Australian Region's Unique Vertebrate Fauna

SYED MUHAMMAD KHAN (BS HONS. ZOOLOGY)
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Australian (Zoogeographical) Region
The Australian region (also referred to as the Australasian region) includes the whole
of Australia, New Guinea, Tasmania, a few of the smaller islands of the Indonesian
Archipelago, New Zealand, and other Pacific Islands. Australian and Neotropical
regions are the regions that are present in the Southern hemisphere, hence they were
grouped as a super-region: Notogaea (which comprises of the southern half of the
world’s zoogeographical realms).
Figure: Australian region (highlighted orange).
Sub-regions: The Australian region, like every other realm, has four sub-regions:
 Australian Sub-region: It includes Australia and Tasmania, it is located in the
Southern Pacific Ocean.
 Austro-Malayan Sub-region: This region includes the Malayan Archipelago islands,
New Guinea, Solomon Islands, etc.

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 Polynesian Sub-region: Polynesia is a group of more than 1,000 islands scattered
over the central and southern Pacific Ocean (to the east of mainland Australia).
 New Zealand Sub-region: It is a group of ancient islands, situated to the south-east
of mainland Australia.
Boundaries: It is the only region that does not have any land connections whatsoever
with the world, although it is linked with the Oriental region via the Malayan archipelago
(which is a chain of islands extending between these two regions). It has the following
boundaries:
 Pacific Ocean: Eastern boundary (including Northeast and Southeast).
 Indian Ocean: Western boundary (including Northwest and Southwest).
 Wallacea: This transitional zone (which lies in the Malayan Archipelago) separates
the Australian and Oriental regions.
Climate: The northern section of Australia has a more tropical climate, hot and humid
in the summer, and quite warm and dry in the winter, while the southern parts are
cooler with mild summers and cool, sometimes rainy winters. The seasons are the
opposite of those in the Northern Hemisphere-when it's summer in the north, it’s winter
south of the equator. December and January are the hottest months in Australia, July,
and August the coldest. Tasmania has a cool temperate climate with four distinct
seasons. New Zealand's climate is complex and varies from warm subtropical in the
far north to cool temperate climates in the far south, with severe alpine conditions in
the mountainous areas. The climate of New Guinea is tropical.
Biomes: The most dominant biomes of Australia are deserts and arid planes, which
are found in its interior. Forests are present in the northern, eastern, and southern
regions. Grasslands are also present. Most of New Zealand’s biomes are temperate
forests. But it is also partly composed of shrublands, temperate grasslands, and
savannas. Tasmania is mostly composed of temperate forests, while New Guinea
contains tropical forests.

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Figure: Biomes of mainland Australia.
Figures: Some biomes of the Australian region (top left to bottom right) – desert,
temperate rainforest, tropical rainforest, swamp, and snow-covered mountains.

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Vertebrate Fauna of the Australian Region
The Australian region has a huge number of endemic animal species, i.e. they are not
found anywhere else in the world. Most of this endemic fauna is very primitive in
comparison to that of the rest of the world, hence this region is also referred to as the
“veritable museum of archaic animals”. The details of its unique and symbolic
vertebrate fauna are as follows:
1. Freshwater Fish
Freshwater fish fauna is primitive, the Queensland Lungfish (Neoceratodus frosteri)
and osteoglossids (Arowana) are unique fish species of the Australian region. A lot of
other species such as bass, perches, catfish, etc. are also found here. For its land-
size, Australia has a low diversity of native freshwater fish with only 280 described
species. This is largely because Australia is a very dry continent with sporadic rainfall
and large areas of desert. The details of some notable species are as follows:
Queensland Lungfish: The Queensland lungfish (Neoceratodus frosteri) is one of only
six extant lungfish species (four species of the genus Protopterus, one species of the
genus Lepidosiren and one species of the genus Neoceratodus) in the world. Endemic
to Australia, Neoceratodus has remained virtually unchanged for well over 100 million
years, making it a living fossil and one of the oldest living vertebrate genera on the
planet. It inhabits mud, sand, or gravel bottoms. It is a sluggish species that prefers
still or slow-flowing waters, usually in deep pools. During a period of drought, it can
tolerate stagnant conditions by breathing air, surfacing 1–2 times per hour. The
Queensland lungfish can live for several days out of the water, if it is kept moist, but
will not survive total water depletion, unlike its African counterparts; it is a facultative
air-breather that will die if forced to depend on air-breathing. It is nocturnally active
and feeds on frogs, tadpoles, fishes, shrimp, earthworms, snails, aquatic plants, and
native fruits fallen from trees overhanging the creeks. It browses among the detritus,
using its electroreceptors to pick up hidden mollusks, worms or crustaceans.

