Spiders are amazing creatures that have fascinated humans for centuries. With over 47,000 known spider species, these eight-legged arthropods display incredible diversity in their appearances, behaviors, and habitats. One interesting question that often comes up regarding spiders is whether they have color vision and color preferences like humans do. In this article, we’ll explore what science tells us so far about if and how spiders see color.
Do Spiders Have Color Vision?
Research suggests that some spider species are capable of detecting color while others may only see in black and white. Spiders have simple eyes known as ocelli. Most spiders have six or eight ocelli, some have fewer, and some spiders are entirely blind. The ocelli contain light-sensitive cells but lack the types of photoreceptor cells that allow for color vision in more complex eyes. However, some jumping spiders and wolf spiders have been found to have good color vision despite having only ocelli.
In their front four eyes, jumping spiders have what are called retinular cells arranged in layers that allow them to see color. These specialized cells contain two types of photopigments that detect different wavelengths of light. This gives jumping spiders trichromatic color vision similar to that of humans and some other mammals. Jumping spiders have been shown through experiments to be able to distinguish colors and have good color discrimination.
Wolf spiders also appear capable of color vision, though not to the same extent as jumping spiders. Research has found they can discriminate between different wavelengths of light beyond just blue and green. Exactly how they detect color is still being studied.
Do Spiders Have Color Preferences?
Spiders that can see color appear to have preferences for certain colors when hunting for prey or choosing mates. Here are some of the color preferences that have been observed in different spider species:
Jumping Spiders
- Bright reds, oranges, and yellows – jumping spiders are often attracted to prey and mates that are these colors.
- Black – they avoid black which may indicate a spider of the same species and potential threat.
- Blue – some jumping spiders display blue color patches, suggesting it may be an attractive color to potential mates.
Wolf Spiders
- UV white – wolf spiders are drawn to UV bright markings on their spider prey which are visible to them though not to humans.
- Green – female wolf spiders have shown preference for UV-green male decorations during mating.
Orb-weaver Spiders
- Yellows – many orb-weavers have yellow and yellow-orange in their body colors and webs, suggesting the color attracts prey.
- UV white – the patterns in orb-weaver webs reflect UV light, which attracts flying insect prey.
How Do Spiders Detect Color?
As mentioned earlier, most spiders detect light and motion with their many single-lensed ocelli. These ocelli allow spiders to navigate through their environment and detect prey movement but provide limited image forming capabilities. However, some species have more complex vision.
Jumping Spiders
Jumping spiders belong to the family Salticidae in the Araneae spider order. In addition to their four front ocelli, most jumping spiders have four rear ocelli. The front median pair of ocelli have developed specialized fovea that allows for detailed color vision. These ocelli have four different layers of light-sensitive retinular cells that contain two types of photopigments that detect different light wavelengths.
This retinal arrangement gives jumping spiders both motion detection from UV light as well as color discrimination across the visible light spectrum, similar to human trichromatic vision but based on a different mechanism. The rods and cones in human retinas allow us to see different colors based on the photopigments they contain. Jumping spiders instead see color using the filtering and focusing effects of the different retinular cell layers.
Wolf Spiders
Wolf spiders belong to the Lycosidae family. They have excellent eyesight like jumping spiders through their front median ocelli pair. Instead of a fovea, their specialized ocelli feature a band of light-sensitive receptors arranged horizontally across the retina. This rectangular-shaped area is optimized for detecting motion.
Research suggests this horizontal visual streak also enables wolf spiders to distinguish colors to some degree. The mechanism is not fully understood but may involve orthogonal filtering by the retina to allow wavelength discrimination. Though they see some color, wolf spiders appear to have vision that is driven more by movement and vibration signals.
Orb-weaver Spiders
Orb-weaver spiders like garden spiders spin large circular webs. Their vision is not as intricate as the hunting spiders with more complex eyes. But they do demonstrate some color preferences that involve UV light detection.
Many orb-weaving spiders have UV photoreceptors in their ocelli. This allows them to see in the ultraviolet spectrum, which their insect prey can also detect. The UV reflective patterns in their webs serve to attract insects. The bright yellow and yellow-orange colors on their bodies also signal UV lights to prey. So these spiders do exhibit visual preferences, likely through UV photoreceptors.
Do Male and Female Spiders Have Different Color Preferences?
Research shows that male and female spiders often prefer different colors when it comes to mating. The evolution of sexually dimorphic color patterns in certain species suggests the two sexes detect and select for different visual cues.
Jumping Spiders
Male jumping spiders often have bright red, orange, blue or green markings on their bodies. Females lack such bright decorations but prefer males with intense UV-blue patches which they find attractive.
Females also prefer males that exhibit courtship dances where they wave their decorative front legs. So motion in addition to color comes into play for mating choices.
Wolf Spiders
Male wolf spiders sometimes have black bodies with green or UV-green markings along the sides. Females are more cryptically brown or grey colored. When given a choice, female wolf spiders have shown preference for males with intensive UV-green decorations.
However, if the UV-green markings are too large, females will reject the males possibly because it signals lower fitness. So an optimal amount of decorative UV-green color is what attracts female wolf spiders.
