There are more lizards in Australia than anywhere else in the world, with representatives of five families. There are 114 species in 18 genera of gecko found throughout the Australian continent. The Pygopodidae is a family of limbless lizards endemic to the Australian region; of the 34 species from eight genera, only one species does not occur in Australia.

The Agamidae or Dragon lizards are represented by 66 species in 13 genera, including the Thorny Devil, Bearded Dragon and Frill-necked Lizard. There are 26 species of monitor lizard, family Varanidae, in Australia, where they are commonly known as goannas. The largest Australian monitor is the Perentie, which can reach up to 2 m in length. There are 389 species of skink from 38 genera, comprising about 50% of the total Australian lizard fauna; this group includes the blue-tongued lizards.

Fish

More than 4400 species of fish inhabit Australia’s waterways;[7] of these, 90% are endemic. However, due to the relative scarcity of freshwater waterways, Australia has only 170 species of freshwater fish. Two families of freshwater fish have ancient origins: the Arowana or “bony tongues,” and the Queensland Lungfish. The Queensland Lungfish is the most primitive of the lungfish, having evolved before Australia separated from Gondwana. One of the smallest freshwater fish, peculiar to the south-west of Western Australia, is the Salamanderfish, which can survive desiccation in the dry season by burrowing into mud. Other families with a potentially Gondwanan origin include the Retropinnidae, Galaxiidae, Aplochitonidae and Percichthyidae.

Apart from the ancient freshwater species, 70% of Australia’s freshwater fish have affinities with tropical Indo-Pacific marine species that have adapted to freshwater.[8] Nevertheless, fossil evidence indicates that many of these freshwater species are still ancient in origin. These species include freshwater lampreys, herrings, catfish, rainbowfish, and some 50 species of gudgeon, including the Sleepy Cod. Native freshwater game fish include the Barramundi, Murray Cod, and Golden Perch. Two species of endangered freshwater shark are found in the Northern Territory.

A number of exotic freshwater fish species, including Brown, Brook and Rainbow Trout, Atlantic and Chinook Salmon, Redfin Perch, Carp and Mosquitofish, have been introduced to Australian waterways.[9] The Mosquitofish is a particularly aggressive species known for harassing and nipping the fins of other fish. It has been linked to declines and localised extinctions of a number of small native fish species.

The introduced trout species have had serious negative impacts on a number of upland native fish species including Trout Cod, Macquarie Perch and Galaxias species as well as other upland fauna such as the Spotted Tree Frog. The Carp is strongly implicated in the dramatic loss in waterweed and permanently elevated levels of turbidity in the Murray-Darling Basin of southwest Australia.

Most of Australia’s fish species are marine. Groups of interest include the Moray eels and squirrelfish, as well as the pipefish and seahorses, whose males incubate their partner’s eggs in a specialised pouch. There are 80 species of grouper in Australian waters, including one of the world’s biggest bony fish, the Giant Grouper, which can grow as large as 2.7 m and weigh up to 400 kg. The trevally, a group of 50 species of silver schooling fish, and the snappers are popular species for commercial fishing.

The Great Barrier Reef supports a huge variety of small- and medium-sized reef fish, including the damselfish, butterflyfish, angelfish, gobies, cardinalfish, wrasse, triggerfish and surgeonfish. There are a number of venomous fish, among them several species of stonefish and pufferfish and the Red Lionfish, all of which have toxins that can kill humans. There are 11 venomous species of stingray, the largest of which is the Smooth Stingray. The barracudas are one of the reef’s largest species. However, large reef fish should not be eaten for fear of ciguatera poisoning.

Sharks inhabit all the coastal waters and estuarine habitats of Australia’s coast. There are 166 species, including 30 species of requiem shark, 32 of catshark, six of wobbegong shark, and 40 of dogfish shark. There are three species from the family Heterodontidae: the Port Jackson Shark, the Zebra Horn Shark and the Crested Horn Shark. In 2004, there were 12 unprovoked shark attacks in Australia, of which two were fatal.[10] Only 3 species of shark pose a significant threat to humans: the Bull shark, the Tiger Shark and the Great White Shark.

