Friday 5 (on Saturday): A Web of Spiders

One of the great things about working at a field station run by a natural history museum is that you’re surrounded by people who share your interests.  This is no small thing when you’re an entomologist!  Sure, we get along famously with other entomologists, but once we leave the comfort of our own kind, we’re exposed to a lot of squeamishness and people who really don’t get  how we could possibly be interested in insects for any purpose other than figuring out how to kill them as quickly as possible.  It’s GREAT to be around other people who appreciate nature when you love nature, and it’s part of the reason why I love my job.

Case in point: yesterday morning, a museum retiree stopped by our lovely construction trailer/office to chat for a few minutes.  He’s a great guy and incredibly knowledgeable, so we discussed a few of the trees in the arboretum he’s built in the lowland area of the field station over the last few years and a few other things before he headed out.  He wasn’t gone long though!  He came back in about 20 seconds later saying, “You all have GOT to come see this!!” and rushed back out the door.  I was thinking he’d seen the sort of thing that most people at Prairie Ridge get excited about, a large bird, snake, or mammal, but instead he’d found a stick mantid egg case on the underside of the handrail for the stairs to the other entrance to the trailer.  Woo!  Stick mantids are cool, so I was excited.  We had admired the egg case for a few moments when the arborist looked up and pointed at this with a big grin on his face:

scarab in spider web

Scarab in spider web

A scarab beetle was dangling from a large spider web!  Clearly it had gotten tangled in the web and had been trapped.  But neither the web nor the beetle were what excited our arborist.  It was this little dew drop spider:

Dew Drop spider

Dew drop spider

That spider was about 1/4 inch long and was EATING THE BEETLE!  The arborist was practically bouncing up and down as he watched the little spider eating the beetle.  These spiders are cleptoparasites, animals that steal food that other animals have captured.  In this case, our little spider was feeding on a large beetle that had been trapped in the web of a much larger orb weaver spider.  The orb weaver was hidden inside the handrail or the day, so the little dew drop spider was helping herself to some food.  The arborist started looking at the web, saying that it was likely that a much smaller male was hanging around too.  Sure enough, there he was, a couple of inches away!

male dew drop spider

Male dew drop spider

At this point, we had a complicated food web going, with a small cleptoparasitic dew drop spider stealing food from a larger predatory orb weaver spider that had captured it, all while a male dew drop spider looked on.

That alone would have been pretty cool, but things got more exciting when we startled the little dew drop spider and she dropped onto the stairs below.  She stayed completely still for several minutes as we all watched to see what she would do.  She eventually made her way over to the handrail, her swollen abdomen flopping from side to side.  We were watching her crawl up the handrail support and debating whether she was full of eggs or not when the arborist exclaimed, “Wow!!!  Did you see that??!!”  He pointed at this:

Jumping spider eating dew drop spider

Jumping spider eating dew drop spider

A little jumping spider, likely a juvenile of one of our larger jumper species, had dashed out of the space between two of the handrail supports and snagged the dew drop spider!  So, now we had a predator eating a cleptoparasite who was stealing food from a predator while the male dew drop spider looked on.  Quite the complicated little food web was developed!

We watched for a few minutes as the jumping spider carried the dew drop spider’s limp body before the arborist wandered back to his car and the rest of us headed back inside.  I looked over the photos I’d taken and realized that I hadn’t gotten any decent shots of the male spider, so I went back out to snap a few more shots.  As I walked past the handrail, I looked to see how far the jumping spider had gotten in devouring the dew drop spider.  Right at that moment, another jumping spider entered the mess, attempting to grab the first jumper!  The attacker missed and the jumper with the dew drop spider scurried away.  I followed the second jumper around with my camera for a few minutes, and it eventually crammed itself down into a little gap between the handrail and the support and looked out at me:

jumper in gap

Jumper in gap

If the second jumper had succeeded, it’s hard to say how the food web would have been impacted.  If it had eaten the other jumper, that would have been a predator eating a predator that was eating a cleptoparasite that was stealing food from another predator while the male dew drop spider looked on.  If, however, the second jumper had snatched the dew drop spider away from the first jumper, it would have been a cleptoparasite eating food captured by a predator who had caught a cleptoparasite that was eating food captured by a predator as the male drop spider looked on!  Regardless, there were 5 different players in this little drama, and that was on a single spider web on a single handrail on an ugly construction trailer where my office is located.

