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Frogs |
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Frogs
There are more than 200 different types of frogs and toads inhabiting
Australia.
The Australian Capital Territory (ACT) is home to 18 of these. (refer
to the Frogs in Canberra page for information
on these.
Unfortunately 3 of these (the Green & Golden Bell Frog Litoria
aurea, the Warty Swamp Frog Litoria raniformis, and the Yellow-spotted
Tree Frog Litoria castanea) are believed to be locally extinct,
with more frogs declining in population over the last 20 years. Numerous
other species throughout Australia, have apparently disappeared completely
or their sightings have become very rare and many are threatened.
Why is the population of frogs and toads declining? There are many
theories -
- global warming,
- increasing ultraviolet radiation
- acid rain
- habitat loss and land degradation
- disease (infective fungus - Batrachochytrium dendrobatidis)
- pollution
- introduction of exotic animals (cane toad, fish, cats, dogs, etc)
- widespread use of pesticides and herbicides
The bottom line is that once there were lots of frogs and now there
are as many or in some cases none.
FROG FAMILIES IN AUSTRALIA
There are five frogs families in Australia. These species are the tree
frogs (Hylidae), southern frogs (Myobatrachidae / Leptodactylidae),
true frogs (Ranidae), narrow-mouthed frogs (Microhylidae) and the introduced
true toads (Bufonidae). The term frog and toad is a little confused
in Australia. Australia has only one toad - the introduced Cane Toad
(Bufo marinus). The popular usage of the word "toad"
or "toadlet" has been given to any slow, warty, terrestrial
frog, while anything that was active, smooth-skinned, climbed or jumped,
was popularly gioven the name "frog".
Below is a brief explaination of the Australian frog families.
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Green & Golden Bell Frog, Green & Golden Grass Frog
(Litoria aurea)
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FAMILY: HYLIDAE
Members of this family are commonly called Tree Frogs.
This is due to the development, in many species, or large fingers
and toes which enable them to climb. Some are truly tree frogs
while others are almost incapable of climbing. Australian Hylidae
vary enormously. Some are very agile arboreal species with large
adhesive discs on their fingers and toes, others are long limbed
terrestrial species with only slighly expanded discs. This family
is characterised by having the following feature:
- Arciferal pectoral girdle (the epicoracoid cartileages are
free and overlapping);
- Most have an intercalary cartilage between the last two bones
of each finger and toe, which gives the finger and toes a notched
look;
- The fingers and toe discs may be well or poorly developed;
- The sacral diapophyses is dilated; and
- Maxillary teeth are present.
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FAMILY: MYOBATRACHIDAE
These frogs are known as the Southern Frogs and are sometimes
placed in the Leptodactylidae family. Many are burrowers, some
are swamp dwellers, and one lives only above the snow-line. Most
are burrowing or terrestrial. This family is characterised by
having the following feature:
- Arciferal pectoral girdle (the epicoracoid cartileages are
free and overlapping);
- Intercalary cartilages are absent;
- The fingers and toe discs are small or absent, without lateral
grooves;
- Sacral diapophyses is more or less dilated;
- Has eight presacral vertebrae, the first two being fused in
some; and
- Maxillary teeth present, or if absent, the toes never more
than about half-webbed.
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Southern Barred Frog, Giant Barred Frog, Giant Barred River
Frog (Mixophyes iteratus)
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Slender Frog, Shrill Chirper Frog, Shrill Whistling-frog (Sphenophryne
gracilipes)
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FAMILY: MICROHYLIDAE
This is a large group of frogs that occur throughout the tropics.
They are confined to the wet rainforests of far north-western
Queensland and the monsoonal forests of Arnhem Land. All species
lay their eggs on the ground and they hatch fully formed from
the egg. Eggs are often guarded by the males. (Identification
of some species is often very difficuly.) This family is characterised
by having the following feature:
- Firmisternal pectoral girdle (the epicoracoid cartileages
are fused in the middle);
- The intercalary cartilage is absent;
- The finger and toe discs are present or absent, with lateral
grooves;
- The sacral diapophyses is dilated;
- Maxillary teeth usually absent;
- The toes are not webbed; and
- No dorso-lateral skin-fold.
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FAMILY: RANIDAE
Australia has only one of these so-called "True" frogs.
This frog is only found in the Cape York Peninsula. This family
is characterised by having the following feature:
- Firmisternal pectoral girdle (the epicoracoid cartileages
are fused in the middle);
- The intercalary cartilage is absent;
- Small finger and toe discs are present, with lateral grooves;
- The sacral diapophyses cylindrical;
- Maxillary teeth present;
- The toes are fully webbed; and
- A dorso-lateral skin-fold from eye to hindlimb.
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Water Frog, Australian Bullfrog (Rana daemeli)
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