Insects & Invertebrates comparison

Spider vs Tarantula: Key Differences Explained

The short answer

Tarantulas are spiders — one family within the order — so the names are nested. What sets them apart is fang orientation: tarantulas strike downward with parallel fangs, while most familiar spiders have fangs that pinch together sideways. Tarantulas are also large, long-lived and hairy, with females of some species living for decades, and New World species defend themselves with irritating hairs rather than by biting.

The main difference

A tarantula is a spider in the family Theraphosidae, distinguished by downward-striking parallel fangs, large size and exceptional longevity.

Tarantula is treated as though it were an alternative to spider rather than a kind of one, and the fang difference behind the split is genuinely interesting.

At a glance

Comparison of Spider and Tarantula across 6 dimensions, with an interpretation of each difference.
What differs	Spider	Tarantula	What it means
What the name covers	The whole order Araneae, with tens of thousands of described species	One family within it, Theraphosidae	Nested names again — every tarantula is a spider, and almost no spider is a tarantula.
Fang orientation	In most familiar spiders, fangs oppose each other and pinch sideways	Fangs are parallel and strike downward, requiring the spider to rear up	This is the anatomical basis of the split between the two main spider groups.
Size	Overwhelmingly small, most species only a few millimetres across	Large and heavy-bodied, with the biggest species spanning a hand	Size is what makes tarantulas conspicuous, but it is not what defines them.
Lifespan	Typically one to a few years in most species	Females of some species live for two decades or more	Longevity of this order is exceptional among terrestrial arthropods.
Respiratory structures	Many species have one pair of book lungs plus tracheae	Two pairs of book lungs, a more primitive arrangement	Respiratory anatomy is one of the formal characters separating the spider groups.
Primary defence	Varies enormously — webs, camouflage, fleeing, biting	New World species flick irritating urticating hairs from the abdomen	Urticating hairs are a distinctive defence not found across spiders generally.

What the name covers: SpiderThe whole order Araneae, with tens of thousands of described species
TarantulaOne family within it, Theraphosidae
Nested names again — every tarantula is a spider, and almost no spider is a tarantula.
Fang orientation: SpiderIn most familiar spiders, fangs oppose each other and pinch sideways
TarantulaFangs are parallel and strike downward, requiring the spider to rear up
This is the anatomical basis of the split between the two main spider groups.
Size: SpiderOverwhelmingly small, most species only a few millimetres across
TarantulaLarge and heavy-bodied, with the biggest species spanning a hand
Size is what makes tarantulas conspicuous, but it is not what defines them.
Lifespan: SpiderTypically one to a few years in most species
TarantulaFemales of some species live for two decades or more
Longevity of this order is exceptional among terrestrial arthropods.
Respiratory structures: SpiderMany species have one pair of book lungs plus tracheae
TarantulaTwo pairs of book lungs, a more primitive arrangement
Respiratory anatomy is one of the formal characters separating the spider groups.
Primary defence: SpiderVaries enormously — webs, camouflage, fleeing, biting
TarantulaNew World species flick irritating urticating hairs from the abdomen
Urticating hairs are a distinctive defence not found across spiders generally.

How they are related

Spiders form the order Araneae, and tarantulas are the family Theraphosidae within it. Tarantulas belong to the Mygalomorphae, a group retaining several ancestral features including downward-striking fangs and two pairs of book lungs, while most familiar spiders are Araneomorphae with sideways-pinching fangs. The name tarantula originally referred to an unrelated European wolf spider, which is a source of lingering confusion.

Telling them apart

Tarantulas are large, heavy-bodied and conspicuously hairy, with thick legs and a slow deliberate gait. They do not build the orb webs most people associate with spiders, instead lining burrows or retreats with silk. Fang orientation is definitive but requires a close view, so size, hairiness and build are the practical cues.

Large, hairy, thick-legged, slow-moving, living in a burrow or retreat rather than an orb web: tarantula, which is a spider. Almost anything else in the order — orb weavers, jumping spiders, wolf spiders, house spiders — is a spider but not a tarantula. The name is a subset, not an alternative.

Habitat and distribution

Tarantulas occupy tropical, subtropical and desert regions, with most species living in burrows or ground retreats and some arboreal species in tree hollows and among foliage. Spiders as a whole are found in nearly every terrestrial habitat on Earth, including intertidal zones and high mountains, with an enormous range of web-building and hunting strategies.

Diet and ecological role

All spiders are predators. Most take insects and other arthropods, and larger tarantulas will also take small vertebrates such as lizards and, occasionally, small mammals or birds — though that last case is far rarer than the name bird-eating spider suggests. Spiders digest prey externally, injecting enzymes and drawing up the liquefied contents.

