Australias Ancient Amphibian

Thought to have over 100 million years of independent evolution, the Tusked Frog (Adelotus brevis) is one of Australia’s truly unique amphibians. At first glance you may think it is just like every other frog, however when paying closer attention to the morphology of this frog, there are a few interesting features which set it a part from all other frog species. The most obvious feature is the tusks, hence its name the Tusked Frog. This frog species has small (around 5 mm long) tusks within the mouth on the lower jaw. Males use these tusks for ritual combat and territorial interactions during mating season.

 

A small male Tusked Frog (Adelotus brevis) | Copyright Chad Beranek (2014)

A small male Tusked Frog (Adelotus brevis) | Copyright Chad Beranek (2014)

 

This photo below shows the remarkable ancient characteristic of this frog species and is why this frog is call the Tusked Frog.

Adelotus brevis - Tusked frog

 

Generally speaking, the larger the head of the male, the more successful the male will be in combat. Head size is an easy way to tell a part males from female. Males always have a disproportionately larger and ‘boofier’ head than females , who seem to have a disproportionately smaller head! Males are usually bigger than females reaching a maximum of 5 cm snout to vent length, where females reach a maximum of 4 cm.

Another interesting feature of the Tusked Frog is the marbled belly which can have white, black and red patterns. Each individual has a unique belly pattern, and this can be used to tell each individual a part from one another.

 

Belly colouration of a large male | Copyright Chad Beranek (2014)

Belly colouration of a large male | Copyright Chad Beranek (2014)

 

This photo emphasizes the ‘boofy’ head of the males:

Tusked Frog (Adelotus brevis) - Male

 

Breeding season for the Tusked Frog takes place from October – December within slow moving streams and ponds, usually associated with rainforest or wet sclerophyll forest. They occur along the east coast of Australia, from north of Sydney to about the middle of the Queensland coast. Although they are not classified as threatened in Australia, these frogs have been suffering declines, especially in the New England Tableland. Reasons for their decline in these areas are due to habitat degradation and plague minnow, hence it is always a relief to hear these guys in a water way!

These guys can be quite hard to locate as they dive bomb the water as soon as there is a disturbance. It is easier to listen for their unique double inflection call (see below). Next time you find yourself near rainforest waters, see if you can listen out for this call, and be blessed by the knowledge that you are listening to a very ancient amphibian!