Spiders are eight-legged arthropods belonging to the class Arachnida, which also includes scorpions and ticks. With over 53,000 described species, they represent one of the most diverse groups of predators on Earth, having adapted to nearly every terrestrial environment. Their success is due to their ability to produce silk, a versatile material used for capturing prey and protecting their eggs. This adaptability allows spiders to thrive in a vast range of habitats across the globe, with the sole exception being Antarctica.
Global Ecosystem Habitats
Spiders inhabit all major terrestrial biomes, demonstrating specialized adaptations to survive extreme conditions in deserts, rainforests, and alpine zones. In arid desert environments, some spiders use behavioral thermoregulation, residing in silk-lined burrows to escape intense surface heat. Conversely, spiders in lush forests capitalize on dense vegetation and high insect populations by building intricate webs across branches and foliage.
Aquatic and semi-aquatic habitats also host specialized species. The diving bell spider creates a silk dome underwater filled with air, which functions as a gill and a retreat. Fishing spiders, like Dolomedes, are found near streams, where they skim the water surface to hunt small fish and insects.
Microhabitats and Structural Living
A spider’s habitat is often defined by the specific architectural structure it uses for survival, known as its microhabitat. Web-building spiders utilize silk to create fixed trapping devices, with the web’s design determining the exact location.
Orb weavers construct spiral webs in open spaces between plants or structures to intercept flying insects. Tangle-web spiders, also known as cobweb spiders, spin three-dimensional meshes often positioned in sheltered corners and under eaves to snare crawling prey. Funnel-web spiders build sheet-like webs anchored to the ground or low vegetation, leading into a silken funnel where the spider waits to ambush prey.
Non-Web Hunters
Many spiders do not rely on webs for hunting, instead using specialized retreats for shelter. Wolf spiders are active hunters that live on the ground, seeking temporary shelter under rocks, logs, or leaf litter. Some wolf spider species and trapdoor spiders excavate silk-lined burrows in the soil, which serve as a permanent home and a base for ambush hunting. These burrows may be left open or capped with a hinged door of silk and soil, providing protection from predators and extreme weather.
Spiders in Human Environments
Spiders living in close association with humans are termed synanthropic species, having adapted to the stable, artificial environments provided by buildings. Indoor habitats offer a constant climate and reliable shelter, appealing to species that cannot survive harsh outdoor conditions. Common indoor species include the cellar spider, which thrives in basements and damp corners, and the common house spider, often found in wall voids.
These indoor residents benefit from the consistent availability of insect prey attracted to human dwellings. Outdoor structures like sheds, garages, and window frames also provide favorable microhabitats. These man-made structures mimic natural sheltered areas, offering cracks and crevices ideal for attaching webs or creating small retreats.