Orb-weaver Spiders
Male and female orb-weaving spiders look somewhat similar to humans in their brown/black colors. But males have additional UV markings on their bodies that are visible to female spiders.
Research with Nephila orb-weavers showed that when UV light was blocked, the females were less receptive to mating with males. So these UV visual cues play an important role in sexual selection.
How Does Color Vision Help Spiders Survive?
The ability to see color provides key advantages for spiders in critical activities of hunting, avoiding predators, and finding mates. Here are some of the ways color vision helps certain spiders survive and thrive:
Finding Prey
- Jumping spiders can better spot colorful insects and other prey against varied backgrounds.
- Orb-weaving spiders use UV-reflective web patterns to target flying insect prey attracted to those markings.
- Wolf spiders identify camouflaged prey by looking for UV-bright markings.
Attracting Mates
- Male jumping spiders’ bright red and blue decorations attract female mates.
- UV-green markings on male wolf spiders signal fitness to female mates.
- UV body patterns on male orb-weavers entice female mates.
Avoiding Predators
- Jumping spiders can better spot the dark bodies of other threatening spiders of their kind.
- Camouflage coloration allows some spiders to blend into their surroundings and hide from predators.
- Bright warning colors may ward off some predators.
So while not all spiders have advanced color vision, those that do leverage it effectively for survival. Their unique visual systems provide key evolutionary advantages.
Do Spiders Use Color Vision in Navigation?
There is limited research on how spiders may use color vision specifically for navigation purposes. But a few potential ways color vision could aid navigation include:
- Jumping spiders may identify color landmarks to orient themselves in hunting territories.
- Brightly colored prey or mates could attract spiders from a distance.
- UV sun patterns could help with directionality.
- Color contrasts may help spiders spot structures and objects.
However, spiders appear to rely more on sensing vibrations, chemicals, and wind currents to navigate their environments rather than visual cues. Their multiple sets of ocelli seem adapted more for motion detection than color-based navigation. But having some color vision abilities likely provides additional environmental information to certain spiders as they move around.
Do Spiders Use Color Patterns to Camouflage Themselves?
Many species of spiders exhibit body colors and patterns that serve to camouflage themselves from potential prey and predators. Some examples include:
- Flower spiders have pink, white, yellow, or purple markings that blend in with petals.
- Crab spiders often are green or brown to match leaves and bark they perch on.
- Orb-weavers have black, yellow, and grey patterns that obscured in vegetation.
- Wolf spiders and grass spiders have bands and stripes that disguise their shape.
Research suggests camouflage coloration is not just for blending into the background but also for breaking up the spider’s outline. Disruptive patterns conceal the spider’s shape and make it harder to detect by prey and predators alike.
While camouflage indicates spiders have limited color vision, their cryptic colors serve an important protective purpose. Their ability to blend into the environment helps compensate for the vulnerability of being small creatures.
Do Spiders Change Color? Can They Fluoresce?
Some spiders demonstrate an incredible ability to change color for camouflage or signaling purposes. Here are a few examples of spiders with variable coloration:
Flower spiders
Flower spiders or crab spiders have an extraordinary skill – they can change their bodies to match the color of flowers they perch on. This chromatic mimicry helps them ambush pollinators that come to the flowers.
Research found the color change is prompted by visual cues rather than chemicals from the plants. When placed on different colored flowers, the spiders’ bodies underwent physiological color change to match within days.
Golden orb-weaving spiders
Female golden orb-weaving spiders have yellow and black patterns on their bodies. But when they are guarding egg sacs, their yellow pigmentation fades to white. This provides camouflage as they sit on their white egg casings.
The switch from yellow to white occurs slowly over a week’s time, likely triggered by hormonal changes related to becoming gravid (pregnant) and laying eggs.
Chameleon spiders
Not true chameleons, chameleon spiders have an extraordinary ability to change color to blend into their surroundings. Their translucent bodies have an upper layer of guanine crystals that can shift orientation to reflect different wavelengths of light.
Within a few days, these spiders can metamorphose between white, yellow, green, or brown based on the substrate they are placed on. It demonstrates both morphological and physiological color change in spiders.
Fluorescence
Some spiders also demonstrate fluorescence under UV light rather than color change. Scorpions glow an intense green/teal color under UV lamps. Spiderlings and some tarantulas also fluoresce bright blue.
The phenomenon is caused by metabolic compounds in the spider exoskeleton that absorb short wavelengths of light and re-emit it at longer wavelengths. The advantage of fluorescence is still unclear for spiders.
Conclusion
Research into spider vision and color perception is still an active area of study with much more to learn. But the evidence so far indicates some spider species have more advanced color vision than originally thought, despite their simple eye anatomy. Spiders with complex retinas like jumping spiders can see a full spectrum of colors much like humans do.
Color vision provides key benefits to spiders that possess it in terms of finding food, identifying mates, and self-preservation through camouflage. Bright colors and UV patterns play important behavioral roles in spider reproduction and predator avoidance.
While not all spiders have strong color discrimination abilities, those that do leverage it for better survival and mating outcomes. So in the spider world, color matters – at least for some species. Continued research will help uncover more about these unique creatures and how they see the world.