April 8th, 2006
spider eyes
As some of you may have noticed, I take a lot of photos of spiders. I do my best to identify as many as possible, but I’m just a rank amateur when it comes to IDing arachnids. I figure I’m doing okay just to get spiders into the the right families. Beyond that, I do my best, but often don’t get too far. There’s a lot to know and only a few good identification guides. The truth is, it’s not all that necessary for me to know the exact species of a spider in order to enjoy watching and learning more about it — so I try not to get too hung up on the IDing thing.
One thing I have learned after a few years of insect photography is that spiders have very interesting eyes. Most spiders have 8 eyes which vary in size and placement depending on species. So, knowing something about spider eyes can actually help when you’re learning to ID spiders. This morning, I picked out a few examples — from both recent and older photos — to illustrate some of the variations that might be seen by anyone who takes the time to examine a few backyard spiders.
At the top of this post, you’ll see a Jumping Spider (Family Salticidae). Members of this family do not build webs for capturing prey. Instead, they prowl around looking for prey to capture — which is exactly what the spider in the above photo has managed to do. As you can see, this spider has a very large pair of eyes at the center front. Eyes located at the center front are called “anterior median eyes”. When you see a big set of eyes like that, it usually means that you’re looking at a spider that is a hunter — like the jumping spiders — that must have very good eyesight so that they can locate and capture prey. By the way, this spider does have eight eyes — but four of them aren’t too visible. If you look hard, you’ll see the rear-most pair of eyes back on the side of the head region. Those are called “posterior lateral” eyes. There is actually another pair of eyes in between the front and rear pairs of eyes — unfortunately not too visible in this photo, but they are the “posterior median” eyes.
The next spider has a completely different eye arrangement. This spider is a Misumena vatia – often called a Flower Crab Spider. It belongs to the Crab Spider Family (Thomisidae). These spiders don’t move around a lot. Instead, they find a suitable location and then let their prey come to them. They often sit in the center of an attractive flower, looking upwards, legs raised skyward, waiting for an unwary bee, hover fly, or other victim to come looking for pollen or nectar. I have often seen one of these spiders sit motionless for hours as they wait for their prey. I’ve also found the odd dead bee inside of a flower blossom, and when I’ve investigated, found a spider hanging onto it down inside the bloom. As you can see, this spider’s eyes are all contained within a very small area facing front and center. No doubt, they suit this spider’s hunting style, which is to concentrate full attention on an object which comes directly into the spider’s grasp. By the way, here’s a photo of the whole spider just to give a better idea of how it looks when it’s waiting for prey to come within its grasp. I might add that, despite this fairly sedentary hunting technique, these spiders seem to be incredibly successful — which probably says something for patience and perseverance.
The next spider is some species of Orbweaver (Family Araneidae). I think it’s probably a Marbled Orbweaver (Araneus marmoreus), but I always find the various species of Araneus a bit difficult to sort out. In any case, this spider spins a large, circular web which can be 20 inches or more in diameter. It then sits in a safe spot, either on the web or nearby. I usually find them sheltered under the bent tip of a Timothy grass seedhead, just to top and side of their orb. They are said to have poor eyesight — which isn’t too surprising considering the minute size of their eyes. These spiders depend on feeling vibrations from struggling insects in their webs rather than on seeing their prey. When they feel vibrations and tugging on strands of their webs, they crawl to that spot to kill and wrap their prey.
I’ve included these last two spiders as examples of hunting spiders with interesting eye arrangements. I’m quite sure that the above spider is a Dark Fishing Spider (Dolomedes tenebrosus), and is a member of the Nursery Web Spiders (Family Pisauridae). As North American spiders go, this is one of the larger species. As can be seen, the 4 anterior eyes are fairly small and lined up in a row at the front. The center rear pair (posterior median) of eyes are quite large, with a small pair of rear side (posterior lateral) eyes a little off to the sides. This spider hunts in or near water and has good vision which makes it able to capture prey such as large insects, and aquatic creatures such as tadpoles and small minnows.
The last spider of the group is this handsome unidentified Wolf Spider which I photographed last weekend (April 2). To see a full view of it, click here. Although it’s difficult to see all of the eyes, what I would point out is that Wolf Spiders (Family Lycosidae) have a pair of fairly good-sized posterior median eyes (center rear eyes), and also a somewhat conspicuous pair of lateral posterior eyes (the rear set on the sides of the cephalothorax). Both Pisauridae and Lycosidae spiders have a reflective layer of cells at the back of the eye (tapetum) which give them good night vision.
Well, hopefully my explanations weren’t too confusing and I didn’t make any particularly grave errors (feel free to post a comment if you spot an error). There’s a lot more to the topic of spider eyes and vision, but I’ll have to leave some of that for another day. Got to get out hiking as it’s a very nice day here in eastern Ontario!
