There are about 34,000 different known species of spiders in the world, but only a dozen of them are harmful to humans. Four of the deadliest spiders in the world are the following. These spiders should undoubtedly be avoided. Brown Recluse Spider The brown recluse spider is native to the United States. It prefers areas that are dark and quiet. They can be found both indoors and outside. Their characteristic marking is a dark violin shape on top. The brown recluse spider is not an aggressive spider, but will inject venom into its victims if it is pressed against the skin. In children, the elderly, and those with lowered immune systems, the venom will cause serious illness or death. Black Widow Spider   The black widow can be found in the southeastern United States. Their characteristic marking is a red hourglass   shape on their black stomach. It is not an aggressive spider. The black widow injects a neurotoxin   into its victims. The neurotoxin can interfere with nerves to muscle tissue. In children and the elderly, the neurotoxin can be fatal. Brazilian Wandering Spider   The Brazilian wandering spider has a few names such as the banana spider and the armed spider. They can be found in the regions of Central and South America where the climate is warm. These are highly aggressive spiders and are extremely dangerous. They wander around the forest floor and are commonly found in people's homes. It injects a neurotoxin which can cause death. Sydney Funnel-Web Spider   The Sydney funnel-web spider resides near Sydney, Australia. They can grow to 3 inches in length and have a dark and smooth body. They are extremely aggressive and are the most poisonous spiders. They will strike repeatedly, possibly causing death by injecting a neurotoxin into their victims. These four species of spiders are not all aggressive, but all can cause painful bites and serious bad reactions. Keep your eyes open because the best way to deal with these dangerous creatures is to avoid them. The brown recluse spider and the black widow are mainly different in   _  .
their living environment their aggressive character their way of attacking others their shape and color1