Monday, February 2, 2015

Spiders, Spiders, and More Spiders

So it's been awhile since I've lasted posted, more than a month actually. I've found myself in sort of a writing rut, and school has been a busy whirlwind of things to do so far this semester. I haven't been able to get to writing like I've wanted too. Excuses aside, I'm back.

Jumping Spider eating fly
A jumping spider (possibly Paraphidippus aurantius) chows down on a fly.
So here I am, writing a new post. This one is about a group of much feared, much hated, much maligned animals. Spiders. Why dislike spiders? I think most of that is societal. Most children are taught to dislike and fear spiders. "They're dangerous," or "They're scary." They keep that mindset as they grow up and end up passing that mindset onto their own children, perpetuating the completely-unnecessary and inane spider hate we have in our culture.

Are spiders really dangerous? A few species are dangerous. But dogs are dangerous, and horses, and most other pets. Yet people love dogs, horses, cats, and the like. We acknowledge those animals can hurt us, but we respect them in such a way that we minimize the risk of getting hurt. This is exactly how we should treat dangerous spiders, or any animal really. You don't go up and hit a stranger's dog, or any dog; that is asking to be bit. No one blames a dog that bites a person when it feels like its well-being is threatened and it must defend itself; and just like the dog, we should not hate spiders simply because we might force an individual into a predicament where that individual fears for its well-being and bites us. That is our fault, not the spider's.

Wolf Spider Schizocosa
A large, but completely harmless, wolf spider of the genus Schizocosa.
Almost all spiders are venomous, but that venom is almost always too weak to hurt a human. There are a few species of spiders with venom that can harm a human. In Ohio, we have up to three species of truly dangerous spiders. The first two are black widows, specifically the Southern Black Widow (Latrodectus mactans, photos here) and the Northern Black Widow (L. variolus, photos here). Both species are highly uncommon, but can be found throughout Ohio. They are shy, rarely encountered spiders (I've only seen one, and I've been looking for them), and a bite from them, while painful and often requiring medical attention, will almost never end in death for a healthy adult.

The last dangerous spider species is the Brown Recluse (Loxosceles reclusa, photos here), depending on who you talk to and what range maps you look at. It is unsure if we have native Brown Recluses in Ohio; ODNR says there have been no verified specimens from outdoors, but that doesn't necessarily mean they aren't there. The very few that have been recorded in Ohio have been found indoors, most likely brought in by humans from elsewhere in their range, as they like to catch rides on furniture and the likes. Regardless, Brown Recluses in Ohio are very, very rare and highly restricted to the area around Cincinnati. It is important to add a note about their bite. Brown Recluses get a bad rep for their bite, which supposedly causes necrosis around the bite area. If you're seen photos of supposed bites, you know what I'm talking about. However, studies have found that only about 37% of Brown Recluse bites actually result in necrosis (the death of tissues). On top of that, studies have also estimated that nearly 80% of all "Brown Recluse bites" have actually been misdiagnoses. Most of the time it's actually MRSA, but can also be a host of other infections. The point is, Brown Recluse bites are incredibly rare due to their shyness, and even when they do bite it will most likely be harmless. If you ever see a supposed photo of a "Brown Recluse" bite, always be wary; it's more than likely something else. Another important thing to add is that doctors are not entomologists. Unless you watch a spider biting you, you can never be sure a wound was caused by a spider. On top of that, a doctor can never positively identify a spider species from a possible bite unless they have the actual spider.

Spiders do bite, there is no denying that. And in Ohio, unless they're one of the three listed here, you will be fine. Many spiders rarely bite, and it takes a lot to make them want to bite you. You have a better chance of being stung by a bee than bit by a spider. Most spiders bite when a human accidentally begins crushing one, like if you're putting on a shoe with a spider in it, or with other cases of making the spider feel in danger. Regardless, treat all spiders with respect and obviously be aware if the spider starts acting defensively, in which case they are probably to the point of biting.

