Spiders possess a unique and intriguing biology, particularly concerning how they consume food. Spiders do not possess a typical mouth structure with teeth and a tongue as mammals do. Their feeding mechanism is a specialized adaptation that enables them to process their prey in a distinctive manner.
Spider Oral Structures
Spiders do not have a traditional mouth with teeth and a tongue for chewing and swallowing solid food. Instead, their feeding apparatus is composed of specialized structures.
The most prominent of these are the chelicerae, which are essentially the spider’s jaws, located at the front of their cephalothorax. These appendages are crucial for biting and holding onto prey. Each chelicera is tipped with a fang, which is often hollow and connected to venom glands. These fangs act as natural injection needles, allowing the spider to inject venom into its prey to immobilize it. The fangs’ curved, conical shape is well-suited for piercing the exoskeletons of insects and holding prey in place.
Located near the chelicerae are the pedipalps, which are leg-like appendages that assist in feeding. Pedipalps are used for sensing the environment, manipulating food, and in some species, even helping to hold prey. Behind the chelicerae and other mouthparts, such as the labium and labrum, lies a hidden “mouth” or pre-oral cavity. This cavity is where digestive fluids are applied to the prey and from which the liquefied food is sucked.
The Process of External Digestion
Spiders employ a process called external digestion, which means they break down their food outside their body before ingesting it. Once prey is captured, the spider injects venom, which can also contain digestive enzymes, into the victim. These enzymes begin to break down the prey’s internal tissues.
After injecting enzymes, the spider regurgitates digestive fluids over and into its prey, turning the internal tissues into a liquid consistency. This chemical breakdown, sometimes aided by the crushing action of the chelicerae, reduces the prey’s body to a digestible fluid. The spider then uses a muscular sucking stomach to draw this liquefied meal into its body.
The pumping stomach creates a sucking motion to ingest the liquid food, leaving behind the indigestible hard parts, such as the exoskeleton. Spiders do not chew or swallow solid food in the way humans do. Their diet primarily consists of insects and other arthropods like flies, mosquitoes, and beetles, though larger spiders may consume small vertebrates such as frogs or lizards. Some spiders can go for weeks without eating due to their ability to slow their metabolism.