Spiders

Spiders are a group of land-dwelling, carnivorous invertebrates. They differ from insects by having only two main body segments (rather than three), four pairs of walking legs (rather than three) and no antennae. Spiders have jointed limbs and a hard exoskeleton that protects their body. This places spiders in them phylum of animals called Arthropoda; which includes scorpions, crustaceans and insects. Almost all spiders are venomous and often use their venom to paralyze their prey.

Where are spiders found?

Spiders are found almost exclusively on land across all continents apart from Antarctica. A number of species can swim and feed in water but only one species is known to live entirely in aquatic environments – the diving bell spider (Argyroneta aquatica) – and even this species must still breathe air. There are animals called sea spiders which live in the oceans and are most common in the Mediterranean. Although they are related to spiders, they are not ‘true spiders’ and are in fact more closely related to scorpions.

How many species of spiders are there?

More than 32,000 species have been described from around 3000 different genera.

Do all spiders make webs?

Short answer, no. Technically, webs are used to catch prey and only around half of all species hunt using webs. All spiders can however produce silk but many do so for other purposes such as protecting eggs, creating shelter and for reproduction.

What do spiders feed on?

The main source of food for most spiders is insects. Some species also feed on other invertebrates and a few species even manage to feed on small birds. Once prey is caught, spiders use their fangs to inject the prey with venom.

Spiders have developed a number of elaborate methods to catch prey using their silk in various ways. As commonly seen, many spiders built complex webs to unforgivingly trap flying insects as they fly by. Net casting spiders weave small nets that are thrown over passing prey and other species lay silk trap wires to trigger the presence of prey nearby.

Last edited: 1 June 2015

FREE 6-Week Course

Enter your details to get access to our FREE 6-week introduction to biology email course.

Learn about animals, plants, evolution, the tree of life, ecology, the microscopic world, fields of biology and more.

Powered by ConvertKit