Spiny Orb-Weaver, Crab Spider, Spinybacked Orbweaver
Gasteracantha cancriformis
Araneidae (Orb-Weavers), Order Araneae
Physical Description
The body features a distinctively wide, flattened, hard, and leathery abdomen equipped with prominent, sharp spines along the margins. The cephalothorax is compact and dark, while females possess a remarkably broad abdominal shield adorned with six distinct spines.
Size Estimate
Females generally measure 5 to 9 mm in body length, but their wide spiny abdomens can span 10 to 13 mm across. Males are significantly smaller, measuring 2 to 3 mm.
Coloration & Markings
Coloration is highly variable. The abdominal background is commonly white or yellow with contrasting black spots, and the prominent marginal spines are usually black or red. Variations include orange and red morphs.
Web Type
Constructs a classic vertical orb web featuring a distinctive open hub and heavy sticky spiral lines, typically placed between shrubs, trees, or wooden structures.
Eye Arrangement
Typical araneid eye pattern consisting of eight eyes arranged in two rows, with four central median eyes and a lateral pair on each side.
Leg Characteristics
Legs are relatively short, stout, and dark, equipped with fine hairs and specialized claws for navigating the orb web without getting stuck.
Venom & Safety Information
Venom Information
Venom is specialized for subduing small insect prey and possesses negligible potency against humans.
Medical Significance
Harmless to humans. A bite may cause minor, temporary local discomfort similar to a mild ant sting, requiring no special medical attention.
Safety Recommendations
No special precautions needed. Simply appreciate them from a distance, or gently relocate them using a cup if found in an inconvenient location.
Habitat & Behavior
Habitat & Range
Found throughout the Americas, from the southern United States through Central America and the Caribbean to South America. Prefers woodland edges, gardens, and overgrown brush.
Behavior & Temperament
Docile and non-aggressive. They spend most of their time stationary at the center of their webs waiting for prey and will drop to the ground if heavily disturbed.
Diet & Prey
Primarily feeds on small flying insects such as flies, mosquitoes, small moths, and beetles intercepted by the vertical orb web.
Seasonal Activity
Most commonly seen during late summer and autumn when females reach full maturity and construct prominent webs.
Description
The Spiny Orb-Weaver is one of the most visually striking and easily recognizable garden spiders due to its crab-like, brightly colored, spiny abdomen. Perfectly harmless to humans, these master architects spin neat vertical webs to catch nuisance insects around yards and woodlands.
Key Features
Wide, crab-like flattened abdomen equipped with six distinct marginal spines and bright contrasting yellow and black markings.
Similar Species
Other species within the genus Gasteracantha found globally, distinguished primarily by regional distribution and spine positioning.
Life Cycle
Females lay eggs in a protective silk cocoon attached to leaves or bark in autumn, where the egg mass overwinters until spiderlings hatch in spring.
Ecological Importance
Acts as an effective natural pest control agent by consuming large quantities of flying insects in gardens and natural habitats.
Conservation Status
Secure and widespread throughout its natural geographic range with stable population trends.
Interesting Facts
The bright coloration of the spiny orb-weaver is believed to serve as aposematism, warning potential vertebrate predators that they are unpalatable or too spiny to swallow easily.
Photography Tips
Use a macro lens or a smartphone macro setting with a neutral background. Natural side lighting highlights the glossy texture and sharp spines of the abdomen best.
Identified: 2026-07-29T03:17:05.273731