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Figure: Queensland Lungfish (Neoceratodus frosteri).
Arowanas (Osteoglossids): Arowanas are freshwater bony fish of the family
Osteoglossidae, also known as bony tongues. The name “bony-tongues” is derived
from a toothed bone on the floor of the mouth, the “tongue”, equipped with teeth that
bite against teeth on the roof of the mouth. The Arowana is a facultative air breather
and can obtain oxygen from air by sucking it into its swim bladder, which is lined with
capillaries like lung tissue. Osteoglossids are carnivorous, often being specialized
surface feeders. They are excellent jumpers; they can leap more than 6 feet from the
water surface to pick off insects and birds from overhanging branches. Arowana
species typically grow to around 2 to 3 feet in captivity.
Figure: Australian Arowana (Scleropages jardinii).
Australian Bass: The Australian bass (Macquaria novemaculeata) is a small to medium-
sized, primarily freshwater (but estuarine spawning) species of fish found in coastal
rivers and streams along the east coast of Australia. Australian bass is an important

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member of the native fish assemblages found in east coast river systems. It is a
predatory native fish and an extremely popular angling species.
Figures: Australian Bass (Macquaria novemaculeata).
2. Amphibian Fauna
It is the only region where the common toad is not naturally found, although an invasive
species – the Cane Toad, was introduced. Frogs and tree frogs are present. Tailed
amphibians (newts and salamanders) and caecilians are absent. Some notable
species are:
Leaf Green Tree Frog: The leaf green tree frog (Litoria phyllochroa) is a species of
stream-dwelling frog, native to eastern Australia. This is a fairly small species of tree
frog, up to about 40 mm in length. It can be light green to dark olive green to light
brown to dark brown on the dorsal surface. The toes are three-quarters webbed and
toe discs are large. The belly is white.
Figures: Leaf Green Tree Frog (Litoria phyllochroa).
Cane Toad: The cane toad (Rhinella marina) is a large, terrestrial true toad native to
South and mainland Central America, but which has been introduced to various

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islands throughout Oceania and the Caribbean, as well as Northern Australia. It is the
world's largest toad. It has poison glands, and the tadpoles are highly toxic to most
animals if ingested. Its toxic skin can kill many animals, hence it has disturbed the
native ecology of Australia.
Figures: Cane toads (Rhinella marina), left – male & right – female.
3. Reptilian fauna
This region includes some exclusive families of reptiles such as: 1. Carettochelyidae
(pig-nosed turtles), 2. Pygopodidae (legless / flap-footed lizards) and 3.
Sphenodontidae (which has only one member – Tuatara, confined to New Zealand).
Lizards such as Varanus spp. (monitor lizards – most notably the Komodo dragon),
geckos and agamids are found here. Snake species include typhlops, pythons, cobras,
and elapids (among many others). Two species of crocodiles (the aggressive salt-
water and passive fresh-water crocodiles) are also present.
Tuatara: Tuatara (Sphenodon punctatus) is a reptile endemic to New Zealand.
Although resembling most lizards, they are part of the order Rhynchocephalia. Their
name derives from the Māori language (from Polynesia), and means “peaks on the
back”. The single species of tuatara is the only surviving member of its order, which
flourished around 200 million years ago. Tuatara are greenish-brown and grey, and
measure up to 80 cm (31 inches) from head to tail-tip and weigh up to 1.3 kg with a
spiny crest along the back, especially pronounced in males. They have two rows of
teeth in the upper jaw overlapping one row on the lower jaw, which is a very unique
feature among living tetrapods. They are also unusual in having a “third/parietal eye”

