Tan Jumping Spider, Flattied Jumping Spider
Platycryptus undatus
Salticidae (Jumping Spiders), Order Araneae
Physical Description
Flattened body profile designed for hiding in narrow crevices under bark, characterized by a robust cephalothorax and an elongated abdomen with distinctive scalloped or wavy markings.
Size Estimate
Body length typically ranges from 8 to 13 millimeters for females and slightly smaller for males, with a compact leg span proportionate to its body.
Coloration & Markings
Mottled shades of gray, tan, brown, and black providing excellent camouflage against tree bark and weathered wood, featuring a distinct wavy or scalloped pattern down the dorsal abdomen.
Web Type
Does not build a traditional web to catch prey; instead, constructs silken retreat sacs under loose bark or siding where it rests at night and during molting.
Eye Arrangement
Typical salticid arrangement featuring eight eyes in three rows, with two exceptionally large anterior median eyes that provide acute, forward-facing binocular vision.
Leg Characteristics
Short to medium, muscular legs designed for powerful leaps rather than running, often held in a flattened posture close to the body.
Venom & Safety Information
Venom Information
Possesses mild venom used strictly to immobilize small invertebrate prey, which is virtually harmless to humans and large animals.
Medical Significance
Not medically significant. Bites are extremely rare, non-toxic, and typically cause no more than minor, temporary local irritation similar to a mild mosquito bite.
Safety Recommendations
No special precautions needed as they are completely harmless; if removal is necessary, gently guide the spider into a cup using a piece of paper and release it outdoors.
Habitat & Behavior
Habitat & Range
Found throughout eastern North America, commonly inhabiting deciduous forests, woodlands, and the exterior walls of wooden buildings or fences where it hunts on vertical surfaces.
Behavior & Temperament
Active diurnal hunter relying on incredible vision to stalk and pounce on prey, remarkably curious towards humans and generally docile unless cornered.
Diet & Prey
Carnivorous predator feeding on a wide variety of small insects such as flies, gnats, ants, and other small spiders, overpowering them with a precise vertical leap.
Seasonal Activity
Most active during the warm spring and summer months, mating in early summer, and overwintering as juveniles or adults inside protected silken cocoons under bark.
Description
Platycryptus undatus, commonly known as the tan jumping spider, is a master of camouflage with a wonderfully flattened body and remarkable inquisitive intelligence. Easily recognized by its brownish-gray wavy patterns and oversized, expressive forward-facing eyes, this agile hunter navigates vertical wooden surfaces with confidence and precision. As a beneficial and completely harmless visitor to gardens and homes alike, it offers nature enthusiasts a delightful glimpse into the complex world of spider behavior and vision.
Key Features
Flattened body profile, prominent wavy or scalloped abdominal markings, gray-brown mottled coloration, and two huge forward-facing principal eyes.
Similar Species
Other gray or tan jumping spiders such as Platycryptus californicus in the west, or certain species in the genus Phidippus, which are typically more robust and less flattened.
Life Cycle
Females construct silken egg sacs in secluded crevices, guarding the eggs until they hatch into spiderlings that undergo multiple molts before reaching maturity.
Ecological Importance
Acts as an effective natural pest control agent by keeping populations of flies, mosquitoes, and other nuisance insects in check within gardens and around human habitations.
Conservation Status
Not threatened or endangered, maintaining widespread, stable populations throughout its natural geographic range.
Interesting Facts
Jumping spiders can leap up to 50 times their own body length using a sudden hydraulic pressure change in their legs, and they are capable of perceiving color in the ultraviolet spectrum.
Photography Tips
Approach slowly to avoid startling them, use macro lenses with natural side lighting to highlight eye texture and coloration, and shoot from a head-on angle to capture their expressive eyes.
Identified: 2026-09-03T23:42:43.016473