Animal Groups

Fur, feathers, skin or scales

The animal kingdom is divided into two groups—vertebrates and invertebrates. Invertebrates account for over 95% of all animal life on the planet and include insects, arachnids (spiders and scorpions), shellfish and a large variety of sea life such as sponges and coral.

Of the vertebrates, there are five main groups—amphibians, birds, fish, reptiles and mammals.


DragonflyInvertebrates are animals that do not have a backbone, or any bones at all, and are more varied than animals with backbones (vertebrates). They live in every type of habitat, though they are most commonly found in the sea.

One main feature of many invertebrates is the way they change as they grow. For example, a butterfly will start life as a caterpillar. After growing and eating over a number of weeks, a caterpillar will build a cocoon. Inside the cocoon, it will change until it is ready to emerge from the cocoon as a butterfly. This process is called ‘metamorphosis’.

Some of the invertebrates we have at Perth Zoo can be found in a special exhibit in the Nocturnal House. It includes Millipedes, Australian Tarantulas, Red-back Spiders, a Sydney Funnel Web Spider and a Scorpion. Watch as the scorpion glows under UV light!


Frogs and toads; newts and salamanders; and caecilians make up the group known as amphibians. Amphibians are ectothermic, which means their body temperature changes with their environment. Animals that are ectothermic are often referred to as being ‘cold-blooded’, although this is not a very accurate or helpful expression.

Splendid Tree FrogWater plays an important part in the lives of amphibians. Amphibians breathe and take in water through their skin. Keeping moist allows the exchange of oxygen and carbon dioxide between the amphibian and its environment to continue. Most amphibians also require water to mate and to lay and fertilise their eggs.

Other amphibians, called ‘direct developers’, lay their eggs in a jelly-like mass that does not need to be in water. They emerge from the mass as fully-formed amphibians. Even more amazing, is the Gastric Brooding Frog that carried around its eggs in its stomach. Eventually the frogs emerged from the mother’s stomach fully formed. Sadly, Gastric Brooding Frogs, which were found in Australia, are now believed to be extinct.

Amphibians around the world are threatened by climate change, habitat destruction and a disease called Chytrid fungus which have led to worldwide extinctions. Zoos and other conservation organisations are looking for a way to save amphibians.

To find out what Perth Zoo is doing to help, click here or look under the Conservation and Research section of this website.

What is the difference between a frog and a toad?
There are more than 4,500 known species of frogs and toads in the world. There is very little difference between frogs and toads. Frogs tend to have smoother skin than toads and their lives are more closely tied to water. Toads, however, live mostly on land and have warty skin.

What are caecilians?
Very little is known about these worm-like amphibians. So far 124 species have been discovered. They are limbless and have very sharp teeth. They have shiny skin which is ringed and has skin folds called annuli. Some caecilians live underground, while others live underwater. Those that live underwater have a fin and a tail they use for swimming.


Tuataras, lizards, snakes, turtles and crocodilians comprise the group reptiles. There are approximately 8,000 known species of reptiles. From the giant crocodile to tiny skinks and lizards, reptiles are found on all continents except Antarctica. Reptiles have scales instead of skin, which come in a wide range of colours. Some animals, like the chameleon or the Fijian Crested Iguana, can even change the colour of their scales in response to a threat.

Most reptiles lay eggs, although there are some that give birth to live young. These are called viviparous. There are even those that produce eggs inside the body, gestating the egg until it hatches and the young emerges fully developed. These are called ovo-viviparous.

Australia has more species of reptiles than any other continent. Its most famous residents are venomous snakes such as the Tiger Snake and Dugite. However, Australia has many other reptiles that are not venomous and pose little risk to humans. In fact, even venomous snakes prefer to steer clear of humans. There is a large number of lizards(such as the Perentie, Australia’s largest lizard at 2.5 m long), turtles and tortoises, and of course crocodiles.

Visit Australia’s rarest reptile, the Western Swamp Tortoise, in the Australian Wetlands at Perth Zoo. This reptile is found only in Western Australia. Thanks to a special breeding program at Perth Zoo, the future for these tortoises is looking brighter. Read more about this breeding program.

Many of the reptiles at Perth Zoo can be seen in the Reptile Encounter. Drop in for the special presentation every day at 11.15am for a ‘close encounter’.