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(on the top of their head, it is distinctly visible when they are young), which is thought
to be involved in setting circadian and seasonal cycles. They can hear, although no
external ears are present. Tuataras are sometimes referred to as “living fossils”.
Figures: Tuatara (Sphenodon punctatus).
Komodo Dragon: The Komodo dragon (Varanus komodoensis) is a species of lizard
found in the Indonesian islands of Komodo, Rinca, Flores, and Gili Motang. It is the
largest living species of lizard, growing to a maximum length of 3 meters (10 feet) in
rare cases and weighing up to approximately 70 kilograms (150 lb). These lizards
dominate the ecosystems in which they live. Komodo dragons hunt and ambush prey
including invertebrates, birds, and mammals. The diet of big Komodo dragons mainly
consists of Timor deer, though they also eat considerable amounts of carrion
(decaying meat of dead animals). Komodo dragons also occasionally attack humans.
Figures: Komodo Dragon (Varanus komodoensis).
Burton’s Legless Lizard: Burton's legless lizard (Lialis burtonis) is a species of legless
lizard (also known as flap-footed lizard) in the family Pygopodidae. The species lacks

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forelegs and has only rudimentary hind legs. This species is endemic to Australia and
Papua New Guinea.
Figures: Burton’s Legless Lizard (Lialis burtonis).
Pig-nosed Turtle: The pig-nosed turtle (Carettochelys insculpta), also known as the
pitted-shelled turtle or Fly River turtle, is a species of turtle native to northern Australia
and southern New Guinea. The pig-nosed turtle is unlike any other species of
freshwater turtle. The feet are flippers, resembling those of marine turtles. The nose
looks like that of a pig, having the nostrils at the end of a fleshy snout, hence the
common name. The carapace is typically grey or olive, with a leathery texture, while
the plastron is cream-colored.
Figures: Pig-nosed Turtle (Carettochelys insculpta).
Diamond Python: Carpet python or diamond python (Morelia spilota), is a large (non-
venomous) constrictor snake of the family Pythonidae found in Australia, New Guinea,
Bismarck Archipelago, and the northern Solomon Islands. It is a large species of
python, reaching between 2 and 4 m (6.6 and 13.1 feet) in length and weighing up to

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15 kg (33 lb). Males are typically smaller than females. The head is triangular, the
coloring is highly variable, ranging from olive to black with white or cream and gold
markings. The patterning may be roughly diamond-shaped or have intricate markings
made up of light and dark bands on a background of gray or a version of brown.
Figures: Diamond / Carpet Python (Morelia spilota).
Saltwater Crocodile: The saltwater crocodile (Crocodylus porosus) is a crocodilian
populating the brackish and freshwater regions of eastern India, Southeast Asia, and
northern Australia. They are excellent swimmers and have often been spotted far out
at sea. It is among the largest crocodiles, it is an opportunistic hyper-carnivorous apex
predator. It ambushes most of its prey and then drowns or swallows it whole. It is
capable of prevailing over almost any animal that enters its territory, including other
apex predators such as sharks, varieties of freshwater and marine fish including
pelagic species, invertebrates such as crustaceans, various reptiles, birds, and
mammals (including humans).
Figures: Saltwater Crocodile (Crocodylus porosus).

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4. Avian Fauna
The Australian region is rich in its bird fauna. Parrots and pigeons are present. It is
famous for flightless birds like emus (Australia), cassowaries (New Guinea), and kiwi
(New Zealand). Kingfishers, honey-eaters, bowerbirds, and birds of paradise are also
common.
Emu: The emu (Dromaius novaehollandiae) is the second-largest living bird by height,
after its ratite (flightless birds without a keel on their sternum bone) relative, the ostrich.
It is endemic to Australia where it is the largest native bird. Emus are soft-feathered,
brown, flightless birds with long necks and legs, and can reach up to 1.9 meters (6.2
feet) in height. Emus can travel great distances, and when necessary can sprint at 50
km/h (31 mph); they forage for a variety of plants and insects, but have been known
to go for weeks without eating. They drink infrequently, but take in copious amounts
of water when the opportunity arises.
Figures: Emu (Dromaius novaehollandiae).
Cassowaries: Cassowaries (genus Casuarius) are ratites that are native to the tropical
forests of New Guinea, East Nusa Tenggara, the Maluku Islands, and northeastern
Australia. Cassowaries feed mainly on fruit, although all species are truly omnivorous
and will take a range of other plant food, including shoots and grass seeds, in addition
to fungi, invertebrates, and small vertebrates. Cassowaries are very wary of humans,
but if provoked they are capable of inflicting serious injuries, occasionally fatal, to dogs
and people. It is often referred to as “the world's most dangerous bird”.

