Thursday, November 14, 2013

The Acorn Weevil, the Creature Designer, and an SEM

I just received a very kind e-mail from an unusual source.  Lars Grant-West is an illustrator and creature designer, as well as a professor at the Rhode Island School of Design.  Is that cool, or what!  He was prepping for his Creature Design class, which is currently focusing on arthropod limbs, when he found my blog. 
Today's blog post is for Lars and his students.

A few weeks ago I asked Jeff Hughes, one of the biology professors here at Eastfield, to be on the lookout for "snout beetles" while he was in the field.  Jeff is a good guy and he collected some "snout beetles" for me, but not the ones I expected.   He brought in some acorn beetles.  Acorn beetles are actually very common - I had just never come across them before. According to the Texas A&M University AgriLife Extension website "Acorns of live oaks in urban areas of North Central Texas are sometimes 100 percent infested by larvae of acorn weevils."

Once I began imaging them, I realized that this was one of the must unusual and beautiful insects I had come across.  (Yes - I am a nerd.)

Take a look and see what you think.

(All of the color images below were taken on the Leica digital dissecting microscope.)

This is my new favorite insect and this is my new favorite image.  My students say this looks like the guy from the movie Despicable Me.  Note that this little fellow is covered with bright yellow scales.
Here you can see the weevil attached to the side of a Petri dish.  The easiest way to imagesmall, live insecs is inside of a new plastic Petri dish - they have a limit area in which to move around and the plastic doesn't seem to affect the image.
That beak!!  The mouth parts are at the very tip and are used to burrow into acorns.  The weevil sucks out some of the nutrients in the acorn through its tubular snout for a meal and then lays an egg inside the acorn.  It seals off the hole with its poop.  How is that for parental care!

Notice that the elbowed antennae don't come off of the head, but off the snout.  If  you have a long snout and need to find juicy acorns to eat, I guess those antenna need to be closer to the action.
In this image the weevil is hanging upside down to the top of the Petri dish.  Note the delicate articulated antennae.

A closer look at the antennae.

In this image the weevil is walking upside down on the top of the Petri dish.  Notice the yellow, brush-like structures on each foot.  These are setae which provide lots of surface are for sticking to surfaces - a very common solution in biology.

Here is a close-up view of the setae on the foot pads of the weevil.  The trick here is to have enough total surface area to be able to stick to a surface, but to also be able to release the foot for walking.  Evolution at its best.
Now let's move on to the scanning electron microscope for a closer look.  (Unfortunately, one of my students made some changes on the way images are saved which meant I lost the usual scale bar on the bottom of these electromicrographs.  I was able to recover the magnifications and added it to each image.)

Hello there.  Note the numerous scales.  The structures under the snout are antennae.  [32x]
I am obsessed.  I love this image. [85x]
Now if you would just look to the left for this next shot.  [75x]
Eyebrows?  65x
The ommatidia of the eye.  [994x]
A side view of one of the feet of the weevil.  [30x]
A close look at the setae on the foot pad.  You can see two different types - needle-like setae on the margin of the pad and spatula-shaped setae in the center.  Also notice that the setae appear to be in groups - this actually increases their ability to stick to surfaces. 

The tips of the antennae [65x]

This is the joint where the antennae are attached to the snout.  Looks like a ball and socket joint which should allow for lots of movement. [65x]
The tip of the snout.  Notice the lovely little pollen grain just above and left of center.  These are the jaws of the insect.  [230x]

A top down (dorsal) view of the insect.  In this image you can see how the insect is mounted in the SEM.  Wood glue!!

This is the point where the thorax of the insect meets the abdomen.  The head would be at the top of this image.  This guys is covered with scales.  [75x]
Scales at 150x.

The elytra that cover the wings - dorsal view. [32x]

In this image you are looking at the underside of the insect and can see the ball-and-socket attachment of the legs to the body.  [32x]

A closer look a the leg-body attachment.  Also notice the small canal or hole.  My guess this is for hearing - but that is just a guess.  I will have to find out.  [150x]
The Acorn Weevil is my new, favorite insect and I hope an inspiration for Creature Designers everywhere.

As always, all images are under a Creative Common License.  Feel free to download, upload, use and abuse - just give Eastfield College as the source of the image.

Murry Gans







Monday, July 29, 2013

Scarab Beetle - Beautiful, even if you don't like insects.

