Sicarius gracilis is a South American member of the six‑eyed sand spiders, belonging to the family Sicariidae. It inhabits dry, sandy regions where it buries itself just beneath the surface, camouflaging with grains of sand that cling to its flattened body. This stealthy lifestyle allows it to ambush unsuspecting prey while remaining nearly invisible to predators.
 
Physically, the species is notable for its crab‑like stance and six eyes arranged in three pairs, unlike the eight‑eyed arrangement typical of most spiders. Adults can reach body lengths of around 25–50 mm, with long legs adapted for quick bursts of movement across loose substrates. Their coloration blends seamlessly with their environment, enhancing their ability to remain concealed.
 
Although rarely encountered, Sicarius gracilis possesses strong venom and is not recommended for novice keepers. Its reclusive nature means bites are extremely uncommon, but its potency places it firmly among the more formidable arachnids.
 
Ecologically, S. gracilis plays the role of a patient ambush predator, feeding on insects and other small arthropods. Females construct camouflaged egg sacs by mixing silk with sand, ensuring their offspring remain protected. Like other members of the genus, they are thought to be long‑lived, with lifespans reaching over a decade. This combination of cryptic behavior, longevity, and formidable venom makes Sicarius gracilis one of the more mysterious and fascinating spiders of South America.