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Figure: Cassowary (Casuarius spp.), left – adult & right – juvenile.
Kiwi: Kiwis are flightless birds native to New Zealand (genus Apteryx). Approximately
the size of a domestic chicken, kiwi is by far the smallest living ratites. The kiwi's egg
is one of the largest in proportion to body size (up to 20% of the female's weight) of
any species of bird in the world. Other unique adaptations of kiwi, such as their hair-
like feathers, short and stout legs, and using their nostrils at the end of their long beak
to detect prey before they even see it, have helped the bird to become internationally
well-known.
Figures: Kiwis – different species (Apteryx spp.)
Regent Honey-eater: The regent honeyeater (Anthochaera phrygia) is Australia’s most
threatened songbird. It has a black head, neck and upper breast, a yellow back and
breast scaled black, with the underparts grading into a white rump; black wings with
conspicuous yellow patches, and a black tail, edged yellow. Regent honeyeaters

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exploit flowering events to feed on a select number of Eucalyptus species. The birds
nest during the Austral spring/summer and can form small breeding aggregations
where habitat conditions are suitable. They are territorial and aggressively defend their
nesting area.
Figure: Regent Honey-eater (Anthochaera phrygia).
Bowerbirds: Bowerbirds make up the bird family Ptilonorhynchidae. They are renowned
for their unique courtship behavior, where males build a structure and decorate it with
sticks and brightly colored objects in an attempt to attract a mate. These are medium
to large-sized passerines, their diet consists mainly of fruit but may also include insects
(especially for nestlings), flowers, nectar, and leaves in some species. Ten species of
bowerbirds are endemic to New Guinea and eight are endemic to Australia, while two
are found in both. They occupy a range of different habitats, including rainforest,
eucalyptus and acacia forest, and shrublands.
Figures: Left to right – Golden bowerbird, Great bowerbird, and Tan-capped catbird.

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5. Mammalian Fauna
Australian region is famous for its primitive mammals. Placental mammals are absent,
except for those which were later introduced by man. Egg-laying mammals (Subclass
Prototheria) have one order – Monotremata (monos – “single” and trema – “hole”,
referring to the cloaca), of which two families: 1. Tachyglossidae (Echidna – spiny
anteaters) and 2. Ornithorhynchidae (Ornithorhynchus anatinus – Platypus) are
present in this region. The Australian region is also the real home of marsupials,
although they are also found in the Americas (North, Central, and South), i.e.
opossums. The basic character of marsupial mammals is the presence of a
pouch/marsupium in females where the babies are carried and nourished by a duct
from the mammary glands. Examples of marsupials include kangaroos, wallabies,
thylacines, koalas, etc.
Duck-billed Platypus: The platypus (Ornithorhynchus anatinus), sometimes referred to
as the duck-billed platypus, is a semiaquatic egg-laying mammal endemic to eastern
Australia, including Tasmania. It is one of the five extant species of monotremes, the
only mammals that lay eggs instead of giving birth to live young. It senses prey through
electrolocation. It is one of the few species of venomous mammals, as the male
platypus has a spur (spike) on the hindfoot that delivers a venom capable of causing
severe pain to humans.
Figure: Duck-billed Platypus (Ornithorhynchus anatinus).
Echidnas – Spiny Ant-eaters: Echidnas (family Tacchyglossidae), sometimes known as
spiny anteaters, belong to the monotreme order of egg-laying mammals. The diet of
some species consists of ants and termites, but they are not closely related to the true

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anteaters of the Americas, along with sloths and armadillos. Echidnas live in Australia
and New Guinea. Echidnas evolved between 20 and 50 million years ago, descending
from a platypus-like monotreme. This ancestor was aquatic, but echidnas adapted to
life on land.
Figures: Left to right – Short-beaked Echidna, Western Long-beaked Echidna, and
Eastern Long-beaked Echidna.
Koala: The koala (Phascolarctos cinereus) is an arboreal herbivorous marsupial native
to Australia. It is easily recognizable by its stout, tailless body and large head with
round, fluffy ears and large, spoon-shaped nose. The koala has a body length of 60–
85 cm (24–33 in) and weighs 4–15 kg (9–33 lb). Pelage color ranges from silver grey
to chocolate brown. Koalas typically inhabit open eucalypt woodlands, and the leaves
of these trees make up most of their diet. Koalas are largely sedentary and sleep up
to 20 hours a day. They are asocial animals, and bonding exists only between mothers
and dependent offspring. Koalas give birth to underdeveloped young that crawl into
their mothers' pouches, where they stay for the first six to seven months of their lives.
Figures: Koala (Phascolarctos cinereus).