This all illustrates a point: nature is complex if you take the time to look.  If you have a few people who are willing to watch a crazy complicated little spider-focused food web develop with you, well… That makes the experience even better!  I consider myself lucky to work with people who will gladly spend 15 minutes watching little spiders on a handrail.  Here’s to many more similar adventures in the future!

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth
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Well-Nigh Wordless Wednesday: A Little More Saltie

Because you can never have too many photos of jumping spiders in your life:

Jumping spider

Jumping spider

That is all.

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

Friday 5: Why Jumping Spiders Will Always Be My Favorite Spiders

I haven’t always been the biggest fan of spiders, but there’s one group that I’ve loved for as long as I can remember: the jumping spiders in the Salticidae family.  These charismatic spiders, sometimes called “salties” by their enthusiasts, are intelligent, expressive, interactive, and downright adorable compared to most spiders. But don’t take my word for it!  Today’s Friday 5 is all about convincing you all that salties are the best.

Reason Number One: The Eyes

Check  out the eyes on this little saltie, compliments of the magnificent Thomas Shahan:

Saltie eyes

Close up of the eyes of an adult female Paraphidippus aurantius. Photo by Thomas Shahan, used under Creative Commons. Original image available at http://www.flickr.com/photos/opoterser/4228767271/in/photostream/

Salties have very large eyes and are incredibly visual little spiders.   Their eyes are part of what give them their personalities as they are quite capable of and willing to follow you with their eyes – they can really watch you in a way most other spiders cannot.  (They’ll also interact with their reflections in camera lenses, which results in some of the really great head on shots of salties that you see around the web and among Shahan’s work.)  I think their ability to watch you and interact with you makes them seem a little less alien than many spiders – and much more palatable to more people.

Reason Number Two: The Hairdos!

Some salties have wild hairdos.  They can have little mohawks, beards, mustaches, spiky hair…  I think the hair makes these guys absolutely adorable!  I mean, how can anyone be scared of an animal, even a spider, with such ridiculous looking bedhead?:

Saltie hair

Hairdo of the female jumping spider Phidippus mystaceus. Photo by Thomas Shahan, used under Creative Commons. Original image available at http://www.flickr.com/photos/opoterser/6253069072/in/photostream

Fabulous!

Reason Number Three: Saltie Mating Dances

If you’ve never seen one of the saltie mating dances, you’re in for a treat today!  Researcher Jürgen Otto works with Australian peacock spiders and has captured some hilarious footage of their mating dances, including this:

SO funny!  I’ve watched this several times already and it makes me laugh every time.  Nature is so bizarre.  And awesome.  Completely awesome.

Reason Number Four: Peacock Jumping
Spiders Rock.  Enough Said.

The peacock spider in the previous video was pretty impressive, but they don’t hold a candle to this amazing, brilliantly colored beast, also recorded by Jürgen Otto:

Isn’t it great to live in a world where such crazy looking animals exist?  Peacock spiders alone would make me think that salties are the best spiders, even without  all the other crazy things they’ve got going on.  They’re just that cool.

Reason Number 5: They Are Amazing

I saw a TED talk a few weeks ago by Mark Berman about appreciating insects and their relatives.  I really enjoyed it, especially as promoting insect awareness and a greater love for insects is one of my personal goals.  It’s a bit longer and more academic than the other videos I’ve included here, but it’s well worth watching.  And why is it in my saltie Friday 5 post?  Because Berman uses salties as an example of an amazing arthropod – and has more hilarious video footage of saltie mating rituals to share:

I really love the quote at the end:

“The more moments in time you take to look again, the more amazed you’ll be by the world we live in.  But I suggest you shouldn’t be surprised.  You should come to get used to amazing things in your world.”

Couldn’t have said it better myself!  Love the salties and be amazed by them – but never be surprised by any of their fantastic and wonderful traits.

Go salties!

