Do you think that Australia is ruled by humans? Maybe by kangaroo or bunnies, or even dingo? No! These are snakes and pythons. You can find then anywhere and snakes definitely are last in Australia food chain. They will eat everyone else. Also, they are most poisonous in the world. Don't forget about spiders, centipedes, sharks and jellyfish. Last one have poison 100 times stronger than cobra poison. If you will get bitten by octopus, no need to rush to hospital, there is no antidote for this. Australia also have special ticks. They'r neurotoxin can cause paralysis. Swimming in fresh water not recommended as you can catch amoebic meningitis with survival chance 3%. Do you still want to go to Australia?
What would be the first? List is long indeed. With Australia animal poison you could kill all humans on planet several times. On the top of the food chain here are pythons. They can eat an alligator, kangaroo or dead cow. Size is not an obstacle. Most important is python's length. Olive python can grow up to 4 m and it is not a problem to pull out a cow fallen into crevice.
If it is not enough then in Australia lives 6 from 12 most poisonous snakes in the world. Poison can kill in a blink of an eye. Eastern brown snake is small enough to fit in a golf pit but you can find snakes anywhere. Some snake can take a free ride on a plane's wings.
Saying snakes are everywhere I mean it. Your house is their house. They can wait for you in wardrobe or bed. When going to toilet, check toilet bowl. They can be hiding inside...
In order to protect yourself from snakes you can have some spiders. They are big and they can catch a snake. Golden orb weaver lives in suburbs and because of that they grow bigger and lay more eggs. It can be 15 cm long. Of course there are spiders who will live in your house to reproduce. If they will bite you will die in a long and horrible death.
Please don't think that you will be saved from poisonous animals if you will go swimming. There are lot of poisonous animals who can be very, again, deadly. These can be fishes, snails or octopus with poison than can make your surfing session the last one.
Get acquainted - this is a perfect killer. After billions years of evolution body consists almost entirely from water - 99%. You can't see any brains or nerve cells, you can't even notice it but they have stingers! Other animal poison can affect some organ system but jellyfish poison have complex effect. It starts with paralysis and finishes with external digestion. This is Irukandji jellyfish and it inhabits Northern Australia waters. After it bites you can have lethal brain hemorrhage but before that you will have burning sensation, seizures, migraine and vomiting. Also you will feel true horror.
It is said that Australia have wonderful beaches. I think sharks agrees with that but they are most innocent from this list. They can also kill you but they don't have paralytic poison which stops your breathing. You can loose leg or a hand but you will be alive. Sharks might be eaten by saltwater crocodile and you definitely don't want to meet them!
I forgot to mention Australian paralysis tick. Poison is stronger than snakes have. It can cause anaphylactic shock and paralysis. When walking in rain forest, remember - you are one step aside from hospital.
That is Australia! G'day - ...good die