Scorpions are ancient predatory arachnids recognized by their distinct appearance: large pincers, four pairs of walking legs, and a segmented tail ending in a venomous stinger. They have successfully colonized nearly every terrestrial environment, adapting to diverse climates from deserts to rainforests. Their secretive, nocturnal habits often lead people to associate them solely with the ground, hiding beneath rocks or in burrows. This common perception raises the question of whether any species defy this ground-dwelling expectation by making their home in trees.
Scorpion Habitats: The Terrestrial Majority
The vast majority of the approximately 2,500 described scorpion species are terrestrial, spending their lives on or beneath the ground. These scorpions thrive in a wide range of habitats, including arid deserts, temperate grasslands, and humid forest floors. Their behavior is driven by the need to regulate body temperature and conserve moisture.
During the heat of the day, these scorpions seek refuge in microhabitats that offer cooler, stable conditions. They frequently hide under rocks, fallen logs, leaf litter, or debris. Many species are expert burrowers, digging retreats that can extend a meter or more deep to find suitable moisture and temperature. This deep burrowing behavior is typical of most desert-adapted scorpions.
Arboreal Scorpions: Species That Live In and On Trees
A select group of scorpions are considered truly or semi-arboreal, choosing to live on vertical surfaces like trees and bushes. These species have specialized their behavior and morphology to exploit the resources and shelter found above the ground. Arboreal scorpions are closely associated with the bark of trees, using it for shelter rather than dwelling in the open canopy.
The Arizona Bark Scorpion (Centruroides sculpturatus or Centruroides exilicauda), found in the southwestern United States and Mexico, is the most well-known arboreal example in North America. This species spends its days hiding in crevices and beneath the loose bark of trees and palms. Other genera, such as Tityus and additional Centruroides species, also contain arboreal representatives, particularly in tropical regions. These scorpions often aggregate in large groups beneath bark for overwintering or daytime shelter, sometimes numbering up to 30 individuals.
Adaptations for Climbing and Bark Shelter
The ability of these scorpions to climb vertical surfaces is due to specific physical adaptations on their legs. Unlike many terrestrial species, arboreal scorpions possess specialized structures on their tarsi, the last segments of their legs. These structures include curved claws and stout, spinelike setae, which provide a strong grip on rough surfaces like bark and rock.
Scorpions climb for multiple survival reasons beyond seeking permanent shelter. Moving up trees helps them avoid ground-level predators and floodwaters, while also allowing access to a different hunting zone. The space beneath loose, exfoliating bark offers a narrow, dark, and often humid microclimate that provides protection from the sun and temperature extremes. This combination of physical tools and adaptive behaviors allows these species to successfully exploit the vertical world of trees.