The species considered most approachable are those that exhibit extreme docility, a non-aggressive temperament, and venom that is not medically significant to humans. Despite common fear, the vast majority of the over 50,000 spider species worldwide are harmless, and many encountered frequently are highly non-threatening. This focus on low-risk behavior and mild reactions is the true measure of a “friendly” spider.
Defining Docility and Risk
A spider’s temperament is measured by three criteria: its likelihood to perceive humans as a threat, the potency of its venom, and its tendency to bite. Docile species are characterized by a reluctance to engage, viewing humans as neither prey nor a challenge. They typically choose flight as their primary defense mechanism.
The medical significance of a spider’s venom determines its risk level. Docile spiders possess venom potent enough only to immobilize small insect prey. If a bite occurs, the effect on a human is usually localized, resulting in minor irritation comparable to a mosquito bite or a bee sting. This mild reaction, combined with a tendency to flee, makes these species low-risk.
The Most Popular Docile Pet Species
The most popular docile spiders kept as pets are New World tarantulas and certain jumping spiders, due to their calm dispositions and manageable venom. Tarantulas like the Chilean Rose Hair (Grammostola rosea) and the Mexican Red Knee (Brachypelma hamorii) are celebrated in the pet trade for their slow movements and general aversion to biting. Female Mexican Red Knees can live for decades and are often recommended for first-time keepers because they prefer to retreat into their burrows when disturbed rather than exhibit aggression.
The Chilean Rose Hair tarantula is similarly popular for its quiet, calm demeanor and hardiness. Both species possess venom comparable to a bee sting, which is not medically significant for most people. Their primary defense mechanism, however, is not biting, but rather flicking urticating hairs from their abdomen, which can cause localized irritation to the skin or eyes.
Jumping spiders (family Salticidae) are also popular due to their curious and interactive nature. These small, day-active hunters possess exceptional vision and often turn their bodies to observe people. Despite their ability to bite if mishandled, their venom is designed for small insects and poses virtually no threat to humans, making them highly docile observation pets.
Common Harmless Household Inhabitants
Many spiders encountered inside homes are harmless and beneficial, often preying on household pests. The Cellar Spider (Pholcus phalangioides), often mistaken for a harvestman, is a common resident known for its small, delicate body and long legs. They are frequently found in basements and crawl spaces, building messy, tangled webs.
Cellar spiders are not medically important, and their fangs are often too short or weak to penetrate human skin effectively, making a bite rare. Another widespread species is the American House Spider (Parasteatoda tepidariorum), which is found across the world and is the most commonly sighted spider in North America. These cobweb spiders are small, dull-colored, and pose no threat, often choosing to flee when disturbed. The American House Spider will only bite defensively, and any reaction is usually mild.
Why Spiders Bite Only in Defense
The fundamental reason most spiders are harmless is that they do not view humans as prey. Injecting venom into a large creature is a waste of energy and a substance needed to secure their next meal. Consequently, nearly all spider bites occur only as a defensive last resort.
A spider will typically only bite when it feels physically threatened, such as when it is accidentally trapped, crushed against skin, or protecting an egg sac. Even highly venomous species, like the black widow or brown recluse, are naturally shy and non-aggressive. Bites usually result from accidental contact when the spider is pressed against the skin. The primary behavior of a spider encountering a human is to retreat and hide.