SEM Image PortfolioSean Coughlan

May 3, 2016Biology 211

A

B

Beetle WingAccelerating Voltage: 10 kVWorking Distance: 24.0 mmSpot Size: 400Magnification: 200xNotice the charging to the right of the image, indicated by the arrows A.

Above is a micrograph taken at 200x magnification of the outer wing, or elytra of a lily beetle, Lilioceris lilii. The lily beetle is an invasive species originally from Europe and Asia which has caused disastrous impact ravaging both personal and commercial lily cultivations. Much of the beetle’s skin is covered in pores, seen in large numbers above, used for secretion, labeled B.

C

Beetle WingAccelerating Voltage: 10 kVWorking Distance: 24.0 mmSpot Size: 400Magnification: 1500x

All beetle’s all have two sets of wings, the inner flight wings, and the outer elytra, which are used for protection of the flight wings as opposed to assisting in actual flight. In addition to the pores, notice the hairs, or setae, coming out of the elytra, seen in the center of the screen, marked by arrow C.

D

E

Beetle WingAccelerating Voltage: 10 kVWorking Distance: 24.0 mmSpot Size: 400Magnification: 5010x

As magnification increases, the amount of particulate matter becomes more apparent, as do artifacts such as charging, seen at arrow D. Beetle cuticles have a number of different features, such as the previously mentioned pores and hairs, as well as tubercles, or bumps, labeled E.

FF

Beetle WingAccelerating Voltage: 10 kVWorking Distance: 24.0 mmSpot Size: 400Magnification: 7510x

It should now be apparent that as magnification increases, resolution will decrease, best exemplified around the edge of the tubercle. Additionally notice the indentations which become more apparent with the increased magnification, some of which are pointed to by arrows F.

A

A

A

Betta Fish FinAccelerating Voltage: 10 kVWorking Distance: 25.0 mmSpot Size: 400Magnification: 5010xCharging artifacts are present across the image, causing blurriness, indicated by arrows A.

Above are the scales of the Betta fish, or Betta splendens. In general, fish scales are divided into four types, Placoid, belonging to cartilaginous fish, Ganoid, belonging to sturgeon-like fish, Elasmoid, belonging to bony fish similar to the coelacanth, and Leptoid, belonging to most bony fish. Leptoid scales can further be divided into two types, Ctenoid, and Cycloid, seen above.

B

Betta Fish FinAccelerating Voltage: 15 kVWorking Distance: 25.0 mmSpot Size: 400Magnification: 5010xCharging artifacts are present in the same locations as the previous image.

Looking at the comparison between the two images as accelerating voltage increases from 10 kV to 15kV, it can be seen that there is a large increase in the charging across the image. However, the resolution is increased in the second image as well, best exemplified by the arrow B.

Lily LeafAccelerating Voltage: 10 kVWorking Distance: 24.0 mmSpot Size: 400Magnification: 5000xCharging can be seen along the extremely bright particulates in the left of the image, indicated by the arrow.

Seen above is a stoma of a lily leaf, genus Lilium, at a spot size of 400. Stomata are pores located along the epidermis of plants and used to regulate gas exchange. Along both sides of the opening are a pair of cells known as guard cells, which regulate the opening and closing of the stoma. In this case the stoma is partially open, with the pore not being fully open nor closed.

Lily LeafAccelerating Voltage: 10 kVWorking Distance: 24.0 mmSpot Size: 300Magnification: 5000x

As the spot size is decreased to 300 from 400, the most obvious change is the increase in noise, due to the smaller number of electrons in the beam, as well as the lower resolution creating a less clear image. Notice the large number of apparent particulate matter, which are just noise caused by the lack of electrons.

Phlox PetalsAccelerating Voltage: 10 kVWorking Distance: 24.5 mmSpot Size: 400Magnification: 1000xNotice the large amount of destroyed cells to the right, likely an artifact of fixation.

Phlox are a North American perennial flowering plant of the family Polemoniaceae characterized by their numerous flowers and the large number of color variations. Seen above are a number of the cells of the flower petals. Notice the ridges, or cuticular folds across the cells.

Phlox PetalsAccelerating Voltage: 10 kVWorking Distance: 10.5 mmSpot Size: 400Magnification: 1000x

Looking at the effects of the decrease in working distance from 24.5 to 10.5, the clearest change is the decrease in depth of field. Examining the cuticular folds, one can see how they are in much less detail then previously. Additionally, resolution has increased, most easily seen by examining the spaces in between the cells and the edges of the cells.