Friday, July 27, 2012

A Flesh Eating Predator (Less than 3 mm long)

In my previous blog post I showed images of Lantana montevidensis.  When I brought the first sprig of Lantana back to the lab a small spider came along for the ride. Because so many different kinds of insects live on and in the Lantana, it makes sense that it would be a good a niche for a tiny predator.

This spider is less than 3mm from the most anterior part of its cephalothorax to the posterior end of its abdomen.

This is not a very detailed study because this is the first spider I have tried to image with the scanning electron microscope.  I had a problem with the build up of charge on the spider (which distorts the image). I will have to do some research and experimentation to figure out how to keep this from happening. 

Never the less, the following images should give you a feel for the marvelous strangeness of spiders - some of my most favorite creatures on the planet. 

Spiders this size can be frustrating to study - I have tended to avoid them. 
Now, thanks to my access to an SEM that will change. [22x]

A closer look at the abdomen [50x]
You may notice the absence of spinnerets on the posterior end.  On this species they are on the ventral surface of the abdomen.

 At 177x ridges on the abdomen become visible.

Dorsal Abdomen [384x]

 A look at the pedicel that connects the cephalothorax (right) to the abdomen (left) [255x]

 Cephalothorax and eyes [90x]

 Cephalothorax and eyes [160x]
Ridges become apparent

Talk about a head shot!  [471x]
I wonder where they got the ideas for Spider Man's costume?

 Femur of the hind most leg on the right side of spider [350x]

Patella at top, Tibia below [200x]
Look carefully and you can see three distinct type of hairs. 

Close up of hair types on tibia [903x]
Affect of charging is obvious - I am going to work on this.

Many years ago I had the opportunity to develop and teach an arachnology course to high school students.  I will be honest, studying spiders is difficult, but we made some progress and my students and I really enjoyed it.  When I changed schools, unfortunately, there was no interest in the class, so I haven't done a lot of spider work for some time.  Chancing upon this little spider has definitely rekindled my interest.

If you would like a chance to see and use a scanning electron microscope to image spiders or anything else, please don't hesitate to contact me.  Eastfield college is dedicated to supporting work in the STEM fields at all levels - for both faculty and students.  If you are not located near Eastfield College, we can still collaborate online.  I Skype.  Hope to hear from you soon.

Murry Gans
Scanning Electron Microscope Lab Coordinator
Eastfield College

It All Begins Here!

Lantana montevidensis

On my way the administration building I came across what my wife and I call butterfly weed.  My online research reveals it to be Lantana montevidensis (at least that is what I think it is).

It turns out that it is not a butterfly weed at all - that will teach me to use a common name - especially one I make up.

I reach down and cut off a sprig with my pocket knife and head back to the lab, then return with my camera to get a few pictures

It may not be a butterfly weed, but butterflies sure like it. 
This swallowtail came for visit while I was taking pictures.

Next it is on to our dissecting scope for a closer look.

Nice long tubular flowers - made for butterflies, and butterflies made for it!

 Butterflies aren't the only insects that like this plant.  On this close up you can see a small insect in the picture.  I was lucky to catch him - the capture rate on the camera is pretty slow.  By the time I could take a picture he would scurry away. (The colors you see on the insect here are because of chromatic abberation - very pretty though.)

Finally got him.  True colors this time.  I don't know his genus and species, but he is definitely a hemipteran or true bug.

 Flower head straight on.  Notice the small hairs just inside the tube. 
You will see these again on the scanning electron micrographs.

 Yet another resident on this flower living inside the tube of the flower.

 Here is a leaf from plant - just for the record.

On to the SEM.  I didn't collect and image the insects.  I actually work backwards - SEM first, then camera and dissecting scope.  I didnt' even know the insects were there until these images were made.  I wouldn't have collected the butterfly anyway - it is hard to kill something that beautiful.

