Ecology

Spinders

Anne Gageby
Strawberry Hill Nature Preserve

(5/2024) I have a confession: I’m terrified of spiders. Yes, I’m an environmental educator and yes, I spend the bulk of my time outdoors so it doesn’t make sense. I’m around spiders all the time, especially now that it’s spring. I can’t walk outside without seeing one every few feet. And I can’t even tell you why I’m so afraid of them. There’s just something about the crawlies that edges a little close to nightmarish.

I’ve spent years working on this fear because spiders are so important to our world. The insect population would be unbearable without spiders. And they in turn are food for larger predators. The world needs spiders. So why can’t I love them?

There are some spiders I can be around without having a nervous breakdown. Cellar spiders are mostly fine and some jumping spiders are almost cute in photographs. And Mickie, Strawberry Hill’s resident tarantula, is pretty cool to look at in her enclosure. So maybe it isn’t that I’m completely terrified of spiders but I definitely don’t want them on me. To be fair, I’ve walked through innumerable spider webs in my life and it never gets any easier. And it’s certainly never fun.

I recently taught a Watersheds and Wetlands program to sixth graders and a highlight of one of our stations was seeing a fishing spider moving across Middle Creek and coming to rest on a stick near us. I picked up the stick to show my students and heard more than a few yelps of surprise. The kids were horrified because this spider was rather large – about two inches long including leg span. When we put it back in the creek it moved across the water at a remarkably slow pace, seemingly unbothered by our intrusion into its territory.

Male fishing spiders are about half the size of females, so our spider could have been a male or it may have been a juvenile. I wasn’t going to get close enough to tell. Either way, the kids were morbidly fascinated by the spider and how easily it rested on the stick as we observed it. Fishing spiders aren’t aggressive, nor are they known to bite unless handled improperly. For being a huge spider with an intimidating appearance, they are actually quite tame. Not that I plan on picking one up.

Fishing spiders (dolomedes) are regularly confused with wolf spiders (lycosidae). Both have similar coloring and depending on the species can be a variety of gray, brown, tan, etc. Both are often found inside homes and garages though their woodland habitats are slightly different. Fishing spiders are found in wet areas of woods such as creeks and riverbanks. As their name suggests, fishing spiders are excellent at fishing though their prey are mostly insects. They have excellent eyesight and fine hairs on their legs which detect vibrations in the water much like a web-spinning spider feels vibrations on spider silk. That’s a pretty cool aquatic adaptation and not their only one. Fishing spiders are able to submerge their bodies under the surface of calm water. The hairs on their body trap air bubbles and allow them to breathe while they wait for prey. They’ve been known to stay submerged for an astonishing 30 minutes at a time.

Wolf spiders, on the other hand, are found in drier wooded areas, backyards, gardens, meadows, and homes. They build or take over existing tunnels in the soil, under stones and firewood. Inside a home, they seek shelter under furniture and other protected, covered spaces. They primarily hunt at night though they’re frequently seen during the day. Wolf spiders are generally not aggressive and prefer to run than attack. When cornered or threatened, they will bite though their venom isn’t medically significant unless a person is allergic.

There are roughly 30,000 species of spiders worldwide, 3,000 of which are found in the United States. Pennsylvania is home to around 45 species of spiders. Of these, only two are known to be medically significant: black widows and brown recluses. Black widows are native to our state but brown recluses are not. Generally speaking, brown recluses are not common as they struggle to survive our cold winters unless they find a suitable space to overwinter inside a heated building. They are more frequently found among items shipped in from other states. Still, it’s smart to keep an eye out for both black widows and brown recluses because their bites are problematic at best.

The thought of a spider jumping on me is enough to make me break out in a cold sweat but I have to admit there’s something almost adorable about jumping spiders, at least on a video or in a picture. They’re stocky and colorful, and don’t look menacing the way a black widow does. Jumping spiders belong to the Salticidae family and our area is home to four species: the zebra jumper, emerald jumper, bold jumper, and bronze jumper. Most are quite small, shy, and harmless with a tendency to flee rather than bite.

Jumping spiders are interesting little creatures for a couple of reasons. Some species are known to be tetrachromatic, meaning they can see all the colors in the visible spectrum, and, unlike humans, they can see the ultraviolet portion of the electromagnetic spectrum. And there’s a study going on in Germany that found evidence that jumping spiders might dream. Yes, really! Researchers discovered that jumping spiders rest upside down on silk thread and while in this position the spiders’s legs curl, they twitch, and even show signs of eye movements similar to those in sleeping humans. It’s believed they go into a REM sleep-like state and exhibiting these behaviors is indicative of dreaming. Even the most arachnophobic person has to admit that’s pretty cool. Spiders in general have another fun adaptation: their blue blood. Human blood is red due to iron-containing hemoglobin transporting oxygen through our system. But spiders, along with octopuses, horseshoe crabs, snails, lobsters, and a handful of other creatures, don’t use hemoglobin to transport oxygen. Instead, their blood contains hemocyanin which contains copper instead of iron, resulting in blue-presenting blood. In a world of primarily red-blooded creatures, that’s a fascinating adaptation.

When I take the time to consider the list of things that make spiders unique, I have to admit, they’re pretty interesting. I may not want one crawling up my arm and I may or may not run screaming from one now and then, but they are kind of amazing. At least from a distance.

Anne Gageby is the Environmental Education Manager of the Strawberry Hill Foundation. Strawberry Hill inspires stewardship of our natural world by
connecting the community with educational opportunities.
 Learn more by visiting StrawberryHill.org.