Many people encounter white or pale spiders and wonder about their identity and potential danger. While no single species is universally called “the white spider,” many exhibit white or light bodies. Their coloration often serves for camouflage or other survival strategies. This article explores various types of white spiders, their appearance, distinguishing features, and potential threat to humans.
Commonly Called White Spiders
Several spider families and species are commonly observed with predominantly white or very pale appearances. Among the most recognized are crab spiders, such as the goldenrod crab spider (Misumena vatia), known for its ability to change color to match its surroundings, often appearing white or yellow. The Caribbean crab spider is another example, often white or yellow with a red stripe. These spiders are often found in gardens and woodlands.
Sac spiders (family Clubionidae), like the yellow sac spider, appear pale, from yellowish-white to cream. These spiders are typically slender with cigar-shaped or slightly triangular abdomens. Ghost spiders (family Anyphaenidae) are also characterized by translucent, pale bodies, often cream-colored with light brown markings and spiny legs.
Certain jumping spiders (family Salticidae) are strikingly white. Some Phidippus species, like the “White Bahamas” morph of the regal jumping spider, exhibit significant white coloration. While the zebra jumping spider (Salticus scenicus) is named for its black-and-white stripes, its white markings are prominent. Orb-weavers (family Araneidae) like the white spinybacked orbweaver have bright white abdomens, often with dark spots or spines.
The Science Behind White Coloration
White coloration in many spiders results from specific biological mechanisms. One reason is the absence of dark pigments, allowing underlying tissues or structures to appear pale. Alternatively, some spiders possess specialized cells with white-reflecting pigments, such as guanine crystals. These crystals scatter and reflect light, creating a matte white appearance.
White coloration frequently serves as camouflage, helping spiders blend into their environment. Crab spiders, for example, change color from white to yellow over several days to match flowers where they ambush prey. This adaptation helps them remain undetected by unsuspecting insects. Some spiders also use white coloration for mimicry; certain orb-weavers resemble bird droppings to deter predators.
Distinguishing Features and Habitats
Identifying white spider species involves observing their unique physical characteristics and preferred environments. Body shape and size vary considerably. Crab spiders, for instance, have a wide, flattened, crab-like body with the first two pairs of legs often longer and held outstretched. Sac spiders tend to be more elongated with prominent spinnerets at the end of their abdomen. Ghost spiders are typically small to medium-sized with slender bodies and spiny legs.
Eye arrangement is another key identifier. Jumping spiders possess large, forward-facing eyes that provide excellent binocular vision for hunting. Other spiders may have smaller eyes arranged in two rows or scattered patterns.
The presence or absence of a web also helps differentiate species. Crab spiders and sac spiders are active hunters that do not build webs to capture prey, though sac spiders create silken retreats for shelter. Orb-weavers, as their name suggests, construct intricate circular webs.
White spiders are found in various habitats. Crab spiders are often found on flowers in gardens, meadows, and woodlands, ambushing pollinating insects. Sac spiders often reside indoors in homes, woodpiles, or wall cracks, or outdoors on foliage or under bark. Ghost spiders are elusive, found in gardens or hiding under transparent silk during the day.
Are White Spiders a Threat?
Most white or pale spiders encountered by the public are harmless to humans. All spiders possess venom to subdue prey, but the venom of most common white spiders is not medically significant for humans. Bites are typically minor, often causing localized irritation, redness, or mild pain comparable to a bee sting.
Even when a bite occurs, it is usually a defensive reaction, such as when a spider is trapped against the skin. Some sac spiders (Cheiracanthium species) are occasionally associated with more painful bites, resulting in a red bump or swelling. These bites are generally not life-threatening and typically heal within days to weeks. Overall, concern about danger from white spiders is largely unfounded, as most pose no serious threat.