Weird Nature

Deadly Spiders, Ranked By How Deadly Their Venom Is (Or Could Be)

We share this planet with some pretty scary spiders - from massive, hairy tarantulas, to the infamous black widow. As terrifying as some of them are, the vast majority of spider species are actually not poisonous. And contrary to popular belief, many that are considered venomous won't cause significant harm to humans. 

There are many spiders that are simply misunderstood- species such as the Huntsman, which is large and hairy but very calm and non-venomous. However, there are a handful of spiders from around the world that you would most definitely want to avoid if you happen to come across them. 

Can spider venom kill you? The answer is yes, absolutely - there are antivenoms for most species, but the side effects and pain can still potentially land people in the hospital. These are the most venomous spiders ranked by how deadly their venom is, or could be - based upon an analysis of their venom - if they bit someone.  

  • Funnel Web Spiders
    Photo: David McClenaghan / Wikimedia Commons / CC BY 3.0

    Time To Kill: As fast as 15 minutes, but can take up to several days.

    Of the 35 species of funnel web spiders, the Sydney Funnel Web Spider has become widely known as the most deadly. Native to the Southeast Coast of Australia, it comes into frequent contact with humans by taking shelter in gardens or in shoes. 

    The spider's bite can be very painful because they have large fangs that are sharp enough to pierce fingernails. The venom includes a toxin that affects the nervous system, causing nerves to fire rapidly and the heart rate to rise.

    Oddly, the venom is only deadly for invertebrates and primates, so pets like dogs and cats can easily survive a bite. An antivenom was developed in 1981 and no one has died from this type of spider bite since.

  • Time To Kill: As little as half an hour, potentially longer.

    The Brazilian Wandering Spider is a large and aggressive arachnid from South and Central America. Although it does not eat bananas, it is commonly known as the Banana Spider because it can often be found hidden in banana shipments. 

    The Brazilian Wandering Spider's bite is initially very painful, with a burning sensation around the site. If left untreated within half an hour, symptoms can become systemic and very serious and include "high or low blood pressure, fast or a slow heartbeat, nausea, abdominal cramping, hypothermia, vertigo, blurred vision, convulsions and excessive sweating associated with shock." Although deaths are uncommon, there have been at least 10 official recorded fatalities.

    The spider bite can also cause a long-lasting and painful erection, so scientists have been studying the spiders for their potential in developing erectile dysfunction drugs. 

  • Brown Recluse
    Photo: Mike Keeling / Flickr / CC BY-ND 2.0

    Time To Kill: Around 14 hours, based on one documented case of a 7-year-old boy.

    The Brown Recluse is native to the United States, and although bites occur frequently, they are rarely deadly. They have a very distinctive pattern on their backs that resembles a violin, yet they are still often mistaken for other common house spiders. 

    Their bite can cause skin necrosis, but many bites simply heal on their own. In severe cases, death can occur if the venom becomes systemic. 

  • Black Widow
    Photo: Chuck Evans / Wikimedia Commons / CC BY 2.5

    Time To Kill: Unknown, but severe symptoms occur within a few hours of bite.

    Although their bites don't always cause death, Black Widows are infamous across North America for their painful and dangerous bites. Females have a distinctive red hourglass on the underside of their jet-black bodies, and get the "widow" in their name from the act of killing the males after mating. 

    Bites can become painful within 15 minutes, and the symptoms experienced can include paralysis of the diaphragm, fever, weakness, chills, nausea, headache, and sweating. Those most at risk from Black Widow bites are the young, elderly, or immunocompromised.