The credit of being the world's largest known spider goes to male goliath bird-eating spider. According to Guinness book of world records, the total body length of this spider was 280 mm (leg-span: 28cm) with 50 gram of weight. But in General terms, goliath bird-eating spider falls to second position after giant huntsman spider by leg-span, but this species is largest if we count the ranking by mass. The Goliath bird-eating spider is large enough to eat a bird. Their diet consists primarily of insects and other invertebrates.

Mainly found in the northern South America, its habitat is the wet swamps and marshy areas deep within the primary rainforest. They live in burrows in the ground dug by the spiders themselves. Despite its name, the Goliath birdeater does not normally eat birds, although they may eat hatchlings. They don't make webs for hunting like other spiders but they sneaks up on their prey and injecting them with venom (stored inside their fangs) which paralyzes them. They have fangs large enough to break the skin of a human.

These spiders belongs to the family tarantula where tarantula is a generic name for hairy spiders. Unlike other spiders, they lack antennae and have four pairs of legs. Although they have 8 eyes but their visibility is quite low and can only see differences in the level of light. For signals they rely on sensory hairs that provide the feeling on the ground and in the air. Female have the largest lifespan comparing to males as females kills the males after mating. They usually eat them. Females have an average lifespan of 15 to 25 years while males have a lifespan of three to six years only.

Only a few species of spiders are dangerous to people but due to human nature, spiders are widely feared. Most of the spider produce worse effect than a mosquito bite and will only bite in self defence. Recluse spiders and widow spiders, considered spiders with medically serious bites, would flee and bite only when trapped. Funnel web spiders' bite has resulted in only 13 known human deaths in 50 years. Spider venoms, because they are harmful for insects but majorly harmless to humans, may be a less polluting alternative to pesticides. Most of the world's pests have had not developed any immunity to Australian funnel web spiders and they are easier to milk therefore they are a promising source of alternate pesticide. Scientists are engineering genes for the production of toxins into viruses.