Spider biology
How spiders are built, how they sense the world, how they reproduce, and how they spin and use silk.
- Biology
Spider anatomy
Spiders (order Araneae) have two body segments - the cephalothorax (prosoma) and abdomen (opisthosoma) - connected by a narrow pedicel. They have eight legs, chelicerae bearing fangs, and a pair of pedipalps.
- Biology
Spider silk and web types
All spiders produce silk, but not all build webs. Silk is used for webs, draglines, egg sacs, sperm webs, and prey wrapping. Web architecture is a strong identification cue.
- Biology
Spider life cycle and reproduction
Spiders develop through egg, spiderling, and adult stages. Most temperate species live one year; mygalomorphs (tarantulas) may live 20+ years.
- Biology
Spider vision and senses
Most spiders have poor vision and rely on vibration and touch. The exception is the Salticidae (jumping spiders), which have the most acute vision known among invertebrates.
- Biology
Spider respiration: book lungs and tracheae
Spiders breathe through book lungs, tracheae, or both, depending on lineage. Mygalomorphs (tarantulas, trapdoor spiders) retain two pairs of book lungs; most araneomorphs have one pair plus a tracheal system.
- Biology
Molting and growth
Spiders grow by molting their exoskeleton. The number of molts to maturity varies by family and sex; males typically reach maturity after fewer molts than females and have shorter adult lifespans.
- Biology
Spider venom composition
Spider venoms are complex cocktails of peptides, enzymes, and low-molecular-weight compounds. Most are optimized for invertebrate prey; only a small fraction has meaningful effect on mammalian tissue.
- Biology
Spider classification and taxonomy
Order Araneae contains over 51,000 described species in roughly 135 families. The order splits into two main suborders: Mesothelae (a small relict group), and Opisthothelae, which contains Mygalomorphae (tarantulas and kin) and Araneomorphae (the vast majority of spiders).