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

Overcoming My Childhood Fear of Spiders

Banded argiope, Argiope trifasciata

Banded argiope, Argiope trifasciata

When I was a kid, I was scared of spiders.  As great as my parents were about letting their kids explore the world and letting us develop our own opinions about the organisms we encountered, I think my fear of spiders was largely my dad’s fault.  He still tells me stories about how our house would have been “overrun with black widows – overrun!!” if he hadn’t hauled a can of Raid out into the backyard and sprayed the heck out of every black widow he found once a week.  He talked about the sun spider (not a true spider, but still an arachnid) in the laundry closet with a hint of fear and has told me the story of my first encounter with a spider several times.  It goes like this.  One night, I called out to my dad, telling him that there was a spider in my crib.  He looked around and didn’t see anything, so he told me I was dreaming and should go back to sleep.  A few minutes later, I called out again, saying that there was a spider in my bed.  He looked again and still didn’t see anything.  I kept insisting there was a spider, so he eventually started pulling off blankets to prove that there was no spider.  Of course there was a spider, THE BIGGEST BLACK WIDOW OF ALL TIME!  Or at least that’s how my dad tells it.  You’d think this spider was about to devour his beloved firstborn, that I was lucky he was there to save me and vanquish the black widow foe.  He wouldn’t ever admit it, but these sorts of stories have led me to believe that my dad might have a touch of arachnophobia.

Long jawed orb weaver spider

Long jawed orb weaver spider, Tetragnatha sp

When my dad, who is rather fearless and tells stories of brave encounters with rattlesnakes and an angry swarm of yellow jackets, actually showed any sort of fear, it sort of rubbed off on you.  So, I was scared of spiders too.  I remember growing up thinking that most spiders were dangerous, that killing a spider was better than risking being bitten.  I used to be so scared of spiders that I’d have nightmares about them lurking menacingly under my blankets.  I would wake up in a panic and start ripping off the covers to prove to myself that there wasn’t actually a spider in my bed.  I knew there wasn’t a spider in my bed, but then again…  My dad had told me that story about the black widow in my crib, so maybe my subconscious mind was trying to tell me something…

Crab spider

Crab spider, species unknown

As I became more and more interested in insects, I learned that the vast majority of spiders really weren’t going to hurt me.  I knew that the wolf spider crawling up the wall or the little harmless brown spiders in the basement weren’t going to do anything to me, but the fear persisted.  I felt a little stupid for being scared of spiders when I wanted to become an entomologist because what entomologist worth her salt is scared of a little spider?  But I couldn’t help it.  They bothered me.  So, I arrived at grad school in the city of my birth imagining that black widows lurked in every corner and I would have daily encounters with all manner of huge spider.  Every now and again I would envision a spider crawling up the back of my couch while I was doing homework or something and it would make me shiver just a little.

crab spider

Crab spider

So, how did I get over my fear of spiders?  It all started on a class field trip along the border with Mexico that where there was a series of little ponds.  The desert is, by definition, a dry place where water is scarce.  Ponds are important to a huge variety of animals and there are often animals at any little pond you come across.  I wandered around one of the ponds looking for aquatic insects and happened to look down at one point.  The ground was absolutely covered in spiders!  Many different species were writhing about in a huge mass over the shores of the pond.  They were crawling all over my legs and I was scared at first.  But…  I also really wanted to scoop insects out of that pond.  So, I decided to ignore the spiders and keep collecting.  I let the spiders crawl all over my legs.  I let them crawl all over my backpack.  I didn’t worry about the fact that I might find a spider, dead or alive, in my pack when I got home.  I just went on with the more serious business of climbing into the pond to collect aquatics.  I wasn’t about to let some weenie little harmless spiders get between me and the aquatic insects in that pond!

Green lynx spider

Green lynx spider, pink phase (Peucetia viridans)

And you know what?  That was the end of my fear of spiders!  I don’t know how or why it worked, but I told myself to ignore the spiders and suddenly they stopped bothering me.  No more spider nightmares!  They can crawl all over me at those desert ponds and I don’t care.  Black widows are beautiful spiders and I love to watch them.  I enjoy seeing the big orb weaver spiders when I’m in the sorts of habitats where they’re found.  Sun spiders – spectacular animals!  And who doesn’t love a good jumping spider?  I might not pick spiders up, just in case I misidentify one I shouldn’t handle or have a strange reaction to tarantula hairs (those things make me itch like mad!), but I’m perfectly okay with spiders living in and around my house.  Sometimes I knock their webs down as I dust, but otherwise they’ve got a pretty good thing going living with me.  I just don’t care that they’re there.