Some popular beaches in Queensland and New South Wales are protected by shark netting, a method that has reduced the population of both dangerous and harmless shark species through accidental entanglement. The overfishing of sharks has also significantly reduced shark numbers in Australian waters, and several species are now endangered. A Megamouth Shark was found on a Perth beach in 1988; very little is known about this species, but this discovery may indicate the presence of the species in Australian coastal waters.

Invertebrates

Of the estimated 200,000 animal species in Australia, about 96% are invertebrates. While the full extent of invertebrate diversity is uncertain, 90% of insects and molluscs are considered endemic. [1] Invertebrates occupy many ecological niches and are important in all ecosystems as decomposers, pollinators, and food sources. The largest group of invertebrates is the insects, comprising 75% of Australia’s known species of animals.

The most diverse insect orders are the Coleoptera, with 28,200 species of beetles and weevils, the Lepidoptera with 20,816 species including butterflies and moths, and 12,781 species of Hymenoptera, including the ants, bees and wasps. Order Diptera, which includes the flies and mosquitoes, comprises 7,786 species, Order Hemiptera, including bugs, aphids and hoppers, comprises 5,650 species; and there are 2,827 species of order Orthoptera, including grasshoppers, crickets and katydids.[11] Introduced species that pose a significant threat to native species include the European Wasp, the Red Fire Ant, the Yellow Crazy Ant and feral honeybees which compete with native bees.

Australia has a wide variety of arachnids, including 135 species of spider that are familiar enough to have common names. There are a number of highly venomous species, including the notorious Sydney Funnel-web and Red-back spiders, whose bites can be deadly. There are thousands of species of mites and ticks from order Acarina. Australia also has eight species of pseudoscorpion and nine scorpion species.

In the subclass Oligochaeta there are many families of aquatic worms, but only two families of native terrestrial worms: the Enchytraeidae, and the Megascolecidae. The latter includes the world’s largest earthworm, the Giant Gippsland Earthworm, found only in Gippsland, Victoria. On average they reach 80 cm in length, but specimens up to 3.7 m in length have been found.

The large family Parastacidae includes 124 species of Australian freshwater crayfish. These include the world’s smallest crayfish, the swamp crayfish, which does not exceed 30 mm in length, and the world’s largest crayfish, the Tasmanian giant freshwater crayfish, measuring up to 76 cm long and weighing 4.5 kg. The crayfish genus Cherax includes the common yabby, in addition to the farmed species marron and Queensland Red Claw.

Species from the genus Engaeus, commonly known as the land crayfish, are also found in Australia. Engaeus species are not entirely aquatic, because they spend most of their lives living in burrows. Australia has seven species of freshwater crab from the genus Austrothelphusa. These crabs live burrowed into the banks of waterways and can plug their burrows, surviving through several years of drought. The extremely primitive freshwater mountain shrimp, found only in Tasmania, are a unique group, resembling species found in the fossil record from 200 MYA.

A huge variety of marine invertebrates are found in Australian waters, with the Great Barrier Reef an important source of this diversity. Families include the Porifera or sea sponges, the Cnidaria (includes the jellyfish, corals and sea anemones, comb jellies), the Echinodermata (includes the sea urchins, starfish, brittle stars, sea cucumbers, the lamp shells) and the Mollusca (includes snails, slugs, limpets, squid, octopus, cockles, oysters, clams, and chitons). Venomous invertebrates include the Box Jellyfish, the blue-ringed octopus, and ten species of cone snail, which can cause respiratory failure and death in humans.

The Crown-of-Thorns Starfish usually inhabits the Reef at low densities. However, under conditions that are not yet well understood, they can reproduce to reach an unsustainable population density when coral is devoured at a rate faster than it can regenerate. This presents a serious reef management issue. Other problematic marine invertebrates include the native species Purple Sea-urchin and the White Urchin, which have been able to take over marine habitats and form urchin barrens due to the over harvesting of their natural predators which include abalone and Rock Lobster. Introduced invertebrate pests include the Asian Mussel, New Zealand Green-lipped Mussel, Black-striped Mussel and the Northern Pacific Seastar, all of which displace native shellfish.

