Urticating hairs are a defense mechanism used by tarantulas. Urticating hairs are finely barbed and cause irritation when they come into contact with the skin, eyes or nose of potential predators. Tarantulas can kick these hairs off, creating a cloud of irritants if they feel threatened.
Not all tarantulas have urticating hairs. Urticating hairs are most commonly found on New World tarantulas – those from the Americas. However they are not found among Old World tarantulas such as those from Africa and Asia.
Where Are the Urticating Hairs Located?
Urticating hairs are most commonly seen on the abdomens of tarantulas. Many species of tarantula can scratch these off their abdomen using their rear legs. This is why some tarantulas develop a bald spot on their abdomen.
Whilst urticating hairs are most common on the abdomen, they may be found elsewhere on the body. In one species, for example, they are found around the front legs.
Why Do Only Some Tarantulas Have Urticating Hairs?
Tarantulas utilise a variety of survival techniques to avoid getting eaten or attacked in the wild. The production of urticating hairs is just one such method. Other examples can include being very fast moving, or being more willing to throw up a threat posture or to bite.
While urticating hairs have been demonised in the mainstream press as something tremendously bad, the reality is that many more docile tarantulas use this defence strategy.
Many common pet tarantulas such as Curly Haired tarantulas and Mexican Red Knees possess them. Fortunately, these species tend to be reasonably docile and slow-moving, making them ideal pets if you avoid the urticating hairs.
How Are Urticating Hairs Used?
Urticating hairs may be used in a variety of ways. Possibly the best-known is kicking or combing them off the abdomen with the rear legs. Here they produce an irritating cloud that can scare off potential predators.
However this is only one way in which urticating hairs may be used by tarantulas. If captured, some tarantulas may press their abdomen against the skin of the predator, pushing their urticating hairs deep into the epidermis.
Urticating hairs may also be used to provide protection when moulting. Tarantulas often spin a neat mat of web on which they moult. There is evidence that some species may add urticating hairs to this webbing to dissuade predators from interfering.
This same method can be used when laying eggs, and the inclusion of urticating hairs in the silken eggsac may also offer some additional protection for the baby spiders growing within.
Do Urticating Hairs Grow Back?
Urticating hairs can grow back. However urticating hairs do not grow like human hairs.
It is not like plucking your eyebrows, only for the hairs to start growing back again soon afterwards.
Instead, urticating hairs are replaced when the tarantula moults. After a successful moult all the lost hairs will be replaced and the spider will look as good as new.
What Do Urticating Hairs Feel Like?
Urticating hairs are part and parcel of life for many tarantula owners. If they get onto the skin they can cause irritation. This often feels like an unpleasant itch, and the skin may become red and blotchy for a few days after tank maintenance.
The results can be more extreme if hairs are allowed to enter the eyes, nose or mouth. For this reason it is wise to keep your face well clear of your pet tarantula.
Some people also choose to wear protective gloves and long sleeves when carrying out tank maintenance to prevent getting urticating hairs on their skin.
Are All Urticating Hairs the Same?
There is surprising variety in urticating hairs. Not only are some tarantulas far more likely than others to kick off hairs, but the effect of these hairs can vary from species to species. For example, goliath birdeaters (Theraphosa spp.) are considered to have particularly unpleasant hairs.
Are Urticating Hairs Dangerous?
With some basic precautions urticating hairs should represent no serious risk to tarantula keepers.
Keep your face away from the spider itself and from the cage at all times. Avoid touching your face when maintaining your spider. Be sure to thoroughly wash your hands before and after carrying out any maintenance or any handling session.
If in doubt consider wearing protective gloves and long sleeves to reduce the chances of coming into contact with hairs.
In extreme cases you may want to consider wearing goggles and a mask though this is rarely necessary.
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