The world’s most extreme spiders

Spiders are incredibly diverse but there’s a few species that stand out as being the most extreme of them all.

The world’s heaviest spider

A member of the tarantula family, the Goliath birdeater takes the prize for the heaviest spider in the world. As is the case with many spiders, the females are bigger than the males because they produce eggs. Female Goliath birdeaters can weigh in at around a staggering 100 grammes and have a huge leg span of just under 30 centimetres.

Its name, however, is actually quite deceiving, as this species, despite its huge size, rarely actually preys on birds. Native to the rainforests of South America, the burrowing Goliath birdeater primarily feeds on insects. It also occasionally eats small animals such as frogs as well as mice and other rodents.

Goliath birdeaters have poor eyesight, so they rely on sensitive hairs on their legs to detect the vibrations of prey. Like most arachnids they use venom delivered through their fangs to paralyse large prey. This venom isn’t dangerous to us. Since spiders can’t consume solid food, they liquefy their prey’s insides then suck them out.

To protect themselves from predators, Goliath birdeaters have urticating hairs on their abdomen that cause irritation when touched. They detach them by rubbing their legs together and then flick them towards the threat. Females, in fact, use these same hairs in their egg sac silk to defend their eggs.

The spider with the longest legs

There are more than 1,000 species of huntsman spider. They get their name from the way they catch their prey. Instead of using a web, they hunt their prey. Huntsman spiders are also sometimes called crab spiders due to their crab-like legs, which allow them to move sideways, run quickly and even jump.

The largest species of them all is the giant huntsman spider, which is found in Laos. Males can have a leg span of around 30 centimetres – the length of a standard ruler. Giant huntsman spiders live on the walls of caves, using their long legs to grip the surface. They tend to stay near the entrance where there’s more light.

As is common in the spider world, cannibalism sometimes occurs after mating, with the female eating the male. This behaviour provides her with essential nutrients needed to produce eggs.

The largest web and strongest silk

Spider silk is the strongest known natural or human-made fibre in the world. There are several types of spider web, including orb, funnel, sheet and triangle. The largest web and strongest silk are made by a species of orb-weaving spider called Darwin’s bark spider.

Discovered in 2009 and named in honour of Charles Darwin, this arachnid is native to Madagascar and typically lives near rivers and streams.

Darwin’s bark spiders produce silk that’s around 10 times tougher than Kevlar – the synthetic fibre used in bulletproof vests. In fact, it’s considered the toughest biological material ever discovered.

In addition to having incredibly strong silk, these spiders also build enormous webs with central orbs that can span more than two metres. They build these huge webs over rivers, which greatly increases their chances of catching flying insects such as dragonflies.

To build these giant webs, they release a large amount of silk into the air, which is then pulled along the river by the wind. At some point, it snags on foliage across the water, creating a bridging line from which the spider constructs the orb.

The most venomous spider

Although nearly all spiders are venomous, most of them aren’t venomous to us. The Brazilian wandering spider, however, is one of the few species that can cause harm if they bite us.

Native to South and Central America, the Brazilian wandering spider moves about the forest floor at night in search of prey. This nocturnal hunting behaviour is what gives the species its name.

Brazilian wandering spiders have leg spans that can reach up to 15 centimetres. They’re typically brown and hairy, and some species display bright red or orange markings on the underside of their legs or near their fangs. During the day, they hide in dark, sheltered areas such as log piles.

This spider’s venom is extremely powerful, capable of causing serious symptoms in people, including intense pain, muscle paralysis, difficulty breathing and, in rare cases, death. Despite its lethal reputation, fatal bites are in fact very rare, as the spider often dry bites without injecting venom as a defensive warning. Plus, the availability of antivenom means that venom-injecting bites often now don’t result in death.

Though it’s often listed as one of the world’s most venomous spiders, the Brazilian wandering spider is not naturally aggressive. It generally only bites when it feels threatened or disturbed.

They’re known to hide in banana palms for shade and when the bananas are harvested, it can lead to the spiders being distributed widely around the world. This has earned them the nickname banana spiders.

Jumping spiders

Jumping spiders are a widely distributed group of spiders known for their incredible vision and agile movements. They belong to the Salticidae family that has more than 6,000 species.

Unlike many other spiders, jumping spiders don’t spin webs to catch prey. Instead, they’re active hunters, using their powerful legs to leap several times their body length to pounce on insects. Before jumping, they anchor themselves with a strand of silk that acts like a safety rope so that if they miss, they can climb back up and try again.

Jumping spiders have remarkable vision. They have four pairs of eyes, with two large, forward-facing central eyes that give them excellent depth perception and almost 360-degree vision. Their eyesight is among the best in the spider world, allowing them to track, stalk and leap precisely onto prey.

They’re also known for their complex courtship dances. In many species, especially those with brightly coloured males, the spiders will perform elaborate displays of leg-waving, vibrations and even rhythmic movements to impress females.

Spiders that live underwater

Although most spiders are land-dwelling creatures, there’s one species that lives almost entirely underwater – the water spider. This is the only known spider in the world that spends the majority of its life submerged.

Water spiders are found in freshwater environments such as lakes, ponds, canals and slow-moving streams, mainly across Europe and parts of northern Asia. Despite living underwater, they still need to breathe air, so how do they manage it?

Well, it’s all because of a silk structure called a diving bell. This functions much like the diving bells once used by divers before the invention of scuba gear.

To make it, the spider begins by spinning a silken dome attached to underwater plants. Then it swims to the surface and traps air bubbles on the fine hairs of its legs and abdomen.

These bubbles are carried back down and released into the dome. Over time, the dome fills with air, creating a space where the spider can breathe, rest, store food and even raise its young.

This diving bell acts like an underwater home and the spider rarely leaves it for long. It hunts from this air-filled chamber, capturing aquatic insects, small crustaceans and other tiny prey. If oxygen levels drop, the spider will bring down more air from the surface.

One unusual trait of the water spider is its reversed sexual size dimorphism – with males being larger than females, which is the opposite of what’s seen in most spider species. Larger males are more mobile in the water, which is crucial for finding and courting females. Their larger size and longer front legs enhance their diving ability, allowing them to move more efficiently and reach potential mates more quickly.

Next time you see a spider in your home or garden, think about the incredibly diverse class that they’re part of.