Behaviour

Most tarantulas are sit-and-wait ambush predators, remaining near a burrow and seizing prey that passes. They do not build capture webs, instead using silk to line retreats and detect vibration. Spiders as a whole show an enormous range of strategies including orb webs, sheet webs, active pursuit, jumping and even mimicry of prey species.

Lifespan and life stages

Female tarantulas are among the longest-lived terrestrial arthropods, with some species documented beyond two decades in captivity, while males typically live only a few years and die not long after maturing. Most other spiders live a year or two. Captive figures generally exceed wild ones, and the two should not be quoted interchangeably.

People and these animals

Tarantulas are widely kept in captivity and several species have declined through collection and habitat loss, with international trade regulated for some. Spiders in general are major predators of insects and are ecologically valuable. Bites from tarantulas are painful but medically minor for most species, and the fear they provoke is disproportionate to the risk they present.

What they have in common

Both are arachnids with eight legs, two body sections, no antennae and no wings.
Both are predators that digest prey externally using injected enzymes.
Both produce silk, though they use it for very different purposes.
Both are ecologically valuable predators of insects and other arthropods.

Key differences

Tarantula names one family; spider names the entire order.
Tarantula fangs strike downward in parallel, unlike the sideways pinch of most spiders.
Tarantulas have two pairs of book lungs, a more ancestral arrangement.
Female tarantulas can live for decades, far longer than most spiders.
New World tarantulas defend themselves with urticating hairs, which other spiders lack.

Where people go wrong

Treating tarantula as an alternative to spider rather than a kind of spider.
Applying the name to European wolf spiders, which is where the word originally came from.
Assuming all tarantulas have urticating hairs, when Old World species do not.

Frequently asked questions

Is a tarantula a spider?

Yes. Tarantulas are the family Theraphosidae within Araneae, the spider order, so every tarantula is a spider. They belong to the Mygalomorphae, which retain ancestral features including downward-striking parallel fangs and two pairs of book lungs, while most familiar spiders belong to the Araneomorphae with fangs that pinch sideways. The distinction is a real anatomical one.

What are urticating hairs?

They are specialised barbed hairs on the abdomen of New World tarantulas, which the spider flicks off with its hind legs toward a threat. They cause intense irritation to skin, and are genuinely dangerous if they reach the eyes or are inhaled, which is why keepers are cautioned about them. Old World tarantulas lack them and tend to rely on defensive posture and biting instead.

Do tarantulas really eat birds?

Very rarely. The name goliath birdeater came from an eighteenth-century illustration of a tarantula with a hummingbird, and it stuck. Large tarantulas do take small vertebrates such as lizards, frogs and occasionally nestlings, but insects and other arthropods form the overwhelming majority of the diet. The bird-eating reputation substantially overstates how often it happens.

Are tarantula bites dangerous?

For most species the bite is painful — the fangs are large — but not medically serious for a healthy adult, and no tarantula is considered lethal to people. Some Old World species have more potent venom producing severe cramping. For New World species the urticating hairs are often the greater practical hazard. Any bite causing a severe or spreading reaction needs medical attention.

Read the full profiles

Sources and methodology

How this comparison is built: FaunaHub comparisons are assembled from the sourced animal profiles behind them rather than written as standalone claims. Figures such as size, mass, and lifespan are typical ranges that vary by subspecies, population, region, sex, age, and — where relevant — whether an animal lives in the wild or under human care, so they are presented as ranges rather than fixed values. Where a common name covers a group rather than a single species, the page says so instead of implying a species-to-species match. Conservation status changes over time and should be confirmed against the current IUCN Red List. Dimensions that could not be supported from the underlying profiles are omitted rather than filled in.

What this page does not do: it does not rank the two animals, predict the outcome of a confrontation, or present either one as stronger, smarter, or better. It is not veterinary, medical, first-aid, handling, capture, hunting, or pest-control guidance. For an animal in your care, or any situation involving injury, contact a qualified veterinarian, your local wildlife authority, or emergency services.

Sources and further reading

Authoritative references used for general educational context. External links open in a new tab. These sources do not endorse FaunaHub.

UniversityAnimal Diversity Web — Araneae (spiders) — University of Michigan order-level account
Wildlife referenceXerces Society for Invertebrate Conservation — Science-based invertebrate conservation resources
ReferenceEncyclopaedia Britannica — Animals reference — Editor-reviewed encyclopedia overview entries
UniversityAnimal Diversity Web — University of Michigan Museum of Zoology — Peer-edited reference accounts for animal species
ReferenceBritannica — Tarantula — Editor-reviewed encyclopedia entry
Wildlife referenceIUCN Red List of Threatened Species — Authoritative source for current conservation status

Last updated: 2026-08-04