Btw, for those who are interested in such things – I’m sometimes asked about favourite field guides, etc.. For spiders, a good, basic guide that would get someone started with spiders is “Spiders of the North Woods” by Larry Weber (Kollath-Stensaas Publishing, 2003). Sorry I haven’t put up a link as I’m in such a hurry to get out of here. One of these days, maybe I’ll get around to putting up a fancy page of favourite books… but don’t hold your breath. (-:
Tags: spider eyes, spider vision, Jumping Spider, Salticidae, Crab Spider Family, Thomisidae, Misumena vatia, Orbweaver, Araneidae, Araneus marmoreus, Dark Fishing Spider, Dolomedes tenebrosus, Pisauridae, Wolf Spider, Lycosidae
April 8th, 2006 at 6:10 pm
Wonderful spider photos! The first spider actually looks cute (in a fuzzy, big-eyed way), and I hate spiders!
April 9th, 2006 at 9:16 am
“I might add that, despite this fairly sedentary hunting technique, these spiders seem to be incredibly successful — which probably says something for patience and perseverance.”
There is another reason why crab spiders are so good at catching bees – they can tell which flowers bees prefer from their smell so lie in wait in the best blooms. See: Floral quality signals lure pollinators and their predators http://www.sekj.org/PDF/anz41-free/anz41-421.pdf
Love the pics BTW
April 9th, 2006 at 1:32 pm
Lukas and Beth — thanks for the feedback on the photos.
And Lukas — thanks for the link to the paper on floral quality, pollinators and predators. I’m also very interested in Phymata (Ambush bugs), and based on observation, I believe they are very much in tune with best floral quality. An odd aside to the crab spiders and flowers, last summer, I photographed an extremely large Misumena vatia that spent several days hiding among the top leaves of a young Red Oak tree on my front lawn. It sat posed in the typical hunting mode, but I never saw it make a successful capture. I remain somewhat puzzled as to why it would have decided to stake out a spot on the top of a small tree instead of on any of the nearby flowers — especially as it was so large and must have been quite successful at capturing prey in the past.
April 10th, 2006 at 11:14 pm
Very interesting and helpful post Bev. I think you’ve given me a clue to the identity of a tiny spider I photographed a while ago: some kind of jumping spider, at least going by the arrangement of the eyes. And given that I found the spider prowling around, as befits a non-weaver.
(http://thomasburg-walks.blogspot.com/2005/11/infesting-ark.html)
April 10th, 2006 at 11:45 pm
Pamela — I just visited your blog to take a look at the spider and posted a comment there. It’s definitely a Jumping Spider (Salticidae), and may well be a Zebra Jumper (Salticus scenicus) or similar. The large pair of anterior median eyes are very typical of almost all species of Jumping Spiders.
April 11th, 2006 at 9:57 am
Having been out of the country for 3 weeks, I have been struggling to catch up with my favourite blogs. Amazing how much information and what beautiful photos can arrive in three weeks. I’ve not given your entries all the time they need but I need to stop and tell you how much I am enjoying your blogs. My partner, Églantine, and I spent many hours in our meadows last season looking for and photographing insects, spiders, flowers, etc. but we have a long way to go to even get close to your observations, notes, and photos. You are a real inspiration! Thanks!!!
April 12th, 2006 at 3:24 am
O.W. — It’s always wonderful to hear of others who spend time observing and photographing insects and spiders. Thanks very much for your kind comments!
May 10th, 2006 at 3:21 am
Love your ‘site. Have anything on mystical creaters like dragons? I’m just crasy ’bout dragons!!!!!
May 10th, 2006 at 1:55 pm
Jean – nope, not yet. Perhaps there will be a few snapdragons later this summer.
October 23rd, 2006 at 2:08 am
wow,I like the one who cross in the purple flower.
October 26th, 2006 at 6:28 pm
i think spiders are cool. i am not afraid of them but i do have a healthy respect for them. i want to learn more on the black widow.
October 27th, 2006 at 11:38 am
hi, great pictures. i am looking for a picture of a (common to me) brown spider with two stripes on its bum. i see them all around my yard and house eek! i live in utah. do you have any idea what it would be?
October 27th, 2006 at 3:16 pm
tido – thanks! that’s one of my favourites too.
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amelia – I’ll be posting a piece about a Black Widow spider sometime soon. We don’t have them up here in Ontario, but I photographed one while in Oregon a few weeks ago.
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linda – It’s difficult to say what that spider might be from the description and due to your location — I’m up in Ontario, Canada, so my knowledge of spiders tends more toward those species found up here. If the spiders are commonly seen around your yard and often found on the ground, they are probably either some species of Wolf Spider (Lycosidae), or Ground Spider (Gnaphosidie). If they are in webs in bushes, there are a lot more possibilities. In web builders, the shape of the web can tell you quite a bit about the type of spider.