I like insects and spiders.  My colleagues in biology do too, but the majority of people out there seem to have a universal response when I mention insects - "Yuk"!  I am almost certain that these "yuk" people have never looked at an insect closely because if they had they would find some of the most unusual and beautiful creatures on the plant.
Last week, Cyndi, who works in our division office here at the college, brought me an awesome scarab beetle from her yard.  This little guy will definitely make you take a closer look the next time you see an insect.
Below are some of the images I took of this beetle with my point-and-shoot camera and with the digital dissecting scope in the Microscopy Lab.  The dissecting scope images are first.

Something with such amazing colors lives in Dallas County? Absolutely!

Notice the club-shaped antenna with three sections.


As you can see, this little guy is alive and holding on to a twig.  It has very large tarsal claws for gripping.


Here you can see the tarsal claws and that all parts of this beetle are beautifully colored.

I wanted some more images of this beetle so I saved him a piece of lettuce from my deli sandwich and took him outside with my point-and-shoot camera.  This allowed much better depth of focus.

Notice the horn in the center of the head. 

A closer look at the eyes and horn.

A good look at those tarsal claws.


Last and one of the best. 

You may notice that there are no electron microscope images of this beetle.  The inside of an electron microscope is a very inhospitable place to be -- the high vacuum dries specimens out very quickly and there is high energy beam of electrons.  I could have killed the beetle and mounted him in the scope, but some things are too beautiful to destroy and, I hope you will agree, this insect is one of them.  I released him this morning, alive and well.

Bizarrely beautiful, but definitely not yukky.

As always, I welcome comments on this posting. 

Thursday, May 9, 2013

How Sharp is a Hypodermic Needle?


This week I had a group of students from a local high school visit the Microscopy Lab here at Eastfield College.  One of the students, who has a parent who is a physician, brought in some unopened hypodermic needles. Not being one to pass up an opportunity to use our scanning electron microscope I thought I would take a look.

I imaged two different sizes - a 19 gauge and 25 gauge needle.  It is going to seem weird to some of you (including me) but the lower the gauge the bigger the needle.  The 19 gauge needle has a surprisingly large bore needle.  It looks like the ones they use when I donate blood and is larger than one that would be used for a regular intramuscular injection, which is the 25 gauge needle. 

This side by side comparison will show you the apparent differences in the size of the two needles.

[20x] - 19 gauge 
Here is a look at the business end of the larger needle.  I strongly suspect that the specks on it are entirely my fault.  I photographed it and had it in the lab for a while before I got it in the SEM.  I am sure it was perfectly sterile when I first opened it.  Obviously, I do not run my lab under "clean room" conditions. 

[55x] - 19 gauge 
Two things show up in this image that I find interesting.  First of all, you can see that the point is made by two separate cuts.  The cut that makes the tip is more acute than the one above it. Second, you will see that the interior of the needle has a pretty rough texture.
Here is the tip of the 19 gauge needle.
The tip of the 19 gauge needle
At 1,600x the tip of this needle looks like a jagged piece of shrapnel.  But take a look at the scale at the bottom of the image.  The entire length of the scale is 30 microns which means the distance between marks is only 3 microns - that is 3 millionths of a meter.  Bottom line, this is really sharp.
Here is the inside of the barrel of the needle.
Same spot - higher magnification.

Same spot again.
Above is the smaller 25 g needle.  The base of the needle is cut at a steeper angle which would make it sharper.  You can see that the tip is also made with two cuts at different angles.

Here is the tip of the 25 g needle.  Looks kind of blunt but it really isn't on the macroscopic scale.

Same image but with a direct measurement.  Both of the lab's Hitachi SEMs are calibrated to make measurements on images.  Pretty cool.

I noticed that the top of the bevel was not a nice oval shape.  Lets look a little closer.

You can see that a thin layer of metal has been folded back during the manufacturing process. No worries - this is so small that you wouldn't feel the difference.

In this image you are looking straight into the sharp end of the 25g needle.  The tip is a little to the left of bottom center.  You can also see the two bevel cuts that make up the point.  I added the measurement to show you what a neat job of engineering this is.  That hole down the middle is 1/64th of an inch in diameter!!
Here is some not so pretty engineering.  To get these needles into my SEM I needed to cut them off.  I didn't have any wire nippers so I used a pair of pliers and simply bent the metal back and forth until it broke.  You are looking at metal fatigue.
The images made by Eastfield College Microscopy Lab may be used, saved, uploaded, modified, or linked just as as long as you give credit to Eastfield college.  The only restriction is that they may not be sold.

Murry Gans
Eastfield College
Mesquite, TX