Spiders, with their intricate webs and diverse forms, often spark curiosity about their coloration. The question of whether truly purple spiders exist is a common one, highlighting the varied palette across species. While many spiders appear in muted tones, some exhibit striking colors that challenge typical perceptions.
The Reality of Purple Spiders
Truly purple spiders, displaying a pigment-based purple, are exceptionally rare in nature. While some species exhibit iridescent blues or violets that might appear purple under certain lighting conditions, a pure purple color is not commonly found or scientifically recognized as a primary pigment in spiders. For instance, the Ecuadorian purple tarantula (Avicularia purpurea) is known for its intense purple-blue iridescence on its cephalothorax, legs, palps, and chelicerae. Other examples, like the Gooty Sapphire Tarantula, are bright blue due to nanostructures in their hair.
Perceptions of purple can often stem from the way light interacts with a spider’s surface or from misidentification. This results in hues that might lean towards violet or appear purple depending on the viewing angle, rather than being a consistent, pigment-derived purple. Some bold jumping spiders (Phidippus audax) have iridescent chelicerae that can appear metallic green, blue, or occasionally pink or purple.
How Spiders Get Their Diverse Colors
Spider coloration arises from two primary biological mechanisms: pigmentary colors and structural colors. Pigmentary colors involve the absorption of certain light wavelengths by chemical compounds, reflecting others to produce colors like reds, yellows, oranges, and browns. Spiders utilize pigments such as ommochromes, which can produce colors ranging from yellow to orange, red, and even black, and have been identified in species like the crab spider Misumena vatia for its color-changing abilities. Recent research also indicates that spiders use carotenoids to produce yellow, orange, and red hues, often acquired through their diet.
Structural colors, in contrast, result from the interaction of light with microscopic structures on the spider’s cuticle or specialized hairs. These structures, through processes like interference, diffraction, or scattering, reflect specific wavelengths of light, creating iridescent, metallic, or vibrant blues and greens. For example, the brilliant blue coloration of some tarantulas comes from nanostructures in their hair that reflect and bend light.
A Spectrum of Spider Colors
While pure purple is largely absent, the spider world showcases an impressive array of other vibrant colors. Peacock spiders (Maratus species) from Australia are renowned for their spectacular displays of iridescent blues, greens, reds, and oranges on their abdomens. These colors are often due to a combination of pigments for reds and creams, and nanostructures for the brilliant blues and violets. The males use these elaborate patterns during complex courtship dances to attract females.
Another example is the bold jumping spider (Phidippus audax), a North American species with iridescent green chelicerae that can sometimes show blue or even pinkish-purple tones. Their bodies are typically black with distinct white, yellow, or orange spots that often change to white as the spider matures. Crab spiders, such as Misumena vatia, demonstrate remarkable camouflage by changing their color between white and yellow to match their floral surroundings. This color change is a complex physiological process involving ommochrome pigments and can take several days to complete.