What is the Most Venomous Spider in the World?

It 's an age old question and I'm sure you'd like an answer, well here goes:

This is a rather difficult question to answer as there are actually a number of very venomous spiders in the world, all of which have caused human deaths (in some cases the reported cases are anecdotal rather than scientifically recorded).

Of those, the Black Widow Spider (Lactrodectus mactans) of North America is the most well known of the so-called deadly spiders. Other members of the Lactrodectus family are found throughout many temperate parts of the world, such as Australia where it is known as the Red Back spider and New Zealand where it is known as the Katipo spider.

The Sydney funnel spider (Atrax robustus) of Australia is often quoted as being the spider with the most dangerous venom.

On the other hand; according to the Guinness Book of Records the world’s most venomous spiders is the Brazilian wandering spider (Phoneutria nigriventer).

This spider is believed to have the most active neurotoxic venom of any living spider. Its venom is so potent that only 0.006mg (0.00000021oz) is sufficient to kill a mouse.