Tan Jumping Spider, Flatties
Platycryptus undatus
Salticidae (Jumping Spiders), Order Araneae. Key family characteristics include exceptionally large anterior median eyes for acute stereoscopic vision, robust bodies adapted for leaping, and specialized adhesive hairs on the tarsi for climbing smooth surfaces.
Physical Description
The spider has a compact, flattened body shape with a robust cephalothorax and an oval-to-elongate abdomen. The body is covered in fine, dense setae giving it a velvety appearance. Distinct sexual dimorphism exists, with males often showing more contrasting markings and elongated chelicerae, while females are slightly larger and duller in coloration.
Size Estimate
Body length typically ranges from 8 to 13 millimeters for females and 7 to 10 millimeters for males, with a leg span proportional to the body. The specimen in the image appears to be a medium-sized adult or a well-developed juvenile.
Coloration & Markings
Base coloration is grayish-brown to tan, featuring mottled patterns of darker brown, black, and whitish-grey scales. The abdomen often displays a series of wavy chevron or banded patterns running down the dorsal side, which provides excellent camouflage against tree bark.
Web Type
Does not build a web to catch prey. Instead, it constructs a silken retreat (a flattened sac) under loose bark, in crevices, or on rough walls, used for molting, sleeping, and egg-laying.
Eye Arrangement
Arranged in three rows characteristic of jumping spiders: a prominent front row of four forward-facing eyes with massive central lenses for high-resolution color vision, and two smaller eyes on top and behind the cephalothorax.
Leg Characteristics
Legs are relatively short, thick, and powerful, adapted for sudden leaps rather than running. They often feature distinct dark and light banding patterns and are held close to the body in a compact stance.
Venom & Safety Information
Venom Information
Contains mild neurotoxic venom used primarily to immobilize small invertebrate prey. It poses no chemical threat to humans.
Medical Significance
Harmless to humans. Bites are extremely rare and typically only occur if the spider is squeezed or pressed directly against the skin. Symptoms are generally limited to minor, transient localized pain and slight redness, akin to a mild mosquito bite.
Safety Recommendations
No special precautions needed as they are completely harmless. If one is found inside and needs to be moved, gently place a cup over the spider, slide a piece of paper underneath, and release it outdoors.
Habitat & Behavior
Habitat & Range
Found widely across eastern North America, frequently inhabiting deciduous forests, woodlands, and human-made structures such as wooden fences, stone walls, and the exterior of buildings where they bask in the sun.
Behavior & Temperament
Diurnal, active hunter with incredible jumping ability. They are notably curious, often turning to face human observers. They possess a docile temperament and will only bite if handled roughly or trapped against the skin.
Diet & Prey
Carnivorous generalist feeding on a wide variety of small insects, including flies, mosquitoes, moths, and other spiders. They stalk prey patiently before launching a rapid, calculated leap.
Seasonal Activity
Most active during spring, summer, and early autumn when temperatures are warm. They overwinter as juveniles or adults by seeking shelter in silken hibernacula tucked into protective crevices.
Description
The Tan Jumping Spider is a charismatic and familiar visitor to wooden fences and building walls across its range. With its flattened profile and exceptional vision, it is perfectly adapted for hunting on vertical surfaces. Lacking a traditional web, it relies on stalking and an explosive leap to capture prey, making it a welcome and harmless guest in gardens and around homes.
Key Features
Flattened body profile, characteristic large forward-facing eyes, mottled tan and gray chevron patterns, and a distinctly robust, leaping stance.
Similar Species
Other medium-sized jumping spiders such as Platycryptus californicus in the west, or members of the genus Phidippus, though Phidippus species tend to be much stockier, hairier, and often feature bright metallic coloration on their chelicerae.
Life Cycle
Females construct silken egg sacs containing dozens of eggs within protected crevices, guarding them until they hatch. Spiderlings go through multiple molts as they grow, achieving adulthood within a year. Lifespan is typically around one to two years.
Ecological Importance
Serves as an effective, natural pest control agent by actively hunting and reducing populations of small insects around homes and gardens without the use of chemical pesticides.
Conservation Status
Not evaluated by the IUCN, but populations are secure, widespread, and highly adaptable to human-altered environments.
Interesting Facts
Tan jumping spiders can leap up to several times their own body length using a sudden hydraulic pressure change in their legs. They can also see in color, including the ultraviolet spectrum.
Photography Tips
Use a macro lens to capture the detailed eye arrangement and facial features. Shoot from a low angle during daylight hours when natural light is abundant to highlight the fine textured setae.
Identified: 2026-10-01T01:26:18.816005