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Kangaroos: Kangaroos are marsupials from the family Macropodidae (macropods,
meaning “large foot”). In common use, the term is used to describe the largest species
from this family, especially those of the genus Macropus (smaller members of this
family are referred to as wallabies and wallaroos). Kangaroos are indigenous to
Australia. Kangaroos have large, powerful hind legs, large feet adapted for leaping, a
long muscular tail for balance, and a small head. Like most marsupials, female
kangaroos have a pouch called a marsupium in which joeys (young ones) complete
postnatal development.
Figures: Female kangaroo with her baby (left) and a kangaroo jumping (right).
Thylacine: The thylacine (Thylacinus cynocephalus), now extinct, is one of the largest
known carnivorous marsupials. The last known live animal was captured in 1933 in
Tasmania. It is commonly known as the Tasmanian tiger because of its striped lower
back, or the Tasmanian wolf because of its canid-like characteristics. It was native to
Tasmania, New Guinea, and the Australian mainland. The thylacine was relatively shy
and nocturnal, with the general appearance of a medium-to-large-size dog, except for
its stiff tail and abdominal pouch similar to a kangaroo, and dark transverse stripes
that radiated from the top of its back, reminiscent of a tiger. The thylacine was a
formidable apex predator. Because of convergent evolution, it displayed a form and
adaptations similar to the tiger and wolf of the Northern Hemisphere, even though not
related.

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Figure: Thylacine (Thylacinus cynocephalus), also known as the Tasmanian
wolf/tiger.
The Boundary Between Australian & Oriental (Indo-Malayan) Regions
The two main continents of the Australian and Oriental regions are separated by a
string of islands known as the Malayan Archipelago. Of these islands, the western
ones belong to the Oriental region while the eastern ones belong to the Australian
region. But the main problem is to decide where to adjust several other smaller islands
in between these larger ones. Several attempts were made to divide these islands
between the two neighboring realms, the three most important lines (imaginary) of
divisions proposed by various scientists are as follows:
1. Wallace’s Line
It is a faunal boundary line drawn in 1859 by the British naturalist Alfred Russel
Wallace and named by English biologist Thomas Henry Huxley, it separates the
Oriental region and Wallacea (a transitional zone between Asia and Australia). The
line runs through Indonesia, according to this line, Java, Borneo, Mindanao, and Bali
islands have been given to the Oriental region whereas Celebes, Sangi, Talaud,
Lombok, etc. have been given to the Australian region. Wallace noticed this clear
division during his travels through the East Indies in the 19th century.
2. Lydekker’s Line
In 1895, Richard Lydekker proposed the Lydekker's line, which separates Wallacea
(west) from Australia and New Guinea (east). It follows the edge of the continental

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shelf of New Guinea to Australia (continental shelf – area around the continent which
is submerged under shallow water). It is the easternmost proposed boundary.
3. Weber’s Line
In 1904, Max Carl Wilhelm Webber proposed the Webber’s line, which is a
hypothetical boundary that lies approximately along the continental shelf of Australia
and New Guinea. It is based on the molluscan and mammalian fauna of the islands, it
is eastwards from the Wallace’s line and is sometimes preferred over it.
4. Wallacea – Transitional Zone
The middle islands of the Malayan archipelago have been populated haphazardly by
migrations across the ocean from either side. The fauna of each island has evolved
into a unique assemblage that does not resemble that of the other islands or the two
regions. Hence instead of debating on the validity of either Wallace's or Webber's line,
both lines can be accepted and the area between them can be referred to as a
transitional zone (which acts as a boundary) between the two regions – Wallacea
(named in the honor of Alfred Russel Wallace).
Figure: A map showing Wallace's line, Webber's line, and Lydekker’s line. Wallacea
lies between Wallace’s and Webber’s lines.

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