Spiders eat by first externally digesting their prey using powerful enzymes and mechanical action, turning it into a liquid that they can then consume.
Unlike most animals that chew and swallow solid food internally, spiders employ a unique feeding strategy. When a spider captures its prey, such as an insect, it doesn't immediately consume it in solid form. Instead, it uses a combination of chemicals and mechanical processes to break the prey down outside its body.
Here's a breakdown of the process:
- Enzyme Regurgitation: The spider regurgitates enzyme rich stomach fluids over and into its prey. These digestive enzymes, often working in conjunction with venom injected during the initial bite, begin the process of breaking down the prey's internal tissues.
- External Digestion: This chemical action constitutes external digestion. The enzymes dissolve the prey's body from the inside out and outside in, effectively predigesting the meal.
- Mechanical Processing: While the enzymes work, the spider often uses its mouthparts – including the fangs, toothed jaw bases, and maxillae – in a grinding, masticating action. This mechanical processing helps to further break down the prey's tissues and mix them with the digestive fluids.
- Creating the 'Soup': The combined action of chemical digestion and mechanical grinding reduces the prey's body and tissues to a liquid or semi-liquid state described as a chitinous soup. Chitin is the tough material that makes up the exoskeleton of insects and other arthropods.
- Consuming the Liquid: Once the prey has been liquefied, the spider uses its pumping stomach to suck up the nutrient-rich fluid. Only the indigestible exoskeleton is typically left behind.
This method allows spiders to consume prey that is often much larger than their mouth opening would normally permit, as they are effectively drinking their food.
Here's a simple overview of the stages:
| Stage | Action | Result |
|---|---|---|
| 1. Enzyme Application | Spider regurgitates stomach fluids with enzymes into prey | Initiates external digestion |
| 2. Mechanical Processing | Fangs, jaw bases, maxillae grind prey | Aids breakdown and mixing |
| 3. External Digestion | Enzymes and venom dissolve tissues outside the body | Prey body liquefies |
| 4. Consumption | Spider sucks up the liquid 'soup' | Nutrients are absorbed |
| 5. Remaining Parts (Often) | Indigestible exoskeleton is discarded | Waste product |
This efficient external digestion system is a key characteristic of spider feeding habits.
