Spiders are predatory creatures with a unique approach to acquiring and consuming food. Their eating process differs significantly from many other animals, involving specialized hunting techniques and external digestion.
Capturing Prey
Spiders employ diverse strategies to secure meals, from intricate web construction to active hunting. Many species, like orb-weavers, build elaborate silk webs to passively trap unsuspecting prey. Orb webs feature radiating spokes and a sticky spiral designed to ensnare flying insects. Funnel-web spiders, conversely, construct funnel-shaped retreats with a flat sheet-like section, waiting to ambush prey by sensing vibrations. Other web types include tangled cobwebs, which capture wandering insects, and flat sheet webs, which catch falling prey.
Beyond web-building, many spider species are active hunters, relying on stealth and speed. Wolf and huntsman spiders, for example, possess excellent vision and stalk prey on the ground or foliage. Jumping spiders exhibit leaping abilities, using acute eyesight to spot prey before a precise jump. Trapdoor spiders construct burrows with hinged, silk-lined doors, ambushing passing insects.
Once captured, spiders use their chelicerae—mouthparts with fangs—to inject venom. This venom contains neurotoxins that rapidly immobilize or paralyze the prey. Some web-building spiders also wrap ensnared prey in silk to subdue and store it.
Digesting and Consuming Food
The consumption of food by spiders involves a process known as external digestion. Unlike most animals that chew and digest food internally, spiders cannot ingest solid food due to their narrow gut. After immobilizing their prey, spiders inject a cocktail of digestive enzymes into the victim’s body through their fangs or by regurgitating fluid onto its surface. These enzymes break down the internal tissues of the prey, liquefying them into a nutrient-rich “soup.”
The chelicerae, which house the fangs, play a dual role in this process. Beyond venom delivery, they help manipulate the prey, and in some species, they may also be used to mash or shred the prey’s body, further aiding the enzyme penetration. Once the prey’s insides are liquefied, the spider uses a specialized muscular organ called the “sucking stomach” to draw in the pre-digested fluid. This stomach acts as a powerful pump, creating suction to ingest the liquid meal.
Spiders periodically reflux the digestive fluids, pumping them back and forth between their gut and the prey, which ensures thorough mixing of enzymes and efficient liquefaction of tissues. After extracting the liquid nutrients, spiders discard the indigestible remains, often leaving behind a hollow exoskeleton or a small ball of residual matter. This unique method allows spiders to consume prey that might be significantly larger than their own mouthparts.