Sicariidae

Sicariidae is a family of araneomorph spiders that includes venomous species known for their potent cytotoxic and hemolytic venoms. The family is characterized by the presence of six eyes, arranged in a semicircle, and a distinctive violin-shaped marking on their cephalothorax, a feature particularly prominent in the genus Loxosceles. The most well-known genera within this family are Loxosceles, commonly called recluse spiders or fiddle-backs, and Sicarius, known as assassin spiders.

Spiders in the Sicariidae family are typically found in dry, secluded areas. Loxosceles species are often found in human dwellings, hiding in dark, undisturbed places like closets, attics, and behind furniture, which contributes to their common name. Sicarius spiders are ground-dwelling and often camouflage themselves by burying themselves in sand or soil, making them difficult to spot.

The bite of a Sicariidae spider can lead to significant medical consequences. While many bites are asymptomatic or cause only minor irritation, some can result in loxoscelism, a condition characterized by necrotic skin lesions (tissue death) at the bite site. In rare cases, systemic effects can occur, including fever, chills, and even organ damage, though fatalities are uncommon. The venom contains enzymes such as sphingomyelinase D, which is believed to be responsible for the cytotoxic effects. Due to the potential severity of bites, medical attention is often recommended for suspected Sicariidae envenomations.