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Notes From The Field Blog




Autumn Spiders

Posted: 9/12/2013
Posted By: Tim Krynak
Original Source: Notes from the Field

Late summer / early fall is one of the best times of the year to look for spiders.  They have fed and grown all summer long and are now at full size and appear to be everywhere.  For some, just the word spider makes them nervous, and I bet these small animals are in the top three feared creatures in the world.  Most of this fear or dislike is a learned behavior from experiences early in our lives.  I remember growing up, any spider that made it into the house was quickly dispatched of by my Mom and a Kleenex. While she never screamed or made a big deal out of it, I know she is not a big fan of spiders.  I on the other hand like spiders.  While I would not say they are beautiful animals, I do find them interesting and best viewed under magnification to truly understand their complexity.


Cross Orbweaver

In Ohio there are 646 documented species of spiders (April 11, 2013) and the list continues to grow.  Here is a wonderful website on Ohio spiders and how anyone can help in the Ohio spider survey project. http//www.marion.ohio-state.edu/SpiderWeb/ Worldwide there are currently over 40,000 described spiders  species belonging to the class Arachnida, which also include: ticks, scorpions,  and daddy long legs.  To better understand the diversity of spiders they can be separated into many unique groups depending on shape, web design and behavior.  One easy way to begin organizing spiders is to look at how they capture prey.   All spiders do produce silk, but not all of them utilize silk in prey capture.  

  



Banded Garden Spider


The classic orb weaving spiders are what most people think of when envisioning a spider web.  The work of creating the web is repeated every evening, as many of the spiders in this group are nocturnal.  These are relatively big and showy spiders and are very common in meadows, around human structures, and in forests.  Their web consists of two main types of silk, but each species has more types available (web building, wrapping prey, egg sack production).   The silk that forms the structure of the web  is very strong and durable, and the rungs in-between have droplets of sickly fluid which entraps unsuspecting prey.


 

Orbweaver's web and wrapping up prey.


Probably the second most common web that is encountered is the “cobweb” which appears to be unorganized tangles of spiders silk found in our basements, garages, outside of our homes and are very common in forests.       


 

Cobweb Spider

There are other types of webs such as sheets, funnels, bowl and doily, and mesh webs.  I find the more interesting spiders are the ones that do not use webs to capture prey, but are ambush hunters.  They actively peruse their prey or sit and wait , well camouflaged in their surroundings to quickly pounce on an unsuspecting prey.  This group includes wolf spiders, fishing spiders, crab spider and jumping spiders, all with large well developed eyes. 

 

Bowl and Doily Spider



Jumping Spider


Crab Spider



My favorite group of spiders are the ant mimics.  These small woodland spiders are very abundant in the leaf litter on the forest floor.  Their resemblance to ants is amazing and most would think that they are not spiders at all.  They even wave their front legs to appear as if they have antenna like an ant searching for food.  Whether this adaptation is for protection from ants or a way to get close to a food source is yet to be determined. There are some studies that support both theories, proving we still have much to learn. 

 
Antmimic Spiders

Almost always when you start talking spiders there are two species that come up, the black widow and the brown recluse.  All spiders do utilize venom to subdue their prey and most do not cause more than localized discomfort, but these two can cause significant damage.   These two spiders are not frequently found in Ohio, as they typically are a more southern species.  They have been documented in shipments from the south in plant material, boxes or vehicles.

Whether you like spiders or hate them, the reality is that this group of animals is very important in the ecosystem.  Their control on insects is staggering and they in turn are utilized by predators like wasps and birds as food.  Their silk is used in humming bird nests as it expands as the nestlings rapidly grow, and ongoing research is promising that one day the mysteries of spiders silk will revolutionize the production of strong and lightweight building material.  The use of venom in medical research is important as compounds discovered maybe utilized in treatment of disease.  The spider is not to be feared but admired. 


 

 

Hummingbird Nest

There are so many interesting things to write about spiders, but I will leave you with a very interesting photo to ponder.  This is a gynadromorh which is half male and half female bi-laterally. 


  

 


Tim Krynak


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