Tuesday, August 21, 2012

Itsy Bitsy Spider - The Scanning Electron Microscope Version


Even if you aren't interested in the biology of spiders, please check out the images in this blog posting.  These small and often loathed creatures have some of the most remarkable anatomy you will find on the planet, and they are in the most mundane places - like around the porch light in my backyard.

In my previous blog (August 20, 2012) I showed images of a small Theridiid - a cobweb spider.  The images in this posting were made with the scanning electron microscope here at Eastfield College.

 
Prosoma (Dorsal)
70x
A shot of the dorsal surface of the cephalothorax or prosoma.  Even at 70x you can immediately see that this spider does indeed have 8 eyes, not just the 6 I thought I saw with the light dissecting scope.
 
Prosoma
178x
Several hairs on the prosoma and one obvious sensory pit.

Sensory Pit
3,500x
Small sensory pit on dorsal surface of prosoma.  Distance between marks on scale = 1 micron.
 
PME
503x
Spiders do not have compound eyes like insects.  This image is of the PME or median eye on the posterior eye row.
 
Dorsal Opisthosoma
320x
Image of the peak of the opisthosoma or abdomen.
 
Anterior Opisthosoma
190x
To make this image I rotated the spider so he was facing me - the bright structure at the bottom of the image is the prosoma.  Basically I was shooting electrons right over his head and onto the abdomen.


Side portrait
47x

Pedicel
250x
This is a side shot of the spider focusing in on the connection, or pedicel, between the two body parts.  In this image the spider is facing to the left.  Prosoma to the left, opisthosoma to the right.

Prosoma or cephalothorax
90x
The dyad of eyes (pairing) is very obvious in the micrograph.  The dyad is composed of the ALE and the PLE - the lateral eye of the anterior eye row and the lateral eye of the posterior eye row.

 
ALE/PLE Dyad
400x
The dyad is composed of the ALE and the PLE - the lateral eye of the anterior eye row and the lateral eye of the posterior eye row.

Ventral Abdomen - Epigastric Furrow
60x
  
Epigastric furrow and epigynum
300x
Ventral view of anterior region of abdomen of opisthosoma.  The large fold across the photo is the epigastric furrow and the opening with the concentric rings around it is the epigynum, or reproductive opening of the female.
  
Epigynum
804x

Spinnerets
200x
There are three pairs of spinnerets.  Most obvious are the large, paired anterior spinnerets at the top of the image and the large, paired posterior lateral spinnerets just below them.  (The football shaped structure at the bottom of the spinnerets is the anus.)  Not so obvious are the smaller, paired posterior median spinnerets between the larger PLS.
 
Anus and Posterior Spinnerets
471x
Posterior lateral and median spinnerets at top of image.
  
Close up of Median Posterior Spinnerets
1,090x

Portrait
19x
I wanted to image the spider head on so I draped its front pair of legs over the mount.

Theridiid Head Shot
46x


Eye Arrangement
230x
Image of the two row of eyes on this spider - the anterior eye row (AER) and the posterior eye row (PER).

Close up of Posterior Median Eyes (PME)
470x
Note the sensory pits above the eyes.
Now for some basic spider leg anatomy! 
This study focuses on the second leg (simply because it was in the proper position).

Coxa and Trochanter
219x
The coxa is indicated by the red arrow and the trochanter by the blue arrow.


Femur
70x

Patella (Knee)
190x
 
Tibia
80x

Close up of hairs on tibia
422x

(Drat!!  I just figured out that I became fixated on the hairs on the tibia and didn't image the last two segments of the spider leg, the metatarsus and tarsus.)


Egg Sac
30x
In this image the egg sac has been teased open showing the spiderlings inside.  In the upper right of the photo is a spiderling who was outside of the egg sac.

[Technical note:  The difference in brightness of the top and bottom parts of this image is caused by the specimen accumulating a charge.  Spiderlings at the top of the photo were not in contact with the mounting so they became negatively charged, which causes them to glow.  Not what I would have liked, but still an interesting image]


Spiderling Portrait
120x
Distance between marks on scale = 40 microns.  This guy is little!
 
Egg Sac Silk
750x
 
Egg Sac Silk
2,100x
Diameter of silk strands less than 2 microns

After two days of imaging and a couple of days of selecting images for the last two blogs, I can truthfully say that I have totally satisfied my spider jones . . .  for now. 

Eastfield College is more than happy for you to use our scanning electron microscopes to satisfy your own curiosity whether that be biology, physics, or chemistry.  We provide the SEMs, you provide the specimens.  All you have to do is contact us.

Murry Gans
Scanning Electron Microscope Lab Coordinator
Eastfield College
Mesquite, TX
972-860-7267


3 comments:

  1. This is the most amazing blog I have ever seen!! (Actually, this is my blog. I just thought if I commented it might encourage others to do the same.)

    ReplyDelete
  2. It's awesome Murry. Thanks so much.

    ReplyDelete
  3. Amazing pictures, thankyou for posting

    ReplyDelete