The term “rainbow spider” is not a formal scientific classification but a nickname for spiders with vibrant, multi-colored bodies. These arachnids display a dazzling array of colors that seem to change with every movement. This characteristic sets them apart from more commonly known spiders, sparking curiosity about their appearance and the origins of their brilliant hues.
The Australian Peacock Spider
The most famous spiders known by this nickname belong to the Maratus genus, commonly called the Australian Peacock Spider. Found in Australia’s savannas, grasslands, and scrub forests, these spiders are small, averaging just 0.15 inches in length. Despite their size, the males possess a fan-like flap on their abdomen adorned with intricate patterns of red, blue, orange, and green.
To attract a mate, the male peacock spider performs an elaborate courtship dance. He raises his third pair of legs and vibrates his abdomen to display the stunning colors of his fan. This ritual is important for mating, as an unimpressed female may sometimes attack or eat the courting male. They are harmless to humans, as their venom is only effective on their small insect prey.
The Science of Spider Iridescence
The vibrant coloration of these spiders is not due to pigments alone. Their rainbow-like shimmer is a result of structural coloration, which is produced by microscopic structures on the spider’s surface that interact with light. This differs from pigments, which absorb certain wavelengths of light and reflect others to create color.
These structures consist of specialized scales and hairs on the spider’s body. These microscopic elements are shaped and arranged to refract and scatter light waves. This process creates the iridescent effect, where the colors appear to change depending on the viewing angle. A similar effect can be seen in the shimmering colors of a soap bubble or on the surface of a CD.
Other Notable Rainbow-Hued Spiders
Iridescent spiders are not confined to Australia, as several other species exhibit similar rainbow-like colorations. One notable example is the Rainbow Jumping Spider (Siler semiglaucus), found across various regions in Asia. This spider displays a metallic sheen of blue, red, yellow, and gold across its body.
While also a jumping spider, its coloration presents differently from the peacock spider’s distinct abdominal fan. The Rainbow Jumping Spider’s iridescence covers a larger portion of its body, giving it a more uniform metallic look. The existence of these spiders demonstrates that structural coloration in arachnids has occurred in different forms across the globe.