All in all, I am happy I went on that field trip.  Forcing myself to walk through the spiders to get to the pond seems to have done me a world of good.  Now, if only I could get over my fear of centipedes…

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Unless otherwise stated, all text, images, and video are copyright © TheDragonflyWoman.com

Well-Nigh Wordless Wednesday: Spider and Young

I was involved with a conservation-centered biological survey of a Mexican ranch a few years back and I came across this spider as we toured around setting up sampling sites:

spider with young

A spider - with spiderlings!

I didn’t notice until I looked at the photos later, but the eggs were hatching while I was there and there were baby spiders everywhere.  Super cool – and such a spectacular animal!

(If anyone knows which spider this is, I’d love to know!)

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Unless otherwise stated, all text, images, and video are copyright © 2011 DragonflyWoman.wordpress.com

From the Literature: On Diving Spiders and Physical Gills

I love Twitter!  Since I’ve started using it, I’ve learned more about a wider variety of scientific studies than I ever did before.  It’s a great source of science news!  This story absolutely exploded on Twitter a couple of weeks ago.  I can see why it was so popular though: it’s a super cool story!  Aquatic spiders + special webs for holding air underwater = SCUBA spiders!  This story has it all.  It also happens to be closely aligned to my own area of expertise, so it’s time for another From the Literature!

This adorable little guy is the diving bell spider, Argyroneta aquatica:

diving bell spider

Diving bell spider. Image from http://www.nytimes.com/2011/06/14/science /14obspider.html?_r=1&smid=tw-nytimesscience&seid=auto

This spider is one of the only spiders in the world that spends its entire life underwater, from egg to adult.  Like its aquatic insect relatives, the diving bell spider has a number of adaptations that help it survive in water.  Its respiratory adaptations are especially interesting.  See that sheen along the abdomen of the spider in the photo?  That is an air bubble held in place by specialized hairs that trap air against the body when the spider surfaces.  Underwater, the spider can use that air store to breathe.  In addition to carrying the air film, this species does something truly spectacular: they build special silk webs underwater, fill them with air that they carry from the surface, and then use the air stored in the silk balloon (the diving bell) to breathe!  However, neither the air film carried by the spiders on their bodies nor the air contained within the diving bell are enough to completely satisfy the oxygen requirements of the spiders, so they depend on occasional surface trips to survive.

Scientists have known that these spiders use the diving bell as a sort of SCUBA tank for a while, but many questions remained.  No one knew what the oxygen conditions inside the bubble are, how much gas exchange occurs between the air inside the diving bell and the water outside, or how effectively the diving bell acts as a physical gill for the spiders.  (Please see my post Better Breathing Underwater in Aquatic Insects for a complete description of how physical gills work, why oxygen flows from water into an underwater air bubble, and why these air bubbles do not last forever.)  These unanswered questions drove researchers Roger Seymour and Stefan Hetz to look into the oxygen dynamics of the diving bell more thoroughly.  In the process, they discovered some exciting things about both the spiders and the unique air containers they build!

The researchers did several different things for their study.  First, they measured the volume of empty diving bells and used specialized oxygen detecting equipment to measure the oxygen levels both inside the bells and in the water surrounding them.  This information allowed the researchers to use mathematical equations to determine the potential rate of flow of oxygen from the water into the air bubble.  They also measured the oxygen inside the bubble while the spider was inside to calculate the rate of flow of oxygen from the diving bell to the spider, the spider’s oxygen consumption.  Using these two pieces of information, they could then show how effectively the diving bell acted as a physical gill, that is how long a spider could stay submerged when using a diving bell.  The researchers also measured the oxygen levels within the diving bells when spiders voluntarily returned to the surface  to reveal the oxygen level at which the respiratory requirements of the spiders were no longer met by the diving bell and they were compelled to replenish it with fresh air from the surface.  Finally, the pair measured the metabolic rates of the spiders directly using a respirometer, a machine that measures the amount of carbon dioxide released and/or oxygen absorbed by a biological organism.

