When my pet tarantula outlived three family dogs, I realized these weren’t ordinary spiders. With fangs like vampire teeth and specialized defense hairs that make poison ivy seem pleasant, tarantulas are spider outliers.
Ever wondered how these gentle giants differ from the web-spinners in your garden?
Many people are surprised to learn that tarantula hunting techniques involve stalking and ambushing prey rather than trapping it in webs.
Key Points:
- Tarantulas belong to Mygalomorphae suborder, while true spiders belong to Araneomorphae
- Tarantulas have downward striking fangs, true spiders have sideways striking fangs
- Tarantulas can live up to 30 years, but most true spiders live only 1-3 years
- True spiders build complex webs, while tarantulas make limited silk use
- New World tarantulas have special urticating hairs for defense
Basic Differences
You know how some families have that one ancient great-aunt who hasn’t changed her hairstyle since the 1960s? That’s basically tarantulas! They’re part of the Theraphosidae family and are the old-timers of the spider world, barely changing in 300 million years. True spiders, on the other hand, are like their hip, constantly-evolving cousins.
Last weekend, I was watching a nature documentary that mentioned the World Spider Catalog – apparently there are only about 2,000 kinds of tarantulas but a whopping 48,000 kinds of true spiders! That’s like comparing the menu at your local diner to the entire cookbook section at Barnes & Noble. Families like Araneidae (orb-weavers) and Salticidae (jumping spiders) are all part of the true spider crew.
“The evolutionary divergence between these groups happened around 200 million years ago. Tarantulas kept many ancient traits, while true spiders developed new ways to survive,” explains Dr. Norman I. Platnick, former spider expert at the American Museum of Natural History.
How They Look
Telling these spiders apart is easier than spotting the difference between a Great Dane and a Chihuahua – both dogs, but clearly not the same beast!
| Feature | Tarantulas | True Spiders |
|---|---|---|
| Size | Often big (1-11 inches) | Usually smaller (most under 1 inch) |
| Fangs | Orthognathous (point down) | Labidognathous (cross like pincers) |
| Body | Chunky, furry | Often sleek |
| Eyes | Usually 8 eyes in simple pattern | 8 eyes in various patterns |
| Special hairs | Urticating hairs in New World species | None |
The fang difference is super important! I remember when my friend’s Chilean Rose Tarantula (Grammostola rosea) was eating, and I could clearly see those fangs pointing straight down (paraxial fangs) – like tiny vampire teeth! True spiders like widow spiders (Latrodectus) have fangs that move sideways (diaxial fangs), more like crab pincers. Talk about different table manners!
Breathing and Silk
Inside, they’re as different as scuba divers and snorkelers:
- Tarantulas have two pairs of book lungs for breathing
- True spiders have one pair of book lungs plus a tracheal system
- Tarantulas have 2-4 spinnerets (silk-making parts)
- True spiders typically have 6 spinnerets in a different arrangement
This affects how they use silk. After watching the recent Spider-Man movie, I couldn’t help but think how Nephila (golden silk orb-weavers) would make much better superheroes with their amazing webs! Meanwhile, the Brazilian Salmon Pink Tarantula (Lasiodora parahybana) uses about as much silk as I use wrapping paper – just enough to line its home and that’s it.
Hunting and Defense
Their hunting styles are as different as a sniper and a trap-setter:
- Most tarantulas are ambush predators that wait for prey
- Many true spiders use web capture methods
- Some true spiders are active hunters with good eyesight
- Tarantulas rely on feeling vibrations due to poor visual acuity
For defense, New World tarantulas like the Mexican Red Knee Tarantula (Brachypelma hamorii) use urticating hairs – it’s like having a pocketful of itching powder they can throw at enemies! I learned this the hard way at a pet expo in 2022 when I got just a bit too close to a display. My arm itched for days!
True spiders like those in the recluse spiders (Loxosceles) family rely on speed, hiding, or venom – more of a “live to fight another day” philosophy.
Lifespan and Babies
The lifespan difference blows my mind – it’s like comparing tortoises to mayflies:
- Female tarantulas can live 15-30+ years
- Female true spiders usually live 1-3 years
- Male tarantulas live 3-8 years
- Male true spiders often live less than 1 year
The American Arachnological Society has studies showing that tarantulas grow much slower, with females molting frequency dropping to once every 1-2 years as adults. That’s slower than my grandpa shopping for a new car!
When making babies, tarantulas produce egg sacs with 50-2,000 eggs. True spiders usually have smaller clutch sizes of 10-400 eggs. It’s like comparing a kindergarten class to the entire student body of a high school!
People and Spiders
Despite what many think, tarantulas aren’t more dangerous than true spiders. It’s like being afraid of a Great Dane when the snippy Chihuahua is actually more likely to bite you!
- Sydney funnel-web spider (Atrax robustus) and Brazilian wandering spiders (Phoneutria) are true spiders with dangerous venom
- Tarantula bites cause pain but rarely serious problems
- The British Tarantula Society reports about 100,000+ tarantulas are kept as pets each year
- Only 50 tarantula bites needing medical help are reported yearly in the US
“People often fear tarantulas more because of their size, but some of the most medically significant spider bites come from much smaller true spiders,” says Barbara York Main, expert on mygalomorph spiders.
Just last month, a viral TikTok showed a pet owner letting their tarantula crawl on their face – not something I’d recommend, but it did highlight how docile many tarantulas can be compared to their reputation!
Summary
Tarantulas and true spiders are like distant cousins who only see each other at family reunions – related, but living completely different lives. Their spider taxonomic differences show us how animals can take different evolutionary paths, kind of like how my brother and I grew up in the same house but ended up with totally different careers and lifestyles!
If you’re as fascinated by these eight-legged wonders as I’ve become, you can dig deeper at the World Spider Catalog, which lists all known spider species. It’s a web of information that’s sure to catch your interest!
