Sunday, July 24, 2011

The itsy bitsy spider(s)....

NOTE: If you are squeamish about spiders, approach this post with caution. I encourage folks to face their fears head-on, and I firmly believe that knowledge and exposure can help to assuage fears about things such as spiders and snakes, but I am also sensitive to the fact that some people may run for the door if they see a picture of a spider. So, all I ask is that you try. Let's begin!

While birds have occupied a large portion of my mental resources this spring and summer, other creatures have been catching my attention as well. I've spent time in past years photographing moths, butterflies, robber flies, wasps and other insects, but this year I've been trying to photograph more spiders. Though much maligned, disdained, and feared, spiders are fascinating creatures. But aren't they poisonous and dangerous?

All spider species in Ohio possess venom, a necessary substance for paralyzing their prey. But keep in mind that spiders eat insects (and other spiders), so the tiny amount of venom that they might inject into a human, which is many, MANY times larger than their intended prey, coupled with human physiology (which is obviously much different from that of an insect), will protect us from 99% of spider bites. In Ohio, the only spider species whose bite would warrant a trip to the ER are the recluses (Brown and Mediterranean) and the Black Widow, all 3 of which are relatively rare in the state. Common sense (don't stick your hand into an area where you can't see what's inside) and shaking out of any loose clothing on the floor (including gloves and shoes) should keep you safe from harm.

Now - if that didn't scare you off and you're still with me, let's take a look at some of the spiders that I've found around our property. Let me note that I welcome any corrections to my identifications. I'm still learning when it comes to spiders, and as is the case with my first exposure to new taxonomies (classifications) and field guides, things tend to all look the same until I've spent enough time with the creatures to get a grasp of the things that set them all apart from each other.

Some facts to consider when trying to identify spiders include, type of web (or lack thereof), habitat, body shape, and seasonality (time of year when they are active). With spiders, the females are typically larger than the males, and often times more showy, and it will almost always be females that are on the webs.

Here is an orchard spider (Leucauge venusta). Not sure why, exactly, they are called orchard spiders, since they prefer to dwell in forests, but the clincher for the ID on this one was its web. My field guide* says that the web is "typically at an oblique angle, nearly horizontal." I don't have a diagnostic picture of the web, unfortunately, but I'll ask you to take me at my word when I say it was nearly horizontal. They build an orb type web, which is the kind you might typically think of when you think "spider web" - a basically round shape with parallel lines within, à la Charlotte's Web.

The coloration is fascinating and beautiful. Pretty colors are one thing that some of these spiders have going for them, and help me to have a better appreciation for them.

This view from the back shows an amazing silver color, with some nice black markings to boot. It's quite a piece of art, if you ask me!

Next up we have another forest dweller, although it can also be found in fields. It builds a funnel type web, the shape of which is pretty self-explanatory. This is a photo of its web. I love how it incorporated the fallen beech leaf into the web, using it as a kind of template, if you will, for the funnel itself.

This spider was hard to photograph because it was very wary of any movement near the web. This is a blown-up shot of the spider down within the funnel. The more I look at this, the more it seems like there are actually two spiders in this funnel. Needless to say, there's no real way to ID the spider from this vantage point.

Due to its skittish nature, I had to walk away from this web and come back a little later to try again. Unfortunately I was never able to get a face shot, but we can see an interesting detail at the back end of this spider. You may notice something pointy at the very back of the abdomen. Those are spinnerets (the finger-like silk spinning organs), and their placement is very telling for this type of spider, which is grass spider of some sort. There are apparently 5 different species of grass spiders in Ohio, but I do not know which one this is.

Grass spider, Agelenopsis sp., with closer view of spinnerets at rear of abdomen.

Speaking of spinnerets, here's a photo of said piece of anatomy in action. I have no ID for the spider, but I was pretty lucky to get some shots of it wrapping up this morsel of food in silk to be kept for a future meal. All spiders possess the ability to spin silk, but not all spiders make webs. Most wolf spider species, for example, do not make webs. Silk can be used for storing eggs (cocoon or egg sac), and some species of spiders will use silk for a process called "ballooning" or "kiting," which allows them to carried through the air by wind currents (I recall watching spiders ballooning in the field last fall - it was quite an amazing sight.) So silk production is definitely another cool thing spiders have going for them (in case I'm losing you to the "ick" factor!).

I mentioned that body shape can be helpful in identification, and that couldn't be more true in the case of this spider. Even from the silhouette shown on this leaf, one might be able to guess the spider. The shape of the abdomen is reminiscent of the shape of an arrow, so it is aptly named arrowshaped micrathena (Micrathena sagittata).