Based on the result of all these measurements, Seymour and Hetz revealed several interesting things about the spiders and their diving bells.  First, they showed that the larger a diving bell, the more effectively it acted as a physical gill and the longer the spider could remain underwater.  Not only do larger bells contain more oxygen to begin with, but the flow from the water into the bell as the spider consumes oxygen is greater in larger bells than smaller.  Also, the larger spiders, those with greater oxygen requirements as measured with the respirometer, produced larger bells.  The authors further showed that diving bells easily provided the entire oxygen requirement of inactive spiders in warm, stagnant water (i.e., water with low dissolved oxygen) for over a day.  If the spiders moved around, built or cared for cocoons containing eggs  (cocoons are stored inside the diving bells!), ate prey that they captured, etc, then they had to return to the surface more often.  If they remained mostly still, the diving bell more than adequately provided their respiratory oxygen requirements for long periods of time.  Clearly the bells are acting as highly effective physical gills for the spiders!

Seymour and Hetz also demonstrated that the spiders stay within the diving bells until the oxygen drops d to 5-20% of the original level.  At this point, the bell apparently provides insufficient oxygen for the spiders and they return to the surface to collect air to replenish the diving bell.  The spiders also appeared to enlarge their bells if their oxygen demands increased or if the dissolved oxygen levels in the water dropped.

A few important implications are suggested by the results of this study.  The observations and measurements reported in the study were made in rather unfavorable conditions: warm, still water with low dissolved oxygen.  If diving bells are enough to meet the respiratory needs of the spiders for over a day under poor conditions like these, then spiders may be able to stay underwater nearly indefinitely in cooler and/or flowing waters.  This is important for several reasons.  If you happen to be an aquatic spider, you represent a nutritious meal to other aquatic animals such as fish, amphibians, and large insects.  Minimizing your trips to the surface, and thereby minimizing the attention you draw to yourself, is desirable.  It likely requires a lot of energy to make trips to the surface and back as well, so staying underwater as long as possible may help the spiders conserve energy.

diving bell spider in diving bell with cocoon

Diving bell spider in diving bell with cocoon. Image source: http://www.arkive.org/water-spider/argyroneta-aquatica/image-A12753.html

The spiders are also apparently able to respond to their environmental conditions and adjust the properties of their diving bells to match!  Seymour and Hetz observed their spiders enlarging bells under several conditions.  Spiders that captured prey enlarged their bells and added air to them before they started eating.  Spiders with cocoons also enlarged the bells as the broods inside developed, so the parents may be able to compensate for the increasing oxygen demands of their offspring as they develop by modifying the bell.  Apart from demonstrating how effectively the diving bell acts as a physical gill, I think the most exciting result from this study is that it reveals how these spiders intentionally modify their environment in response to their changing needs.

In summary, the diving bell does act as a physical gill for diving bell spiders as scientists have long proposed.  These bells allow the spiders to stay underwater for a very long time, and the spiders can adjust the bells to match their oxygen requirements and the dissolved oxygen levels of the water.  However, even under the most favorable conditions, the air contained within the diving bell will eventually need to be replenished, so the spiders will always depend on air from the surface and must have access to the surface to survive.

Super cool, right?  Aquatic spiders are amazing enough on their own, but spiders that build little air balloons to breathe underwater are infinitely more interesting!  Because I think it’s helpful to see it, I’ll end this post with a YouTube video (not my own) of a diving bell spider building a diving bell.  (I recommend turning the sound off – it’s got obnoxious music).  Enjoy!

Literature Cited:

Seymour RS, & Hetz SK (2011). The diving bell and the spider: the physical gill of Argyroneta aquatica. The Journal of experimental biology, 214 (Pt 13), 2175-81 PMID: 21653811

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Unless otherwise stated, all text, images, and video are copyright © 2011 DragonflyWoman.wordpress.com

The Nightmare After Christmas

Lethocerus as Santa

Santa Water Bug

Black Friday marks the start of the Christmas season, so I want to get a jump start on the holidays by sharing an entomological Christmas story with you!  This is no happy Miracle on 34th Street type story though.  Oh no!  This is more like Nightmare Before Christmas.  Except it happened after Christmas.  Hence the title.