And don’t forget the world’s largest tortoise, the Galapagos Tortoise. Two of these amazing giants can be found at Perth Zoo, opposite the Lesser Primates area.


It is very difficult not to be in awe of birds. Not only are they extremely varied in colour and size, they are masters of flight. There are nearly 10,000 species across the globe, found in all habitats—even Antarctica. They are specially adapted for flight with wings, powerful breast muscles, feathers, and light skeletons. While most can fly, there are exceptions such as penguins, emus, ostriches and cassowaries.

Splendid Fairy WrenBirds lay eggs which often require adults to build a nest and incubate the eggs until they hatch. Nests are then used to house the young until they develop enough to leave the nest and find their own food. The Malleefowl, however, is an exception.

Adult Malleefowl will build a mound of sand and leaf matter, opening and closing the mound to regulate the temperature. When the chicks hatch they are very advanced and already have a full covering of feathers. They struggle up through the sand and fend for themselves. Within 24 hours they are strong enough to fly.

Many birds have excellent eyesight (especially raptors like hawks and eagles) and they have amazing homing skills. In the cooler months, some birds will migrate to warmer climates, covering thousands of kilometres in one long, exhausting journey. They may also migrate for the breeding season.

There are about 800 species of birds found in or around Australia. These range from flightless birds like the Emu, Cassowary and Little Penguins, to hawks and eagles, ducks and seabirds. One of the most recognised bird species in Australia is the cockatoo. In Western Australia, Baudin’s and Carnaby’s Cockatoos are threatened by habitat destruction and poaching. A tree needs to be at least 100-years-old to develop a hollow large enough to house their eggs and young. The logging of forests is having a serious impact on their numbers. They also have to compete with introduced pests such as Rainbow Lorikeets and European Bees who take over their tree hollows.


Mammals are defined as animals that have hair and produce milk to feed their young. They are endothermic, which means they regulate their own body temperature. Mammals are divided into three types—marsupials, placental mammals and monotremes (egg-laying mammals).

There are only three species of egg-laying mammals or monotremes. These are the two species of echidna—long-beaked and short-beaked—and the platypus. Echidnas lay eggs in their pouch while the platypus lays its eggs in a burrow.

NumbatMarsupials, of which Australia has more than any other country, have a pouch where the young develops. The infant is born at an early stage of development and grows while nestled in the pouch.

Placental mammals form the largest mammal group. The young develop inside the mother’s uterus and are nourished through the placenta.

Mammals are found in almost all types of habitats. Some are found in the ocean (dolphins and whales), others are aerial animals like bats, and then there are those that live in trees, which are known as arboreal mammals. Many primates fall into this group, such as the orangutan. Then there are ground-living or ‘terrestrial’ mammals like elephants.


Fish form the largest group of vertebrates. Unlike the other vertebrate groups, the fish group is an informal collection of three classes: Osteichthyes (Bony Fish), Chondrichythyes (Cartilaginous fish) and Agnatha (Jawless fish). Most fish breathe using gills, have a body covered with scales, move by using their fins, and are ectothermic. Fish live in either fresh water or in the sea, however, some species live in both environments.

Jawless fish have an elongated body, smooth, scaleless skin and a jawless mouth.

Cartilaginous fish include some of the largest and most successful marine predators, namely sharks and rays. All cartilaginous fish have a skeleton made of cartilage. They have specialised teeth that are replaced throughout their lifetime. Their skin is covered with small, dense scales. Most species live in the ocean, however, some sharks and rays enter fresh water areas, while there are even those that live exclusively in fresh water.

More than 9 out of 10 species of fish are bony fish. They vary greatly in size and shape. They all have an internal skeleton, made wholly or partly of bone. The skeleton supports flexible fins that enable the fish to swim expertly and with precision. Most have a gas-filled swim bladder. The swim bladder controls the fish’s buoyancy which can be quickly altered.

Barramundi, Saratogas, Scats and Rainbow Fish share their home with Simmo, our Estuarine Crocodile, in the Australian Wetlands.

A freshwater fish can be found in the Australian Wetlands next to the Estuarine Crocodile. This exhibit was developed in partnership with the Western Australian Department of Fisheries. It seeks to increase awareness of the plight of Western Australian aquatic species by displaying native and introduced fish species found in south-west Western Australia.

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