Tarantulas are large, hairy spiders from the family Theraphosidae. Although often depicted as menacing, their bite is generally not dangerous to humans. A bite from most species is painful but not medically significant, rarely causing more discomfort than a typical bee sting. Fatalities from tarantula venom are extremely rare, setting them apart from spiders like the black widow or brown recluse.
The Nature of Tarantula Venom
Tarantulas are reluctant to bite, reserving their venom primarily for immobilizing and predigesting prey, such as insects and small rodents. The venom is a mixture of proteins and peptides, including neurotoxins and enzymes, but its potency against humans is very low across most species, especially New World tarantulas. A bite typically results in immediate, localized symptoms, such as sharp pain, redness, and swelling at the site. Systemic symptoms are uncommon, though some individuals may experience mild muscle cramping, nausea, or headache. Severe reactions are limited to people with a rare, pre-existing allergy to the venom’s proteins, which can lead to anaphylaxis.
The Threat of Urticating Hairs
For many species, particularly New World tarantulas, the primary defense mechanism is specialized, barbed structures called urticating hairs. These spiders rapidly rub or “flick” the hairs from their abdomen using their legs, directing a cloud toward a perceived predator. Once launched, the hairs embed themselves in the skin or mucous membranes due to their microscopic barbs, causing irritation.
Contact triggers an inflammatory response known as urticating dermatitis, characterized by severe localized itching, a persistent rash, and sometimes hive-like bumps. The most serious complications arise when the hairs penetrate sensitive areas, such as the eyes or the respiratory tract. Ocular exposure can lead to ophthalmia nodosa, where hairs lodged in the cornea or conjunctiva cause inflammation and potential vision problems. Inhaling the hairs can irritate the airways, leading to coughing or shortness of breath.
Immediate Response and Treatment
If a tarantula bite occurs, clean the wound thoroughly with soap and water to minimize the risk of bacterial infection. Applying a cool compress or ice pack helps reduce localized swelling and pain. Elevating the affected limb assists in managing swelling, and over-the-counter pain relievers can be used for persistent discomfort.
Treating Urticating Hairs
For exposure to urticating hairs, avoid rubbing the area, as this pushes the barbs deeper into the skin. A practical removal technique involves gently pressing and lifting adhesive tape onto the skin to pull out the embedded hairs. If the hairs enter the eyes, immediate and thorough flushing with cool water is necessary, followed by an urgent evaluation by a medical professional. Any sign of a severe allergic reaction, such as difficulty breathing or swelling of the face or throat, requires immediate emergency medical attention.