Let’s start at the beginning.  About 5 years ago, I got a call from my dad saying that he was going to come visit me for Christmas.  I was ecstatic!  It was going to be the first Christmas I hosted at my house.  I was only going to have one guest and make a fairly small dinner, but I finally felt like an adult.  Imagine my subsequent disappointment when my dad told me a few weeks later that something had come up and he was no longer able to come visit me for Christmas.

So, rather than my first Christmas at my place, I ended up visiting my dad for a few days before Christmas, then went back home December 23.  Going home two day before Christmas to spend Christmas alone is a rather depressing activity.  I also knew my Christmas would consist of a trip to drop some friends off at the airport at 6AM and then a day at home alone.  I felt sorry for myself when I got back to my empty apartment.  I don’t like feeling sorry for myself, so I decided to do something fun to cheer myself up.  On Christmas Eve, I decided that the thing that bummed me out more than anything was not having the Christmas tree I was so excited about.  Then I went out and bought one.

The tree I chose was Canadian and maybe 3 feet tall.  It was kinda spindly.  It was shockingly expensive for a tiny, spindly Christmas tree that I bought after noon on Christmas Eve.  (Who else is still looking for a tree 12 hours before Christmas?!)  It had this little white piece of fluff near the top that I couldn’t get off.  I ended up calling nearly every shop in town trying to hunt down a Christmas tree stand and 2 hours later I finally tracked one down.  It was gigantic, the kind of stand we used for the 17-foot Christmas trees my family had when I was growing up.  The screws were barely long enough to hold the tree up and it looked ridiculous.  I didn’t care.  I lovingly decorated my tree with the little box of ornaments I’d collected since I first went away to college, wrapped tons of lights around the branches, and then stepped back to admire my handiwork.  I was really happy with the result (though apparently not happy enough to take a photo that was in focus – my apologies!):

Christmas tree

My first Christmas tree! I cleverly hid the flat, spindly side in the back. :)

Having my little tree made me feel so much better about being stood up on Christmas.  It made me really happy and I spent a lot of time staring at it. And, because I had bought it so close to Christmas and it was completely fresh, I knew it would last well beyond Christmas.  I was determined to keep it up as long as it lasted.  “Happy Valentine’s Day everyone!  Let’s gather around the tree!”  MY tree wasn’t coming down until it started drying out.

And then one day in late January, I woke up, walked into my living room, and realized in an instant what that little white fluff on the tree was.  I was greeted that morning by hundreds or thousands of tiny baby spiders crawling on a MASSIVE web they had built in my living room.  It was a spider egg sac!  The warm temperatures in my house must have let them hatch and then they started building.  The web stretched from the wall behind the tree clear across the room to my couch.  There were spiders all over my CD player, my insect books (oh, the irony!), the floor, the bookshelves, the art on the wall.  They were EVERYWHERE!

Now I’ll admit that I’m not a huge fan of spiders.  I’m good with a lot of them and don’t care if they crawl on me if they’re the right kind of spider, but they still elicit this serious shivers-down-the-spine creepy feeling on occasion.  And let me tell you, starting a lazy weekend morning off with thousands of baby spiders in the house sort of short circuited my brain.  I couldn’t get the tree out of the house fast enough!  Off came the ornaments, off came the lights, off came the tree stand, and the tree was flung hastily and utterly unceremoniously out the back door.  Then came the arduous task of vacuuming up the spiders and the web.  Two hours later, I flopped down on my couch exhausted, but secure in the knowledge that my Canadian spider scourge had been vanquished and my living room was once again free of the tiny arachnids.  Of course, I imagined them crawling on me for the next week, but what can you do.

And that’s my holiday spider story!  I hope everyone has a marvelous Thanksgiving and has fabulous plans for the upcoming holiday season!

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Unless otherwise stated, all text, images, and video are copyright © 2010 DragonflyWoman.wordpress.com