Spider

Spiders (order Araneae) are air-breathing arthropods with eight legs, a pair of fang-tipped mouthparts called chelicerae, and silk-producing organs called spinnerets. Their bodies are divided into two sections - the cephalothorax at the front and the abdomen at the rear - joined by a small cylindrical waist called the pedicel.

Spiders range enormously in size. The smallest known species measure less than 0.37 mm in body length, while the largest tarantulas can have a body length of up to 90 mm and a leg span of up to 250 mm.

Spiders are found on every continent except Antarctica and have made themselves at home in nearly every land habitat on Earth. As of early 2026, more than 53,000 species have been recorded. They are the largest order of arachnids and rank seventh in total species diversity among all orders of organisms.

Spider-like arachnids with silk-producing structures appeared around 386 million years ago, during the Devonian period. True spiders, very similar to the most primitive surviving group alive today, have been found in rocks from the Carboniferous period, between 318 and 299 million years ago.

The two main groups of modern spiders - Mygalomorphae (which includes tarantulas) and Araneomorphae - first appeared during the Triassic period, more than 200 million years ago.

The word spider itself comes from the Proto-Germanic word meaning literally 'spinner', a reference to web-making, which in turn traces back to a Proto-Indo-European root meaning 'to draw, stretch, spin'.

Almost all spiders are predators, feeding mainly on insects and other spiders. They use a wide range of hunting strategies - building sticky webs, actively chasing prey, ambushing from burrows, or even swinging a sticky ball of silk like a lasso to catch moths. Spiders cannot eat solid food; instead they liquefy their prey using digestive enzymes and then suck up the resulting fluid.

Spiders detect the world largely through vibration and touch. Tiny bristles on their bodies respond to air currents and physical contact, and web-building spiders are exquisitely sensitive to vibrations in their silk. Active hunters tend to rely more on their eyes, and some jumping spiders have visual acuity ten times sharper than that of dragonflies.

Most spiders lead solitary lives, but a minority are social, building communal webs that can house anywhere from a few individuals to colonies of up to 50,000. Courtship in spiders tends to be elaborate - males use vibrations, dances, or careful patterns of touch to identify themselves to females and avoid being eaten. Females lay up to 3,000 eggs in silk egg sacs and many species actively care for their young, carrying spiderlings on their backs or sharing food with them.

Spiders are ectotherms, meaning environmental temperature directly affects how active they are. Because many species are nocturnal, the extent to which spiders feed on nectar may have been underestimated.

Most spiders live for one to two years. However, tarantulas and other mygalomorph spiders can live for over 20 years, and one Australian female trapdoor spider was documented to have lived for 43 years in the wild before dying from a parasitic wasp attack.

Males of most species survive a few matings, limited mainly by their short lifespans. Parasitic wasps are a significant natural threat to many spider species.

The venom of a few spider species is dangerous to humans. Scientists are actively researching spider venom for potential medical uses and as a basis for non-polluting pesticides.

This is general awareness only, not veterinary advice. If you find an injured or unwell wild animal, contact a vet or a wildlife rescue.

Are spiders really dangerous to humans?

The venom of a few species is dangerous to humans. Research into spider venom is actually ongoing, with scientists exploring its potential uses in medicine and as an environmentally friendly pesticide.

How long does a spider live?

Most spiders live for one to two years. Tarantulas and related mygalomorph spiders are a striking exception - they can live for over 20 years in captivity, and at least one wild individual is documented to have reached 43 years of age.

Do spiders only eat insects?

Most spiders are predators that feed mainly on insects and other spiders, but the picture is more varied than that. Some juveniles feed on plant nectar, some species scavenge dead arthropods, and a few large species are capable of taking birds and lizards. One jumping spider species gets over 90% of its food from plant material.

Is a fear of spiders normal?

An irrational fear of spiders is called arachnophobia. Spiders have become common symbols in art and mythology, symbolising various combinations of patience, cruelty and creative powers.

Do spiders have good eyesight?

It depends on the species. Web-building spiders tend to have poor vision and rely far more on sensing vibrations. Active hunters, particularly jumping spiders, can have remarkable eyesight - some jumping spiders have visual acuity ten times greater than that of dragonflies, which are considered the best-sighted insects.

Can spiders really spin different kinds of silk?

Yes - spiders have at least six types of silk gland, each producing a different type of silk. Silk is used for webs, egg sacs, safety lines, nest-building, and even as tiny 'parachutes' that allow young spiders to disperse on the wind. Spider silk is comparable in tensile strength to nylon but is far more elastic.

Spiders extend their legs not with muscles but with hydraulic pressure - pumping fluid into them like tiny biological pistons. Because of this, a spider with a punctured cephalothorax cannot extend its legs, and the legs of dead spiders curl up.

Jumping spiders can leap up to 50 times their own length by suddenly increasing the blood pressure in their third or fourth pair of legs.

An estimated 25 million tonnes of spiders kill between 400 and 800 million tonnes of prey every year.

Some spiders use their webs as ears. Giant webs can function as extended, reconfigurable auditory sensors, picking up sound vibrations from the surrounding environment.

Spider silk genes have been inserted into mammals and plants by scientists hoping to use them as living silk factories - a testament to just how remarkable the material is.