 For this image I split the flower open. 
You can see the layer of hairs just inside of the tube and farther down are 4 stamen. [13x]

 In this image you can see the stamen, another field of hairs, and then the stigma.  [25x]

 Stamen [55x]

A close look at the cells that make up the tube of the flower. 
This is a close up of the section seen on the right hand side of the image above. 
At the bottom is one of the "hairs" inside the tube. [691x]

Cells of the stamen.  Where is the pollen?  [150x]

 Make up of a petal - the part in focus is the outside of the petal folded back on itself [101x]

Close up of cells that make up the petals.  [470x]

 Upper surface of leaf [60x]

Closer look at upper surface of a leaf [250x]. 
I simply cannot believe how alien this appears.

 Bottom leaf surface. 
The tree-like structure running left to right is the midrib.  Stomata are visible.
The globular structures must be glands that contain aromatic liquids. [150x]

 Bottom leaf surface [250x]

Stomata on bottom of leaf [800x]
Distance between marks on scale = 5 microns

I welcome you comments on this posting.

If you are interested in using the SEMs at Eastfield or would like for me to bring the portable SEM to your school, please contact me. 
Eastfield is dedicated to the support of research in the STEM fields by students and faculty at all levels.

Murry Gans
Scanning Electron Microscope Lab Coordinator
Eastfield College

It All Begins Here!

Tuesday, July 24, 2012

Copper Wire - Cooler than it sounds (at 5,000x)

An undesirable phenomenon called charging can occur when using a scanning electron microscope.  The electrons from the electron gun need a conductive pathway.  Nonconductive specimens will accumulate a charge - they become very bright on the screen.  The worst part is that at some point they will discharge which can distort the image.

There are lots of ways to deal with this, like reducing the gun voltage, but I wanted to try my hand at using some high voltages.  My solution - use copper wire. 

I found an old telephone line, opened it up and stripped the insulation off one of the small wires inside.  (I used a pocket knife - not such a good idea as you will see.)

Here are my lovely copper wires at 37x  (Gun voltage = 15kv)

A closer look at 1,000x

At 5,000x the smooth wires are looking a little rough.
Notice the striations that show where the wire was drawn through the die.

All of the images above were made using the secondary electron detector, thus the "SE" on the bottom of the picture.  SE images are made in a high vacuum.  The problem is, I purposely left some the insulation on the wire.  Talk about charging!!  Another solution to the charging problem is to use the back scattered electron detector.  This detector can work in a partial vacuum.  That little bit of air can solve the charging problem.  Notice on the images below the "BSE" as well as the atmosphere in the scope.  In the next image shows an atmosphere of 6 Pascals.  (Standard atmospheric pressure is 101,325 Pa.)

 Why you shouldn't strip wires with a pocket knife (42x)


Copper is soft.  Looks like I have effectively reduced the diameter of the wire by half. (400x)

 Back to SE mode at a lower voltage.  The surface of the wire shows what appears to be crystallization. (1,600x) I am going to have to go back to the lab and take another look. 

Have something you would like to see up close and personal?  Give me a call.

Murry Gans
Scanning Electron Microscope Lab Coordinator
Eastfield College

Sunday, July 22, 2012

Popcorn Revealed

The scanning electron microscopes at Eastfield College are available for use by any student or faculty member free of charge.  In an effort to advertise this fact, once a week I take our small scanning electron microscope to the "Pit" so students, faculty, and staff can see it in action.

The Student Life organization at Eastfield is kind enough to come each week and give away free popcorn while I am there.  (It is dang good popcorn, by the way!)

Last week a young man, I am guessing Middle School aged, was eating in the Pit with his dad and came over to see what I was doing.  We dediced to put a piece of popcorn into the scope and see what it looked like.  Below are the images we made.

 Image 1:  Outer side of popcorn [30x]

Image 2:  Outer side of popcorn [250x]

Image 3:  Outer side of popcorn [1,200x]

 Image 4:  Inner side popcorn kernal [30x]

Image 5:  It is salted popcorn!! [250x]

It is pretty obvious that nature loves hexagons.  What first struck me was how much these exploding hexagons of starch look like the cells in a bee hive.  Bees build in hexgons because they can be tesselated - placed together with no wasted spaces - and because it allows them to build the largest volume for strorage with the least amount of material. 

I continue to be astonished by what the scanning electron microscope is able to show me.  Call and come by Eastfield and see what you can discover. 

Murry Gans
Scanning Electron Microscope Lab Coordinator
Eastfied College

It all begins here!