Free Spider Identifier by Photo —
What Spider Is This?

How to Identify Spiders — What the AI Looks For

When you upload a photo to our free spider identifier, the AI analyses the same visual features an arachnologist would examine. Understanding these features helps you take better photos and interpret your results more confidently.

Body Shape and Segments

All spiders have two main body segments: the cephalothorax (head + thorax fused) and the abdomen. The shape, size ratio, and pattern on the abdomen are among the most important identification clues. Some families have distinctive abdomen shapes — elongated, round, triangular, or spiky.

Leg Count, Length, and Pattern

Spiders always have eight legs (not six like insects). Leg length relative to body size, banding patterns, spines, and hair density all help narrow down the family. Long thin legs suggest cellar spiders; thick hairy legs suggest wolf spiders; front legs held up like a boxer suggest crab spiders.

Eye Arrangement

Spider eye patterns are highly diagnostic. Jumping spiders have two large front eyes giving a “cute” face. Wolf spiders have a row of four large eyes on top. Most web-building spiders have eight small eyes in two rows. A close-up photo showing the eye region dramatically improves accuracy.

Colour and Markings

Abdomen markings — spots, stripes, hourglass shapes, cross patterns — are key identifiers. The red hourglass on a black widow is iconic. Brown recluse spiders have a violin-shaped marking on the cephalothorax. However, markings vary within species and colour alone is never enough for a definitive ID.

Common Spiders and How to Identify Them

These are the spiders people most frequently upload to our identifier. Understanding their key features helps you provide better information and interpret your result.

Cellar Spider (Daddy Long-Legs)

Very long thin legs, small body, found in ceiling corners and basements. Builds loose irregular webs. Completely harmless despite myths about venom. One of the most common indoor spiders worldwide.

House Spider

Medium-sized brown spider with chevron markings on the abdomen. Builds funnel-shaped webs in corners and window frames. Common across Europe and North America. Harmless to humans.

Black Widow

Shiny black body with a red hourglass marking on the underside of the abdomen. Found in dark sheltered areas — woodpiles, sheds, outdoor furniture. Medically significant bite. Photograph from a safe distance only.

Brown Recluse

Uniform brown colour with a violin-shaped marking on the cephalothorax and six eyes in three pairs (not eight in two rows). Found in the central and southern United States. Not aggressive but bite can cause tissue damage. Often misidentified.

Garden Orb-Weaver

Large round abdomen with intricate patterns, often found in the centre of a classic circular web. Common in gardens during late summer and autumn. Completely harmless and beneficial for pest control.

Jumping Spider

Small, compact, furry spider with two large front eyes. Active during the day, often seen on walls and windows. Hops rather than walks. Harmless and often considered one of the “cutest” spiders. Very common indoors and outdoors.

Are Most Spiders Dangerous?

The vast majority of spiders are completely harmless to humans. Of the roughly 45,000 known spider species worldwide, only a small number have bites that are medically significant to humans. Most spiders cannot pierce human skin, and those that can typically cause only mild irritation comparable to a mosquito bite.

• Beneficial predators — spiders eat flies, mosquitoes, moths, and other pest insects. A single spider can consume hundreds of insects per year.
• Non-aggressive — spiders bite defensively, not offensively. They will almost always flee rather than attack.
• Region matters — dangerous species are geographically specific. Black widows are a concern in the Americas; funnel-webs in Australia; no medically significant species in the UK or most of Northern Europe.
• Misidentification is common — harmless house spiders are frequently mistaken for brown recluses or black widows. Our AI helps reduce this anxiety by providing evidence-based identification.

What to Do After Identifying Your Spider

Once you have your identification result, here is how to act on it:

• Harmless species — consider leaving it alone. It is controlling pests in your home or garden. If you prefer it outside, gently cup and release it.
• Common indoor species — reduce clutter, seal cracks, and remove webs to discourage recolonisation. No pesticide needed for individual spiders.
• Potentially venomous species — do not attempt to handle or kill it yourself. Contact a professional pest control service, especially if found indoors or near children’s areas.
• Spider bite — if bitten, clean the wound, apply a cold compress, and seek medical attention if you experience severe pain, spreading redness, muscle cramps, or difficulty breathing. Save the spider photo for medical staff.