The Deadly Sydney Funnel-Web Spider: Nature’s Most Venomous Predator

Just about all spiders are venomous. Venom is how they subdue and partially digest their prey. Most spider venom isn’t harmful to humans. However, there are a few spiders out there whose venom can make a human very sick or even kill them.

So, what is the most venomous spider in the world? Many scientists believe the Sydney funnel-web spider is the most venomous. Fortunately, this beast is only found around Sydney, Australia, which is how it got its name.

The Sydney Funnel-Web Spider

The Sydney funnel-web spider’s scientific name is Atrax robustus. Atrax is from Latin and means “dull black” or “dark.” Robustus means “strong” or “sturdy.” It is one of over 35 species of funnel-web spiders found in Australia.

The spider’s body is 0.4-2 inches long, with legs around 2.36-2.75 inches long. Males are smaller than females, but the male’s legs are longer. The carapace is glossy brown to black and hairless. The abdomen is dull black or plum-colored and covered with fine hairs, as are the legs. The spinnerets that produce silk are at the end of the abdomen and are plainly visible. The spider’s fangs are 1/4 inch long and can easily pierce shoe leather.

Where to Find the Sydney Funnel-Web Spider

Generally, Atrax robustus prefers places that are cool, moist, and dark. They can be found beneath rocks, foliage, fallen trees, rotting logs, the soil of crawl spaces, and even in compost piles. Their burrows may be tunnels or funnels, with trap doors or openings shaped like a T or a Y. These structures are between 7.9 and 23.6 inches long. The spider also lays trip lines at the entrance of its burrow.

The Sydney funnel-web spider eats insects, snails, millipedes, small vertebrates such as tiny lizards, and occasionally frogs. When prey wanders over the spider’s trip line, the spider rushes out, grabs it, bites it repeatedly then takes it inside its burrow to eat.

Sydney Funnel-Web Spider Behavior

The Sydney funnel-web spider is usually solitary, though females have sometimes been found in colonies. Females don’t wander from their burrows unless they’re forced to do so. Males, on the other hand, wander about looking for females. They are not only nocturnal, but they are also sensitive to sunlight, so the males are more active at night. They find the females by detecting the pheromones on the trip lines of their webs.

When threatened, the spider will throw up its front legs and display its fangs in a threatening posture. If the threat doesn’t go away, it will grab onto it and bite over and over. Another characteristic that makes this spider so dangerous is that it is aggressive. It doesn’t just run away and hide like other spiders. It also gives fewer “dry bites” than other spiders, which are bites that contain no venom.

How Dangerous Is This Spider?

One would think that the most venomous spider in the world must be an apex predator with nothing willing to take it on. However, that isn’t true. Its venom has different effects on different species, and some animals have no problem hunting and eating it. Centipedes will actually go into the burrows to get the spiders. Other predators include domestic cats and dogs, dingos, birds, rats, some marsupials, and large reptiles.

Unfortunately, funnel web venom has devastating effects on the human nervous system. Male venom is more toxic than female venom because it has a component called Robustoxin. This toxin is particularly lethal for primates, including humans. Symptoms include rapid heart rate, difficulty breathing, high blood pressure, and numbness around the mouth. Without treatment, fatalities have occurred in as little as 15 minutes. Fortunately, an antivenom was developed in 1981, and no deaths have occurred since it was introduced.