Spider

Not insects

Spiders are arachnids — class Arachnida — with 8 legs, two body segments (cephalothorax and abdomen), and no antennae. Insects have 6 legs, three body segments, antennae, and (usually) wings.

Despite the difference, spiders are commonly grouped with “bugs” in popular usage and alphabet challenges. This collection includes them by that convention.

Web-building diversity

Spider web-building is one of the most studied animal architectures:

• Orb weavers — the classic radial spoke-and-spiral web (garden spiders).
• Cobweb weavers — chaotic 3D meshes (American house spider).
• Funnel-web weavers — tube webs with the spider waiting at the apex.
• Sheet weavers — flat horizontal webs above grass.
• Net-casting spiders — hold tiny nets between front legs and throw them at prey.
• Bolas spiders — swing a single sticky drop on a thread, mimicking moth pheromones.
• Jumping spiders — no web, ambush by leaping.
• Wolf spiders — chase prey on ground, no web.

Each technique represents millions of years of evolutionary refinement.

Silk superpower

Spider silk is among the strongest materials in nature:

• 5x the tensile strength of steel by weight
• Stretches 30%+ before breaking
• Hydrophilic — the water droplet bead pattern on dewy webs is captured rather than evaporated
• Self-disinfecting — silk surfaces resist microbial growth

A garden spider produces 6 different silks for different functions — frame thread (strong), spiral thread (sticky), egg-sac silk (dense), drag-line, attachment disks, and prey-wrapping. Each type has different protein composition.

Few are dangerous

Of 50,000+ spider species, fewer than 30 are medically significant to humans:

• Black widow — North American, neurotoxic.
• Brown recluse — North American, necrotic venom.
• Sydney funnel-web — Australian, potent neurotoxin (antivenom available).
• Brazilian wandering spider — South American, painful but rarely fatal.

Most spiders are harmless and beneficial — they eat enormous numbers of insects.

Worldwide population

A 2017 study estimated that spiders globally consume 400-800 million tons of insects per year — comparable in mass to the entire annual fish catch by humans, or to the total weight of all humans on Earth. Spiders are arguably the most important group of land predators by biomass impact.