Many people associate tarantulas with earthy tones like brown or black. However, these fascinating arachnids exhibit a surprising array of colors that extend far beyond simple camouflage. This diversity in their appearance is a result of complex biological mechanisms and can change throughout their lives, revealing a more vibrant spectrum than commonly imagined.
Beyond the Brown: A Spectrum of Shades
While many tarantula species display shades of brown, black, or gray, a remarkable number showcase vibrant hues across their bodies. These can include striking iridescent blues, greens, purples, reds, oranges, and even metallic sheens. For instance, the Cobalt Blue tarantula (Cyriopagopus lividus) is known for its vivid blue legs, while the Green Bottle Blue tarantula (Chromatopelma cyaneopubescens) features bright blue legs, a metallic green carapace, and an orange abdomen. The Gooty Sapphire Ornamental (Poecilotheria metallica) displays metallic blue legs and a patterned body.
Other notable examples include the Mexican Redknee tarantula (Brachypelma smithi), recognized for its striking red and black coloration, and the Brazilian Blue tarantula (Lasiocyano sazimai), which can be entirely iridescent blue. The Antilles Pinktoe tarantula (Caribena versicolor) can transform from ruby red as a spiderling to blue and purple in adulthood. Some species, like the Pumpkin Patch tarantula, exhibit unique patterns of orange, black, and white.
The Science Behind Tarantula Colors
Tarantula coloration stems from two primary biological mechanisms: pigmentary colors and structural colors. Pigmentary colors are produced by chemical compounds, such as melanin, which typically result in shades of brown and black, and carotenoids, which can contribute to yellow hues. These pigments are deposited within the cuticle of their exoskeleton and absorb certain wavelengths of light while reflecting others.
Structural colors, conversely, arise not from pigments but from the physical interaction of light with microscopic structures on the tarantula’s hairs or exoskeleton. These nanostructures, which can take various forms like cylinders or floral patterns, scatter specific wavelengths of light, creating brilliant and often iridescent effects. Blue and green colors in tarantulas are predominantly structural, with the arrangement of these nanostructures determining the precise shade and brightness. Many tarantula blues are non-iridescent, meaning their color remains consistent regardless of the viewing angle, a trait that differs from the shifting colors seen in many birds or butterflies.
How Appearance Varies and Why
A tarantula’s appearance can vary due to external factors like lighting conditions and internal biological processes such as molting and age. Tarantulas are largely nocturnal, and bright white or blue light can cause them stress. Red light, however, is less disruptive as tarantulas are largely insensitive to this part of the spectrum, allowing for observation without disturbance.
Molting, the process where a tarantula sheds its old exoskeleton to grow, significantly impacts its color intensity. After a fresh molt, colors often appear brighter and more vibrant, gradually dulling or changing hue as the time approaches for the next molt. Age also plays a role, with many species exhibiting different colorations as juveniles compared to adults.
The diverse colorations also serve various ecological purposes. Green colors, for example, often assist arboreal (tree-dwelling) species in camouflage by allowing them to blend with foliage. Blue coloration may play a role in communication between potential mates, as tarantulas can perceive these tones. These colors contribute to their survival and reproductive strategies.