There are many unique marine crustaceans in Australian waters. The best-known class, to which all the edible species of crustacean belong, is Malacostraca. The warm waters of northern Australia are home to many species of decapod crustaceans, including crabs, false crabs, hermit crabs, lobsters, shrimps, and prawns.

The Peracarids, including the amphipods and isopods, are more diverse in the colder waters of southern Australia. Less-well-known marine groups include the classes Remipedia, Cephalocarida, Branchiopoda, Maxillopoda (which includes the barnacles, copepods and fish lice), and the Ostracoda. Notable species include the Tasmanian giant crab, the second largest crab species in the world, found in deep water, and weighing up to 13 kg, and the Australian spiny lobsters, such as the Western rock lobster, which are distinct from other lobster species as they do not have claws.

Human impact and conservation

For at least 40,000 years, Australia’s fauna played an integral role in the traditional lifestyles of Indigenous Australians, who exploited many species as a source of food and skins, and for sport and pest control. Vertebrates commonly harvested included macropods, possums, seals, fish and the Short-tailed Shearwater, most commonly know as the Muttonbird. Invertebrates used as food included insects like the Bogong moth and larvae collectively called witchetty grubs and molluscs.

The use of fire-stick farming, in which large swathes of bushland were burnt to facilitate hunting, modified both flora and fauna - including large herbivores with a specialised diet, such as the flightless birds from the genus Genyornis. The role of Indigenous people in the extinction of the Australian megafauna is uncertain. No archæological evidence has been found to support the hypothesis that intensive hunting caused the extinction of megafauna, so climate change in Pleistocene is considered a more likely explanation for the megafauna extinction.

The impact of Aborigines on native species populations is widely considered to be less significant than that of the European settlers, whose impact on the landscape has been on a relatively large scale. Since European settlement, direct exploitation of native fauna, habitat destruction and the introduction of exotic predators and competitive herbivores has led to the extinction of some 27 mammal, 23 bird and 4 frog species.

Much of Australia’s fauna is protected by legislation; a notable exception is kangaroos, which are prolific and are regularly culled. The federal Environment Protection and Biodiversity Conservation Act 1999 was created to meet Australia’s obligations as a signatory to the 1992 Convention on Biological Diversity. This act protects all native fauna and provides for the identification and protection of threatened species.

In each state and territory, there is statutory listing of threatened species. At present, 380 animal species are classified as either endangered or threatened under the EPBC Act, and other species are protected under state and territory legislation. More broadly, a complete cataloguing of all the species within Australia has been undertaken, a key step in the conservation of Australian fauna and biodiversity.

In 1973, the federal government established the Australian Biological Resources Study (ARBS), which coordinates research in the taxonomy, identification, classification and distribution of flora and fauna. The ARBS maintains free online databases cataloguing much of the described Australian flora and fauna.

Australia is a member of the International Whaling Commission and is strongly opposed to commercial whaling-all Cetacean species are protected in Australian waters. Australia is also a signatory to the CITES agreement and prohibits the export of endangered species. Protected areas have been created in every state and territory to protect and preserve the country’s unique ecosystems.

These protected areas include national parks and other reserves, as well as 64 wetlands registered under the Ramsar Convention and 16 World Heritage Sites. As of 2002, 10.8% (774,619.51 km²) of the total land area of Australia is within protected areas. Protected marine zones have been created in many areas to preserve marine biodiversity; as of 2002, these areas cover about 7% (646,000 km²) of Australia’s marine jurisdiction. The Great Barrier Reef is managed by the Great Barrier Reef Marine Park Authority under specific federal and state legislation. Some of Australia’s fisheries are already overexploited,[18] and quotas have been set for the sustainable harvest of many marine species.

The State of the Environment Report, 2001, prepared by independent researchers for the federal government, concluded that the condition of the environment and environmental management in Australia had worsened since the previous report in 1996. Of particular relevance to wildlife conservation, the report indicated that many processes-such as salinity, changing hydrological conditions, land clearing, fragmentation of ecosystems, poor management of the coastal environment, and invasive species-pose major problems for protecting Australia’s biodiversity.