now presumed extinct. Their reproduction was unusual, the mother frog would swallow her young (it is not known if they were eggs or embryonic tadpoles at this stage). Once in the mother’s stomach, the young would produce hormones that would switch off the mother’s digestive secretions such as hydrochloric acid, and would also deactivate her upper intestine. The tadpoles developed by living off their yolk sac, as they grew, the mother’s stomach expanded until the tadpoles occupied most of the mother’s body cavity. After six to seven weeks the mother frog would give birth by opening her mouth wide and twenty to thirty fully formed froglets would emerge. The female’s digestive tract soon returned to normal and she could feed again within 4 days.
Pouched Frog also known as Hip Pocket Frog or Marsupial Frog (Assa darlingtoni) – is uncommon and found only in rainforests and Antarctic Beech forests on Lamington and adjacent ranges. To reproduce this frog does not require water. The female lays eggs on moist soil, the parents guard the eggs, after about two weeks the white finless tadpoles emerge. The father then climbs into the jelly that surrounded the eggs, this makes his skin very slippery and the tadpoles slide over his body and slither into skin pockets that are found on each side of his body. The tadpoles develop in the pouches while living off their yolk sac, after ten weeks they emerge as fully developed frogs.
Building a frog pond in your garden may help these amazing little creatures, because unfortunately many frog species appear to be declining rapidly.
- Written by Nadia O'Carroll