Spiders are an abundant and widespread group of arthropods, inhabiting nearly every terrestrial ecosystem. Their numbers and nutritional content make them a significant food source within various food webs. As both predators and prey, spiders play a substantial role in maintaining ecological balance, supporting a diverse array of animals.
Arthropod Predators
Many arthropods actively hunt and consume spiders, employing diverse and often specialized strategies. Spider wasps, belonging to the family Pompilidae, are notable predators that paralyze spiders to provision their nests. A female wasp stings a spider, paralyzing it, then drags it to a nest chamber (e.g., burrow, mud cell, crevice) where she lays an egg on it, providing food for the developing larva. Some species, like those in the genus Auplopus, may even snip off the spider’s legs to make transportation easier.
Other spiders also engage in araneophagy, preying on other spiders. This includes direct predation. Kleptoparasitism is another common interaction, where spiders steal prey from other spiders, often by residing in the host’s web. Some kleptoparasitic spiders are tiny and live directly within the webs of larger spiders, feeding on wrapped prey or even consuming prey too small for the host. This theft of resources can occur opportunistically or as an obligate behavior for certain species.
Avian Predators
Birds represent a significant group of spider predators, with many species regularly incorporating spiders into their diets. Insectivorous birds favor spiders, a rich source of protein and nutrients, especially crucial during breeding and migration. Warblers, such as the Worm-eating Warbler, frequently glean spiders from foliage and tree bark. Wrens, known for their energetic movements, actively search for spiders in dense vegetation, cracks, and crevices.
Sparrows and robins are also common spider eaters, foraging on the ground or within shrubs and trees. Black-capped chickadees often inspect tree bark and foliage for hidden arachnids. Other birds, including bluebirds, owls, vireos, cuckoos, gnatcatchers, creepers, kinglets, swallows, and flycatchers, also consume spiders. Birds employ various hunting techniques, such as plucking spiders directly from webs, catching them in mid-air, or snatching them from the ground. Spiders provide a notable amount of taurine, an amino acid beneficial for the brain development and overall health of young birds.
Reptile and Amphibian Predators
Cold-blooded vertebrates, including various reptiles and amphibians, also prey on spiders. Lizards like geckos and anoles consume spiders as part of their insectivorous diets. These agile hunters often use active foraging strategies, spotting spiders on surfaces and quickly capturing them. Spiders provide a readily available food source in many habitats where these reptiles reside.
Amphibians like frogs, toads, and salamanders regularly include spiders in their diet. Frogs and toads are opportunistic feeders, using their sticky tongues to snatch any moving prey that fits into their mouths. Salamanders, which are primarily carnivorous, consume a variety of small invertebrates, including spiders, especially terrestrial species. The venom of spiders typically poses no threat to amphibians, as it is a protein that is safely digested in their stomachs, rather than injected into their bloodstream.
Mammalian and Other Predators
Certain mammals and other animals opportunistically feed on spiders. Small mammals, like shrews and some rodents, consume spiders during foraging. These animals often have broad diets that include various invertebrates. Small carnivores might also occasionally prey on spiders, adding them to their diverse menu when available.
Beyond terrestrial animals, some aquatic environments support predators that consume spiders. Certain fish species prey on semi-aquatic or aquatic spiders near the water’s edge. Larger invertebrates, such as centipedes, also capture and consume spiders. These instances highlight spiders’ widespread role as a food source across various ecosystems and taxonomic groups.