Dark Fishing Spider dolomedes tenebrosus
The spider above is one that many people completely freak out about when they see one. Meet the Dark Fishing Spider, Dolomedes tenebrosus. Dark-Fishing Spiders are some of the largest spiders in Ohio, reaching up to a total size of 4 inches across (basically the size of your palm). While massive, these guys are totally harmless. They are really shy and will many times run away upon seeing a human. Occasionally they will wander into buildings and homes, often resulting in terror-stricken inhabitants. There's no need to worry; simply try and carefully put it in a plastic container in order to release it outside! Dark Fishing Spiders are forest spiders. They do not build a web, and instead actively hunt down prey. Look for them low on tree trunks at night, or near rocky areas with water (which is where I find most of mine).

Six-Spotted Fishing Spider, Dolomedes triton
Next up we have another fishing spider, the Six-Spotted Fishing Spider, Dolomedes triton. Spiders in the genus Dolomedes are known as Fishing Spiders as most of them are at least semi-aquatic. The previous Dark Fishing Spider is not always that aquatic and can be found very far from water. The Six-Spotted Fishing Spider, on the other hand, is the most aquatic fishing spider in Ohio. These guys are really cool. This species can actually walk on water, as shown above. They will often wait on the surface of water for prey to come by, or actively hunt prey down. Water Striders are a favorite, as are terrestrial insects that fall helplessly into water, but the Six-Spotted Fishing Spider will also hunt prey in the water. They are capable of diving up to 7 inches under the water to catch aquatic invertebrates, tadpoles, and even small fish! Pretty awesome, eh?

White-Banded Crab Spider, Misumenoides formosipes
This tiny spider sitting on a flower is a White-Banded Crab Spider, Misumenoides formosipes. It's small, but note the characteristic white-band that runs across the face underneath the eyes. If you want a larger version of the photo, just click on it! This species, as the name suggests, is a species of crab spider, family Thomisidae. The crab spiders are so-named for their crab-like appearance. Most, but not all, crab spiders in the family Thomisidae are sit-and-wait ambush predators, as the White-Banded Crab Spider is. Basically, they sit on a plant like the one above and wait for an unlucky pollinator to come by. If the pollinator is the right size, the spider will lunge and grab it for a meal. The individual above is a male White-Banded Crab Spider. The males of this species have a golden abdomen with their four front legs being dark brown/black. The females of this species can range from gold to white. Interestingly, the females can actually change color to match the flower they are sitting on. For example, if a female picks a white flower to hunt from, she will become white, and if it's a yellow flower, she will become yellow. The males, like the one above, are locked in with their colors, however. Most of the time people are taught that the females change color in order to be camouflaged so they can be undetected by potential prey until it's too late. A relatively recent study (Brechb├╝hl et all, 2006) has found that this is not the case; color-matching individuals had the same success rate as mismatched-colored individuals. The actual meaning behind changing colors is still up for debate, but it most likely isn't for better hunting success.

Pisaurina mira
And last we have one of my favorites, Pisaurina mira, also known as the Nursery Web Spider. This species loves to hang out on the edges of forests, especially when there's bushes, tall grass, and other similar herbaceous plants. I always find many at A.W. Marion State Park in Pickaway County where a medium sized marsh/grassland area transitions into an established forest. These are large spiders, with some individuals I've seen approaching 2.5 inches wide (that is including the legs). They come in a range of colors, from very light yellow-brown to a dark brown. The markings are somewhat variable as well; BugGuide has a nice layout of the different variations, which you can see here. Why are these known as the Nursery Web Spider? Like the others I went over in this post, this species does not build a web to capture prey; instead it actively hunts down prey. The females of this species (and the others in the family Pisauridae) will, however, carry around an egg sac (photo here). Upon the spiderlings nearing hatching, the female will construct a "nursery" made out of web and place the egg sac inside. After the spiderlings hatch, the female will defend this nursery in order to keep her hundreds of offspring alive.

So I ended up writing a lot more than I thought I would, but I just love spiders. I love how misunderstood they are, and they're just so amazing once you can get past the whole "ew a spider" issue so many people have. If you don't like spiders, I strongly urge you to give them a chance!