Here is the arrowshaped micrathena on its web (we can see it's an orb weaver by the shape of the web), hanging with its back to the ground, giving us a ventral view.

Her web happened to be hanging horizontally, and was very close to the leaves of this False Solomon's Seal, so it was difficult for me to get underneath to get a photo of her diagnostic yellow abdomen. But hopefully you get the idea. These are spiders that build webs in the understory, and are fond of moist woods.

Here's another spider in the Micrathena genus, and this is one you'd likely come eye-to-eye with when walking along a trail. The spined micrathena (Micrathena gracilis) is notorious for building its web across trails. While the spikes are certainly menacing in appearance, they would be of no harm to you.

I would have to think that that huge, spiny abdomen would be heavy and cause for some balance issues, but it's obviously evolved to be this shape for a reason.

Looking up from below, we can see all 5 sets of "spines" that are on the abdomen. Interestingly, as I write this and and compare my photos to other photos of this species of spider, I am drawn to how very round her abdomen is, which is not the typical shape for this spider. This leads me to conclude that this spider is gravid (swollen with eggs).

I spent a long time photographing this spider from many different angles, and I'm glad I was able to do so. I'm not sure I could have fully appreciated all of these interesting markings without the ability to enlarge the photos. And yeah, this lady is definitely pregnant.

One last look at this orb weaver on its web. The field guide says that the small (narrow) spaces between the threads indicate that this spider's typical prey is pretty small.

Finally, we come to the pièce de résistance, the last spider for this show-and-tell series. I'm taking a moment to prepare you because it might freak some of you out. There is no need to be alarmed. But it is a black widow.

This is not the first, nor will it be the last, black widow we have found on this property. Dave found this spider at the door to our garage, so she had to be moved in order to avoid an encounter where she might feel threatened.

I'm not quite sure what she was doing out and about with her egg sac. This door gets opened most days of the week, so it's not like she had had a lot of time to establish a web there. Regardless, Dave used a very long stick to remove her (and her egg sac) from the door. She chose to stay on the stick after it was laid down.

Some of you may be wondering where the characteristic hourglass marking is. The hourglass is only on the underside of the abdomen. I surely did not want to move her just to see that marking.

At no point did she show any signs of aggression. She stayed with the egg sac for a while, but I'm pretty sure that the sac had been abandoned by the time I checked it the next day, which I thought was odd. I'm not sure if the eggs ever matured. The sac is still on the stick, although it seems to be a bit flaccid at this point. These photos were taken about a month ago, but widow spiderlings typically hatch within 8-10 days of being laid. I have never observed spiders hatching from their egg sac, so I don't know what kind of state it would be in if they survived and hatched out.

This is just a small survey of countless thousands of spiders that surely live near my home, and yours, too. Spiders are important predators that help control pests in our landscape. If they were not around, we would surely notice other insect populations spiraling out of control. If you find one in your house and can't deal with it being there, at least attempt to escort it outside, rather than just killing it.

* The field guide that I consulted for the majority of the information presented here is the Common Spiders of Ohio Field Guide, published by the Ohio Division of Wildlife, Department of Natural Resources. It is Publication 140. Visit for more information and to request your own (free!) copy. Funding for this field guide and others (covering a wide variety of Ohio wildlife such as common birds, owls, butterflies, amphibians, mammals, reptiles, sportfish and more) comes from donations to the state income tax checkoff program, sales of the Ohio wildlife legacy stamp, and sales of the wildlife conservation license plate (the Cardinal license plate).


rebecca said...

Gorgeous photos, especially the one of the spinneret in action.

Jain said...

Great shots! I’ve never seen a Black Widow, up close or otherwise. She looks so protective of that egg sac – I hope the kids are alright (and well away from your door). Though I’m a fan of spiders, I guess I’m not going out of my way to find one of these.

Loved the spinneret shot, too.

Micrathenas are fun. It seems as if someone asks me what they are at least once a year, and I look like ~such~ a know-it-all (which I’m definitely ~not~!) when I rattle off the name.

I have two favorite spider books that I wonder if you’ve read: The Spider by John Crompton is a rollicking good read, and The Biology of Spiders by Rainer Foelix is text-bookish and loaded with great info.

Judy said...

Lovely post! I did not realize there are so many types of spiders! Now, do you have an explanation for why there are five times as many spiders in my daughter's room than in the rest of the house?

Heather said...

Rebecca - Thanks!

Jain - I've never gone out of my way to find a widow, either - they always present themselves to us! I have not heard of the books you mention, but I will add them to my always-growing list of books to check out - thanks!

Judy - Hmmm... is your daughter trying to stage her own version of Charlotte's Web in her room? ;)