Tan Jumping Spider, Flattied Jumping Spider
Platycryptus undatus
Salticidae (Jumping Spiders), Order Araneae. Key family characteristics include large, forward-facing anterior median eyes providing exceptional stereoscopic vision, and specialized legs for jumping rather than running.
Physical Description
The spider has a compact, robust body with a somewhat flattened cephalothorax and abdomen. It is covered in fine, dense setae (hairs) that give it a textured, velvety appearance. Sexual dimorphism is present, with females typically larger and displaying lighter, more muted gray and brown tones, while males possess distinctive white facial hair and banded legs.
Size Estimate
Body length ranges from 8 to 13 millimeters (approximately 0.3 to 0.5 inches) with a leg span proportional to a compact jumper. The pictured specimen appears to be an adult or sub-adult.
Coloration & Markings
Patterned with mottled shades of gray, brown, tan, and black, providing excellent camouflage against tree bark and weathered wood. Wavy transverse bands and chevrons run across the dorsal abdomen.
Web Type
Jumping spiders do not spin webs to catch prey. Instead, they construct small, silk retreat sacs under loose bark, in crevices, or on siding where they rest, molt, and lay eggs.
Eye Arrangement
Arranged in three rows characteristic of Salticidae: a front row of four eyes with massive, highly expressive anterior median eyes in the center, flanked by smaller lateral eyes, and two smaller eyes set back on the cephalothorax.
Leg Characteristics
The legs are relatively short, stout, and powerful, adapted for sudden, explosive leaps. They feature distinct dark and light banding and are well-equipped with scopulae (dense hair tufts) for gripping smooth surfaces.
Venom & Safety Information
Venom Information
Contains neurotoxic venom used strictly to subdue small insect prey. It has virtually no effect on humans and is not medically significant.
Medical Significance
Completely harmless to humans. Bites are extremely rare, usually occurring only if the spider is forcefully squeezed against the skin, and result in minor, transient local irritation comparable to a mild mosquito bite.
Safety Recommendations
No special safety measures are required as they are completely harmless. If relocation is desired, gently guide the spider into a small container using a piece of paper.
Habitat & Behavior
Habitat & Range
Found widely across eastern North America. They frequent vertical wooden surfaces, including tree trunks, wooden fences, and the exterior walls of houses and buildings, favoring sunny exposures.
Behavior & Temperament
Active diurnal hunters that rely on acute eyesight to stalk and pounce on prey. They are docile, curious, and notoriously inquisitive toward humans, posing virtually no threat and often retreating rather than biting.
Diet & Prey
Carnivorous predators feeding on a wide variety of small insects, including flies, mosquitoes, aphids, and other spiders. They stalk prey like a cat before executing a precise, rapid leap.
Seasonal Activity
Most active during spring and summer months during daylight hours. They overwintering by sheltering inside silken hibernation sacs tucked beneath loose bark or siding.
Description
The Tan Jumping Spider is a charismatic and beneficial arachnid commonly encountered on wooden structures and tree trunks. With its fuzzy appearance, large curious eyes, and impressive leaping agility, it is a favorite among nature enthusiasts and serves as a natural pest controller around homes and gardens.
Key Features
Flattened body profile, distinctive wavy gray and brown mottled camouflage pattern, stout banded legs, and enormous forward-facing median eyes.
Similar Species
Can be confused with other small brown jumping spiders in the genera Phidippus or Sitticus, but Platycryptus undatus is distinguished by its notably flattened body and lack of bright metallic or brightly colored spots.
Life Cycle
Females construct silken egg sacs in sheltered crevices during summer, guarding them until the spiderlings hatch. Young undergo multiple molts before reaching maturity, typically living for about one year.
Ecological Importance
Acts as an effective biological control agent by consuming large quantities of pest insects around human dwellings and natural environments, occupying a vital niche in terrestrial food webs.
Conservation Status
Not evaluated by the IUCN, but populations are secure, widespread, and common throughout their natural range.
Interesting Facts
Tan jumping spiders can jump up to 50 times their own body length by suddenly increasing the hemolymph pressure in their hind legs. They are also known to tilt their heads and watch humans observing them.
Photography Tips
Use a macro lens in bright natural daylight to capture the incredible detail of their large eyes and velvety body texture. Approach slowly from the front to capture their characteristic head-tilt.
Identified: 2026-08-05T15:53:24.162856