The animal kingdom is home to uniquely fascinating and diverse species. However, their beauty can be exotic, controversial, and difficult to perceive for humans. Spiders are probably the clearest example of this antagonism: elegant, agile, and intelligent insects whose anatomies can be as attractive as they are creepy. More than 43,000 arachnid species identified on our planet vary in size, color, threat, and diet. However, only about 30 species are lethal to humans.

Life in isolation

Natural selection endowed spiders with different defensive abilities: the largest, in general, do not have powerful venom since they can attack prey for food and defense with their large fangs. In contrast, smaller spiders tend to have more potent venom to compensate for their unthreatening size.

In the United States, a spider species is feared by those who know it: the brown recluse. Even though its reputation as an extremely aggressive species is not true, its painful and life-threatening sting is very much so. They are found in the arid and desert regions of the southern United States and can be identified by their mustard color and characteristic dark brown fiddle-shaped patch on their back. According to the Missouri Department of Conservation, adults can measure up to 1 inch (2.5 cm) and live in warm, dry, and dark places such as attics, woodpiles, and wall openings.

Credit: Wikimedia CommonsDespite their notoriety, many feared species do not have a bad temper. A study published in 2014 in Science evaluated the behavior of black widows, subjecting them to stimuli of different intensities and recording their responses. The researchers found that only 2 percent of the specimens responded aggressively, even to strong stimuli; most ran away or pretended to be dead.

In the same way, the brown recluse does not exhibit aggressive or attacking behavior. Coyote Peterson, a wildlife expert, didactically explains the behavior of these spiders and even dares to let one walk on his hands, demonstrating that brown recluses only bite when they feel threatened — mostly when they feel pressure on their back. So, Coyote recommends staying calm if one of these little creatures has gotten tangled up in the old sweater we just put on. Ideally, you should gently try to remove the spider with a piece of paper or a jar. Don’t push or squash it desperately, as it may sting you.

A study published in 2002 evaluated the presence of a swarm of over 2,000 brown recluse spiders in a family home. The swarm inhabited the house for 10 years, and only one bite was recorded during that period. This evidences the peaceful nature of this species, although it is not because they are less dangerous.

Another study published in Hematology suggested that necrosis in brown recluse bites is accompanied by a weakened immune system. Two patients with recent brown recluse bites were studied, and it was found that the venom killed red blood cells as a reaction, also known as warm autoimmune anemia. Both patients were discharged from the hospital after being administered corticosteroids and a blood transfusion.

What happens if I get stung by a brown recluse?

According to experts, about 90 percent of recluse bites heal without intervention. But all bodies react differently to venom, so in about 10 percent of cases, the sting can result in infection or necrosis — the death of skin or muscle tissue. If you get a brown recluse bite, you should immediately wash it with soap and water and apply ice. Then go to a health center to receive appropriate care, according to MedlinePlus.

According to the Illinois Department of Public Health, a brown recluse sting looks like a bee’s. Often there are no symptoms, but a bite can cause fever, nausea, irritation in the surrounding area, tremors, and sharp pain in the affected area. Remember that in some cases, the venom could cause necrosis, so you must seek medical attention if you experience any of these symptoms after being bitten by any arachnid.