October 28th, 2006 at 8:33 pm
They are great pictures, But I am deathly scared of spiders, I though that I was going to faint when I opened this website!
November 2nd, 2006 at 4:25 am
They are great pictures, But I am deathly scared of spiders, I though that I was going to faint when I opened this website! Did you take the pictures yourself?
November 2nd, 2006 at 4:28 am
Hi Melissa – Yes, I took all of the spider photos myself – as is the case with just about all of the photo on my blog.
November 11th, 2006 at 6:36 am
i luv da photos, so exotic, i put one as my desktop image
November 21st, 2006 at 8:45 pm
Hi – wow, amazing photos! They’re all so good quality and Oh! so clear! wow…
November 27th, 2006 at 2:26 pm
Thanks for some photos! They’re so amazing!!!
I don’t very like spider but the photos are so great!!!!!
Thanks again!!
December 17th, 2006 at 1:22 pm
Very nice pictures. Since I am interested in eyes anyway, I will check back to see if you find anymore interesting critters.
December 19th, 2006 at 3:53 am
Burning Silo,
Possible hint about your flower spider in tree. Recently, the red “chevrons” have been identified as “bee guide” mimicry. So when a bee seems them in the UV spectrum, it responds as it does to the true bee guides that center many flowers and point the bee toward both nectar and pollen. The flower spiders are imitating ultraviolet-visible patterns that flowers evolved so that bees would help them make seeds–an excellent co-evolution.
Also explains why/how the bee does not see that huge white spider lurking there.
Great macros!
December 19th, 2006 at 1:03 pm
John – thanks! Very interesting about the red pattern on the flower spiders!
January 22nd, 2007 at 2:05 pm
[…] Regarding the wavy pink markings on the abdomen, back in April, when I wrote a post about spider eyes, John Caddy of the Morning Earth website left an interesting comment that I haven’t done any follow-up on, but that makes sense: Possible hint about your flower spider in tree. Recently, the red “chevrons” have been identified as “bee guide” mimicry. So when a bee seems them in the UV spectrum, it responds as it does to the true bee guides that center many flowers and point the bee toward both nectar and pollen. The flower spiders are imitating ultraviolet-visible patterns that flowers evolved so that bees would help them make seeds–an excellent co-evolution. Also explains why/how the bee does not see that huge white spider lurking there. […]
January 25th, 2007 at 11:31 am
Thanks for the delightful pictures the info about eyes is exactly what I was looking for.
January 25th, 2007 at 4:15 pm
Richard – Thanks! Glad you found what you were searcing for.
February 6th, 2007 at 7:02 pm
Wow, these pictures are amazing. I love taking photos, especially of bugs. I wish I had a telephoto lens! I’d imagine that’s how you seemingly got so close to these spiders…I’d never get that close to anything with my camera or otherwise. I absolutely hate spiders and insects…they creep me out. However, when you get up close and personal to them in photos, they’re more cool than creepy! I just don’t like the idea of an actual bug being close to me. So photos are okay! I never knew there were this many species of spiders in one place, especially in Canada. Such a good job with this website too :) Loved your site and photos!
February 6th, 2007 at 9:30 pm
Jaime – Thanks. I use a macro lens and just shoot from very close to the spiders. I’m not nervous of being around spiders or insects, so that makes it eashy. Yes, there are lots of species of spiders in Canada. And yes, you’re right… when you get a chance to see the spiders in photos, you find out that they are quite interesting and not actually scary at all.
February 7th, 2007 at 12:13 am
I love spiders. I never chase one out of my place as they are welcomed guests any time. I provide for them droplets of water and try to let them roam around freely.
For those of you who are into insect and spider photography, just a piece of advice. Place your subjects in a jar in the fridge for a little while. They’ll get slow and easy to place in a chosen context and to photograph.
February 15th, 2007 at 8:48 pm
hi i hav a hobo spider 3 tarantulars and 1 sathis spider
February 17th, 2007 at 12:10 am
Hi amy – It sounds like you have quite the collection! (-:
February 24th, 2007 at 2:10 am
wow thats creepie but cool!!!
March 2nd, 2007 at 6:13 pm
it is a very informative page… i want to give a comment a bout spiders .. all spiders has spinnerets and aproximately 50% of them use it to spin a web to trap its prey but the other half don’t use it in feeding so it may depend on hunting like hunting spiders which you mentioned.
March 28th, 2007 at 10:33 am
gross. :P
June 27th, 2007 at 12:52 am
One of my sisters just phoned to ask my other sister and I, did spiders have eight eyes, or two eyes? After finding a rather spectacular to her, specimen in her backyard perched upon it’s web, when she was doing yardwork, earlier in the day. Googling the question brought me to this creepy but informative site for the information. Great photos by the way, creepy or not…
June 27th, 2007 at 5:18 am
Sabrina – Thanks! Glad that you found the information on my website useful!