The Difference Between Tarantulas and Spiders: More Than Just Size
While all tarantulas are spiders, not all spiders are tarantulas. This seemingly simple statement highlights a crucial point: tarantulas belong to a specific family of spiders, Theraphosidae. Understanding the distinctions requires delving into their biology, behavior, and characteristics.
What Makes a Tarantula a Tarantula?
Tarantulas are characterized by several key features that set them apart from other spiders. These include:
- Size: This is the most immediately obvious difference. Most tarantulas are significantly larger than the average spider, with leg spans often reaching several inches, and some species exceeding 12 inches. However, size alone isn't a definitive characteristic; some very large spiders aren't tarantulas.
- Hairy bodies: Tarantulas are famously covered in dense hairs, or setae, which serve various functions, from sensory perception to defense (urticating hairs). While many spiders are hairy, the density and type of hair on tarantulas are distinctive.
- Chelicerae: These are the fangs, and in tarantulas, they are robust and powerful, capable of delivering a venomous bite. While all spiders have fangs, the size and structure of a tarantula's chelicerae are often proportionally larger.
- Behavior: Tarantulas are generally terrestrial and relatively slow-moving compared to many other spiders. Many are ambush predators, lying in wait for their prey. Their defensive mechanisms often involve urticating hairs, rather than speed or intricate webs.
Are All Big Spiders Tarantulas?
No. Many large spiders exist that are not tarantulas. Giant crab spiders, huntsman spiders, and certain species of wolf spiders can reach impressive sizes, but they possess distinct morphological and behavioral characteristics that differentiate them from tarantulas.
What About Venom? Are Tarantulas More Dangerous?
All spiders possess venom, but the toxicity varies greatly. While tarantula venom can be painful to humans, causing localized effects like swelling and pain, it is rarely medically significant or life-threatening. Many other spider species, like the black widow or brown recluse, possess venom that is far more dangerous. Therefore, venom toxicity is not a reliable way to distinguish tarantulas from other spiders.
How Do Tarantulas Build Their Webs (If at all)?
While many spiders are renowned for their intricate webs, tarantulas primarily use silk for creating burrows, lining their retreats, or wrapping their prey. Their webs, if constructed at all, are much less complex than those of orb-weaving or funnel-web spiders.
What are some common misconceptions about tarantulas?
Many people believe all tarantulas are aggressive and deadly. This is a misconception. Most tarantulas are docile creatures that will only bite as a last resort. They are more likely to employ defensive tactics like urticating hairs.
In conclusion, while the sheer size and hairy bodies of tarantulas are striking, several other characteristics, including chelicerae structure, behavior, and web-building habits, are needed for accurate identification. Focusing on these combined features provides a more accurate way to differentiate a tarantula from other impressive—but distinct—members of the spider family.
