Body segments
The cephalothorax houses the eyes, brain, mouthparts, and the bases of the legs. The abdomen contains the heart, digestive tract, reproductive organs, silk glands, and spinnerets at the rear.
Spiders lack antennae. Sensory input comes from specialized hairs (setae), slit sensilla, and the eyes - typically eight, though arrangement varies by family and is a key identification trait.
Chelicerae and venom
All but one family (Uloboridae) possess venom glands connected to the chelicerae. The fangs articulate either downward (Mygalomorphae - tarantulas) or pinching together (Araneomorphae - most familiar spiders).
References
- [1]Spider Biology - American Arachnological Society. Accessed June 2026.
Related in Biology
- Spider silk and web typesAll spiders produce silk, but not all build webs.
- Spider life cycle and reproductionSpiders develop through egg, spiderling, and adult stages.
- Spider vision and sensesMost spiders have poor vision and rely on vibration and touch.
- Spider respiration: book lungs and tracheaeSpiders breathe through book lungs, tracheae, or both, depending on lineage.
- Molting and growthSpiders grow by molting their exoskeleton.
- Spider venom compositionSpider venoms are complex cocktails of peptides, enzymes, and low-molecular-weight compounds.