Jumping Spiders

Spiders are among our most feared “bugs”, and this reputation is simply not deserved for many kinds. One of these is the Jumping Spiders – family Salticidae – which includes over 300 different species in the United States and Canada, and over 4000 species around the world. As spiders go they are considered to be some of the most “advanced” kinds, and have abandoned the need for webs to capture their food. Instead, they rely on excellent eyesight and the ability to run and jump quickly to capture their prey as hunters. Along with another group of hunting spiders, the Wolf Spiders, the jumping spiders often have a pair of enormous eyes positioned right in the front of their head, giving them the ability to see very well from several inches away. If you find one, and put your finger in front of it, you can watch the spider react to your presence by backing away, moving back and forth, and in general try to determine just what it is that has confronted it. Clearly, you are too big to eat, so are you friend or foe?

And, if you are content with playing this game of hide and seek with a jumping spider, do not be shocked if it calmly leaps onto your finger and wanders around on it without trying to harm you in any way. From a very young age my daughter was taught not to FEAR spiders, but to respect their ability to bite if threatened, and otherwise enjoy them. Perhaps this came from her many sessions with our pet tarantula, which has walked over the hands of thousands of school children without incident. The jumping spider has eyesight so well developed that it is one of the few spiders that detects objects without the need for movement by that object. Even a dead insect may become food for the foraging jumping spider.

All true spiders have venom and the fangs to deliver the venom to either enemy or food. Most kinds of spiders, however, are unable to bite people. Either their fangs are too small and weak to penetrate our skin, or the fangs are pointing in the wrong direction, and cannot extend out far enough to poke us. Of the kinds that are physically able to bite us the vast majority cause little to no harm to us. Either they choose not to inject venom with the bite, or the venom of that particular species just does not affect people and our metabolism. Jumping spiders fall into this second group. They could physically bite us, but they would not be considered dangerous. This does not mean that a particular person could not be very sensitive to the venom, and react in a manner that might require medical care, so any spider bite should be watched carefully to note your personal reaction. In fact, you might read some literature that states that jumping spiders are the most common culprits when a spider has bitten a person. Whether or not this is true would be difficult to prove.

Jumping spiders actually are fairly aggressive animals, not only in defense when they sense danger nearby, but also toward other jumping spiders. Males, in particular, often square off in battle mode, perhaps to lay claim to a female during mating season. The tough little male rears back slightly, raises the front pair of legs high in the air, and exposes his fangs to his competitor to show just how dangerous he would be. Quite often the physical battle begins, ending with one of the spiders bitten by the other and killed. Because they can see things fairly well, but perhaps not understand just what that “thing” is, a human finger intruding into their space could also be bitten. If you work in the garden it pays to wear gloves, just to keep the many crawly things off of you. If you actually are bitten by one do not panic. Since their venom is considered to be pretty non-life threatening you just need to keep an eye on it. Should you be someone whose immune system does not like insect stings or bites you probably already know, and should consult with your physician. Their venom is the same as nearly all spiders in North America, and it is a cytotoxic venom, meaning it might cause a small ulcerating sore. Keep the area clean and it will heal and go away.

It’s also unfortunate that spiders so often are BLAMED for causing sores on the skin of people, even if that person never actually saw a spider bite them. Many kinds of spiders have venom that affects the skin at the site of the bite, perhaps leading to a small sore that won’t heal quickly. According to some universities, however, it is likely that most of the time a spider has been blamed for such a skin disruption, the actual cause is a bacterial infection. But, by virtue of having been out in the garden, or stacking firewood, we recognize that we were in a position where spiders also could have been, and they become the fall guys. The only reason that a jumping spider – or nearly any spider for that matter – would bite a human would be purely in self defense. Since we are just too darned big to serve as spider food, they would bite only when they decide that their life is at risk due to being held in a hand or trapped in our clothing.

One of the most common jumping spider species in the U.S. is a lovely dark black one with white spots on top of its abdomen and white spotting on its legs. The scientific name for this spider is Phidippus audax, with common names varying – The Common Jumping Spider, the Daring Jumping Spider, the 3-Spotted Jumping Spider. It is large for this family of spiders, but even the biggest individuals are not more than one inch long with their legs stretched out. This is one of the prettiest jumping spiders, with that black and white contrasting coloring, and the males are blessed with beautiful shimmering, metallic green chelicerae, which are the coverings over their fangs. Since it is the male who needs to entice the female into mating he relies on convincing her of his worthiness by dancing before her with his colors there for her to admire.

The jumping spiders are very, very common visitors to structures, often being found on the exterior as they run around on the outside walls. As hunting spiders they do not spin webs for capturing food, but instead rely on excellent eyesight (excellent for a spider, that is) and rapid reflexes for capturing food on the run. Their huge, forward-facing eyes allow them to see things quite well from as much as a foot away, and they have even been observed to leap off an edge to try to capture an insect that was flying past them or that was resting on some other surface nearby. Their movements are erratic, and their running is more of a series of quick starts and stops, with a lot of side to side movement just to cover more ground. Their general appearance is best described as stocky and compact, with short legs and very hairy bodies. Their colors range from the nearly all black species mentioned above, to some with bright red abdomens, combinations of red, yellow, tan or other shades of color. I once found a wingless wasp called a Velvet Ant, whose female is quite capable of inflicting a painful sting, with color patterns on her back strongly resembling those of a jumping spider. This mimicry might offer yet more protection for her from her own enemies.

Like all true spiders, the jumping spiders do create silk, but not for web making. Instead, they use the silk to line their places of refuge to make them more comfortable, they use the silk to create a covering for their cluster of eggs, and they also commonly string a line of silk behind them as they roam about on walls or patios. It is thought that this line of silk serves as a “drag-line” enabling the spider to stop its fall should it fall or leap off a surface. It then could pull its way back up the line of silk to return to the surface, and avoid falling all the way to the ground below, where various unknown dangers could be lurking.

We face many possible dangers in a natural environment, but spiders do not deserve the level of fear that we give them. Certainly many kinds are capable of biting us, and some of these could, potentially, cause us a health problem, but most kinds should be enjoyed for the interesting lives they live. The most dangerous spider in North America remains the Black Widow species, whose venom affects our nervous system. Nearly all the rest of them are beneficial animals that feed on other small arthropods around our homes, and serve us well in that capacity.