Scanning Electron Microscopy of a Carpenter Ant

Ant Head - 144X

The head of a carpenter ant is made up of two compound eyes, biting jaws, and two bent or elbowed antennae that are used as organs of touch.  Contrary to popular belief, carpenter ants do not feed on wood, they merely nest in cavities of dead wood.

Compound Eye -  2000x

Antenna 1 -  360x

Antenna 2 -  1200x

Procedure:
The advantage that a Scanning Electron Microscope has over a light microscope is its ability to capture images at high resolutions and at greater depths of field. Depth of field is achieved in the way images are captured. An electron beam scans over the entire specimen and the secondary electrons are detected and displayed on a CRT screen. This increased depth of field gives the image a 3-D appearance. Resolving power is wavelength dependent, and as the wavelength decreases, the resolving power increases. Therefore the resolving power of an electron beam is much greater than that of a light beam. The benefits of increased depth of field and high resolution can be seen in these four images. To capture an image, manipulations in tilt angle, dynamic focus, working distance, spot size and acceleration voltage were applied. Images are taken from the light image generated on the CRT monitor and not the actual secondary electrons. The streaks seen in the image titled Antenna 2 are due to the high acceleration voltage.
 
 
Materials:
ISI Super IIIA Scanning Electron Microscope
Bio-RAD Polaron Division Critical Point Drying Apparatus, Model E3000
ISI PS-2 Coating Unit
Specimen: Carpenter Ant (Order: Hymenoptera, Family: Formicidae)
Polaroid Type 55 film (b/w, 4 x 5)
 

© Kirsa Upton
May 1999