Tuesday, March 15, 2016

An unusual spider

Sometimes you just get lucky.  Look at the picture below and see if anything catches your eye (not the hickory nut with a hole chewed in it):
Can you see evidence of a spider?
Now look at the picture again (below), in the shape I first found it.  This is a burrow in the ground I have been trying to find for a very long time.  It is the hole, and lid of a cork trap-door spider (Ummidia sp.).  Almost everyone has heard of trap-door spiders, but I bet most people did not know they lived in Ohio.  In fact, they probably live only in the extreme southern part of Ohio where the preserve is located.  I remember many years ago, one of the states Arachnologist's, Richard Bradley,  was very happy to hear that these cork type trap-door spiders were part of Ohio's fauna, and gave me the challenge of finding it's tunnel.  Pure luck brought me to this one.

Here the trap-door is open and you can see the spider's tunnel.
I have encountered, and collected a few of these spiders over the last 17 years, but I have never seen the actual trap-door and/or tunnel.  And if the lid wasn't open as I passed by this day, I would never have seen this one.  I saw the hole in the ground and assumed it was a burrow made by Geolycosa missouriensis, a burrowing wolf spider.  For some reason, this hole caught my attention and I thought I might stick a grass blade down the hole and see if I could scare up the wolf spider.  As soon as I got close to the hole, a lid shut and the hole disappeared.  It's still unclear whether I hit something, or shook the ground which closed the lid, or if a spider in the hole closed the lid as I approached.  But either way, I knew right then it was not a wolf spider burrow.  And seeing the thickness of the lid, and the silk lining the lid and tunnel, it was one of the trap-door species.

Here you can see the perfect fit of the lid and some silk on the lid and in the tunnel.
I didn't want this spider to abandon its burrow due to my poking and prodding, so I left it alone, and hopefully Rich Bradley will make it down to observe this unique camouflage method of hunting prey.  After we get our team of spider harasser's together, experiments will be conducted to see which one of us can fool the spider into jumping out of its burrow to attack whatever decoy is presented.  More to come if this is observed and recorded.

Below are two pictures of adult male cork trap-door spiders, Ummidia audouini, found on earlier dates.  I typically see them in the summer wandering about, maybe looking for mates.  They are intimidating in appearance, but if there is a spider that would make you say "Cool Spider", this is the one.

Cork trap-door spider, Ummidia audouini,  found last summer with Cincinnati Museum Center Science Camp students.

 Cork trap-door spider, Ummidia audouini, crawling on the wall of a building on the preserve.  This is a scan of a  photo taken 17 years ago.

I hope to observe the spider in the tunnel, or catch a glimpse of the trap-door in use in the near future.  Of course a post will follow if more discoveries occur and/or footage of this incredible mechanism is captured.  Stay tuned!

If you'd like to learn more about spiders, a great new guide,  Common Spiders of North America, written by Ohio arachnologist, Richard A. Bradley, is available on Amazon.com.  It's the best illustrated spider guide I've used and it encompasses a wide variety of spiders one might encounter. Rich is a wonderful teacher and also has a spider website found here: http://spidersinohio.net/

Posted by Mark Zloba