Small spiders, encompassing a variety of species such as common house spiders, jumping spiders, and crab spiders, are prevalent throughout diverse ecosystems. These arachnids, characterized by their consistently small adult size rather than being juvenile forms, play a significant role as predators in their environments. Their diet primarily consists of other small invertebrates, which helps regulate insect populations.
The Primary Diet
Small spiders primarily eat a range of small insects and other soft-bodied arthropods. Common prey includes flies (such as gnats and fruit flies), as well as mosquitoes, aphids, mites, small beetles, and moths. Spiders generally target prey that is smaller than themselves, often ranging from 50% to 80% of their own body size. While larger prey might offer more nutrition, it also presents a greater risk to the spider. Female spiders, which require more energy for egg development, may sometimes attempt to capture comparatively larger prey to maximize nutritional intake.
Hunting and Trapping Strategies
Small spiders employ diverse methods to secure their meals, broadly categorized into web-building and active hunting. Many species construct intricate silk webs that act as traps for unsuspecting prey. Orb-weaving spiders, for instance, create circular webs with sticky threads designed to ensnare flying insects. Sheet webs and tangle webs are other common web types, each strategically designed to capture prey that either flies into or crawls across the silken structure. Once an insect is caught, the spider detects vibrations in the web, quickly moving to immobilize its victim with silk and venom.
Other small spiders, known as active hunters, do not rely on webs for food capture. Jumping spiders, for example, possess keen eyesight and actively stalk their prey before pouncing. Crab spiders often camouflage themselves on flowers, ambushing insects like bees and flies that visit for nectar. After capture, spiders use external digestion: they inject venom, which often contains digestive enzymes, into the prey to paralyze it and begin liquefying its internal tissues. The spider then sucks up the liquefied contents, leaving behind the empty exoskeleton.
Beyond Insects: Dietary Nuances
While insects form the bulk of a small spider’s diet, certain species exhibit more varied feeding behaviors. Some small spiders might consume other small spiders, including their own kind, particularly when food is scarce. This behavior, known as cannibalism, can occur in various contexts, such as male spiders consuming females or juveniles eating siblings.
Some species also consume plant-derived products. Certain species, notably some jumping spiders, have been observed supplementing their diet with nectar or pollen from flowers. Nectar provides carbohydrates, while pollen offers proteins and other nutrients that might be difficult to obtain solely through insect predation. Spiders have even been observed to consume pollen caught in their webs. Furthermore, spiders obtain necessary water from dew droplets, moisture in their prey, or by absorbing environmental moisture through specialized body hairs.