Australia's isolation from the rest of the world over millions of years has led to the evolution of forms of life found nowhere else. Probably the strangest of all is the platypus. This monotreme, or egg-laying marsupial, has webbed feet, a ducklike bill, and a tail like a beaver's. It lays eggs, and the young suckle from their mother. When a specimen was first brought back to Europe, skeptical scientists insisted it was a fake -- a concoction of several different animals sewn together. You will probably never see this shy, nocturnal creature in the wild, although there are a few at Sydney's Taronga Zoo.

Another strange one is the koala. This fluffy marsupial, whose nearest relative is the wombat, eats virtually indigestible gum (eucalyptus) leaves and sleeps about 20 hours a day. There's just one koala species, although those found in Victoria are much larger than their brethren in more northern climes.

Australia is also famous for kangaroos. There are 45 kinds of kangaroos and wallabies, ranging in scale from small rat-size kangaroos to the man-size red kangaroos.

The animal you're most likely to come across in your trip is the possum, named by Captain James Cook after the North American opossum, which he thought they resembled. (In fact, they are from entirely different families of the animal kingdom.) The brush-tailed possum is commonly found in suburban gardens, including those in Sydney.

Then there's the wombat. There are four species of this bulky burrower in Australia, but the common wombat is, well, most common. You might come across the smaller hairy-nosed wombat in South Australia and Western Australia.

The dingo, thought by many to be a native of Australia, was in fact introduced -- probably by Aborigines or traders from the north. These wild dogs vary in color from yellow to a russet red and are heavily persecuted by farmers. Because dingoes can breed with escaped "pet" dogs, full-blooded dingoes are becoming increasingly rare.

The carnivorous marsupial Tasmanian devil can be found in (you guessed it) the island-state of Tasmania, though a virulent face cancer has swept through the animals and is quickly wiping out the wild population.

Commonly seen birds in Australia include the fairy penguin or Little Penguin along the coast, black swans, parrots and cockatoos, and honeyeaters.

Dangerous Natives

Snakes are common throughout Australia, but you will rarely see one. The most dangerous land snake is the taipan, which hides in the grasslands in northern Australia -- one bite contains enough venom to kill up to 200 sheep. If by the remotest chance you are bitten, immediately demobilize the limb, wrapping it tightly (but not tight enough to restrict the blood flow) with a cloth or bandage, and call tel. 000 for an ambulance. Antivenin should be available at the nearest hospital.

One creature that scares the living daylights out of anyone who visits coastal Australia is the shark, particularly the great white (though these marauders of the sea are uncommon, and mostly found in cooler waters, such as those off South Australia). Shark attacks are very rare, particularly when you consider how many people go swimming. A total of 194 people have been killed in shark attacks in Australia over the past 2 centuries. Some years there are none, other years there have been up to three in a year, but the average is around one per year.

There has not been a single fatality on a Sydney beach since 1963, though in February 2009 there were three shark attacks in Sydney. The first involved a navy diver who was attacked by a bull shark in Sydney Harbour, not far from the Opera House. Doctors later amputated his arm and a leg. The second attack involved a 2.5m (8 1/4-ft.) great white shark, which savaged a surfer's hand off Bondi Beach. In the third attack, a shark bit a teenage surfer's leg to the bone off Avalon, one of Sydney's northern beaches. In February 2010 a surfer was bitten on the leg by a usually non-aggressive wobbegong shark.

Apart from the great white, the most dangerous sharks are the tiger shark and the bull shark. Bull sharks are particularly annoying as they tend to swim up rivers.

There are two types of crocodile in Australia: the relatively harmless freshwater croc, which grows to 3m (10 ft.), and the dangerous estuarine (or saltwater) crocodile, which reaches 5 to 7m (16-23 ft.). Freshwater crocs eat fish; estuarine crocs aren't so picky. Never swim in or stand on the bank of any river, swamp, or pool in northern Australia unless you know for certain it's croc-free.

Spiders are common all over Australia, with the funnel web spider and the red-back spider being the most aggressive. Funnel webs live in holes in the ground (they spin their webs around a hole's entrance) and stand on their back legs when they're about to attack. Red-backs have a habit of resting under toilet seats and in car trunks, generally outside the main cities. Caution is a good policy.

If you go bushwalking, check your body carefully. Ticks are common, especially in eastern Australia, and can cause severe itching and fever. If you find one on you pull it out with tweezers, taking care not to leave the head behind.

Fish to avoid are stingrays (remember poor old Steve Irwin and his tragic death due to a stingray barb through the heart), as well as porcupine fish, stonefish, and lionfish. Never touch an octopus if it has blue rings on it, or a cone shell, and be wary of the painful and sometimes deadly tentacles of the box jellyfish along the northern Queensland coast in summer. This jellyfish is responsible for more deaths in Australia than snakes, sharks, and saltwater crocodiles.

Closely related to the box jellyfish is the Irukandji, which also inhabits northern Australian waters. This deadly jellyfish is only 2.5 centimeters (1 in.) in diameter, which makes it very hard to spot in the water.

If you brush past a jellyfish, or think you have, pour vinegar over the affected site immediately -- authorities leave bottles of vinegar on beaches for this purpose. Vinegar deactivates the stinging cells that haven't already affected you, but doesn't affect the ones that already have. If you are in the tropics and you believe you may have been stung by a box jellyfish or an Irukandji, seek medical attention immediately.

In Sydney, you might come across "stingers," also called "blue bottles." These long-tentacled blue jellyfish can inflict a nasty stinging burn that can last for hours. Sometimes you'll see warning signs on patrolled beaches. The best remedy if you are severely stung is to wash the affected area with fresh water and have a very hot bath or shower (preferably with someone else, just for the sympathy).

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.