What you need to know about Urticating Hairs
Understanding Urticating Hairs: A Hidden Defense in Tarantulas
As many of you know, tarantulas come in two main categories: New World and Old World species. New World tarantulas are found in the Americas, while Old World tarantulas inhabit places like Africa and Asia. While we often focus on venom when talking about tarantulas, it’s actually the urticating hairs—especially in New World species—that should be getting more attention.
New World vs. Old World: The Basics
Old World tarantulas tend to be more defensive, faster to flee, and quicker to posture up when threatened. They also lack urticating hairs, but in return, they typically have stronger venom. However, the idea that Old World species always have stronger venom than New World species isn't scientifically proven—most of what we know comes from anecdotal evidence.
On the other hand, New World tarantulas, while often less defensive, have one powerful weapon in their arsenal: urticating hairs. These hairs, which they can kick into the air, act as an incredibly effective defense mechanism. When a predator gets too close, they kick up these hairs into the air, which can temporarily blind and irritate attackers, making them think twice about getting any closer.
What Are Urticating Hairs?
Urticating hairs are tiny, barbed hairs that New World tarantulas use for self-defense. They are found on different parts of their body, most commonly on the abdomen, and can be released into the air as a cloud, or rubbed onto surfaces like burrows, webs, and egg sacs. These hairs are highly irritating to predators like birds, reptiles, and small mammals.
Interestingly, around 90% of New World tarantulas have these hairs, though some species like Psalmopeous are an exception. Not all urticating hairs are created equal. There are actually seven distinct types, each with unique characteristics, and they are often used to differentiate species from one another.
Types of Urticating Hairs
Type I: Small but effective, these hairs measure 0.2-0.6mm and are found in species like Nhandu, Proshapalopus, and Vitalious. They are great for kicking into the air or applying directly to webs for passive defense.
Type II: A little larger, these hairs measure 0.5-1.5mm and are found in species like Avicularia, Pachistopelma, and Iridopelma. These hairs aren't kicked into the air; instead, the tarantula rubs them onto the surface or the person they feel threatened by.
Type III: These are larger (0.3-1.8mm) and among the most irritating to humans and animals alike. Found in species like Nhandu and Brachypelma, they are highly effective when kicked into the air.
Type IV: These hairs are fine and small, usually around 0.06-0.2mm, and are embedded with a penetrating tip. They are found in species like Grammostola and Euathlus and are less irritating to humans, but still highly effective against smaller predators.
Type V: Short, light, and embedded in hair follicles, these hairs are unique to the Ephebopus genus. They don't penetrate the skin but can still cause irritation when in contact.
Type VI: Rare and found in the Hemirrhagus species, these hairs are also embedded in the hair follicle.
Type VII: The most recently discovered type of hair, described in 2016, these are exclusive to the Colombian Kankuamo tarantula and are equipped with reversed barbs for extra irritation.
The Irritating Effects of Urticating Hairs
If you've ever had urticating hairs come in contact with your skin, you know they can be extremely uncomfortable. While many people joke about the hairs or think they're no big deal, they can cause a variety of issues, from itching to rashes, bumps, and even blisters in some cases. For species with particularly strong hairs, such as the Theraphosa genus, the effects can last for days.
Personally, I find Theraphosa hairs to be the most irritating. I’ll often get small bumps on the affected area, and the itching can last for two or three days. That’s why I wear rubber dishwashing gloves whenever I handle species like Theraphosa to avoid any issues.
Building a Tolerance?
There’s a common myth that you can build up a tolerance to urticating hairs over time. Unfortunately, that’s not the case. The more you're exposed to them, the worse the reaction can get. In fact, I’ve spoken to people who can no longer even be in the same room with certain species because the discomfort has become intolerable. That’s why it’s so important to take precautions, even if you don’t feel much irritation at first.
Precautions and Prevention
If you're rehousing your tarantulas or interacting with them in any way, it’s essential to take the proper precautions to avoid getting urticating hairs on your skin or in your eyes. Some basic measures include wearing gloves, long sleeves, eye protection, and even a face mask for particularly hairy species. I always recommend washing your hands immediately after handling New World species to avoid transferring the hairs.
It’s also important to turn off any fans or close windows when working with species that are particularly prone to kicking up hairs. A fan can quickly blow the hairs onto you, which can turn a simple interaction into a very itchy situation.
Final Thoughts
While it’s easy to get caught up in the fascination with tarantula venom, the true danger often lies in those tiny, irritating hairs. If you're a tarantula keeper, it’s important to respect these creatures' defensive mechanisms and take proper precautions. Whether you're new to the hobby or a seasoned keeper, understanding urticating hairs and how to handle them can make your tarantula keeping experience much more enjoyable and comfortable.
