Travelers in countries such as Africa and Australia are often concerned about attacks by dangerous animals such as venomous snakes, crocodiles, big cats, and dangerous ocean-dwelling animals. A number of animals are in competition for the top spot on a list of the world's most dangerous animals, and some of the inhabitants of a list of dangerous animals might surprise you. Luckily, in general, unpleasant encounters with most of these animals can be avoided with the use of common sense and basic precautions.

Animals can be made dangerous by a variety of factors. Many dangerous animals are classified as a threat to humans because they carry venom which can injure or kill people. Others are physically dangerous: fast runners or swimmers with strong teeth and a fearless attitude. Still others are dangerous because of the diseases they carry. Some nations also have more dangerous animals than others: Australia, for example, has some of the most dangerous animals in the world including taipans and salt water crocodiles.

Most dangerous animals which carry venom are snakes or spiders. Some jellyfish also carry dangerous chemical compounds which can kill: the box jellyfish and Portuguese Man O'War are two examples. Most venomous snakes and spiders will not bother people unless they feel threatened. Examples of venomous snakes include African mambas, American rattlesnakes, Southeast Asian taipans, Indian cobras, and an assortment of vipers. In the arachnid world, black widow and brown recluse spiders cause hundreds of deaths worldwide each year. Another venomous and dangerous animal is the scorpion, which causes an untold number of deaths each year thanks to its distribution in remote areas without ready access to medical treatment.

Physically dangerous animals are those that most people are most familiar with. These animals include the big cats, sharks, and bears. In addition, elephants, hippopotami, and buffalo are extremely dangerous due to their protective nature and physical agility. The hippopotamus is actually Africa's most dangerous animal, because it is highly aggressive. Most early African explorers recorded unfortunate encounters with these animals, which have been known to overturn boats and savage their occupants for entertainment.

However, the world's most dangerous animals may come as a surprise: houseflies and mosquitoes. Both animals are classified as highly dangerous because of the diseases that they carry. Two to three million deaths each year are caused by mosquito borne illnesses such as malaria, yellow fever, and dengue fever. Houseflies carry over 200 pathogens including viruses and bacteria, and are ubiquitous enough to spread them all over the world along their daily rounds.