Monday, March 23, 2009

Diatoms under a Scanning Electron Microscope

This is a colorized scanning electron microscope image of a sample of freshwater diatoms collected from a creek in Pennsylvania. Diatoms are a type of algae and are commonly found growing on the glass of fish tanks. In nature they are the brown coating on rocks in a stream, or any body of water on earth. There are thousands of types of living diatoms and probably millions of types in the fossil record. The diatoms are mainly constructed from silicon dioxide – commonly called quartz by geologists. This very rugged and stable material allows the skeletons of these microscopic animals to become fossils.

It is near impossible to sum up the topic of diatoms in a short space. As a group they have a very rich scientific history as they have shaped both geology and biology studies. Specimens mounted on microscope slides were viewed for entertainment in Victorian England. There is little doubt that their variation in form and shape makes them interesting to study.


Recently I was asked to photograph a large number of microscopic organisms in the modern HDTV format. It has been at least ten years since I photographed many of these species, so it was nice to return with modern cameras and see what I could do. The Vovlox is a favorite of students, looking like a geodesic dome with replicas of itself in side; it is really a form of algae. When students first look at microscopic algae they think it will just be stationary but the opposite is true. Volvox are very fast moving, each of the cells has two tails that help with transportation. The cells all work together in a colony that spins and bumps through the water. Volvox is a freshwater algae.

Sunday, February 8, 2009

Monarch Butterfly Egg

Some science images are easy, and some are very complex. This is a scanning electron microscope image of a Monarch Butterfly egg case is a very difficult picture. Just the sample preparation of this image took over a week. For years I have collected butterfly eggs, usually for my young kids. We will have a bottle with several eggs that hatch into microscopic worms that feed on milkweed leaves. In this case my kids and I went for several hikes in the finger lakes region of New York. After a few hours of looking on every milkweed plant we saw, we were able to find three eggs. The eggs were placed in a dilute solution of alcohol and the alcohol solution was slowly increased in strength until it was at 100% - a week later. The egg is then placed in a high pressure solution of carbon dioxide gas to remove all the water. This process is called critical point drying. The egg was then coated with a conductive layer of gold in a sputter coater. At this point the egg is ready for the scanning electron microscope (SEM). Since the microscope only collects a black and white image, the image needs to be colorized using Photo shop. The coloration process itself can be very complex. For this egg image I used two different images – one image contained the red part of the image, while the send image contained the blue data.

Popping a balloon

This is one of my favorite images and like most science images it has a story behind it. This image was taken during an assignment for a British science magazine. The magazine requested a young girl popping a balloon and needed to show the human reflex of closing your eyes near a loud noise. I used my then 7 year old daughter for the shoot. After it was over my assistant Roger was playing around with over-inflating a balloon until it burst. This does take a good set of lungs. After a few test shots we were able to get this shot. Balloons do not always burst like this, but this one in particular turned out nice. The balloon had a teaspoon of water placed inside of it. The water is in the gas phase when the balloon is inflated, but when the balloon pops, there is a sudden drop in pressure that creates a cloud. The resulting cloud lasts less than 1/1,000th of a second. The action was captured by a high speed flash that had a duration of 1/20,000th of a second. Many interesting science photos are taken by messing around in the high speed photo

A drip of water.

This is a relatively simple image of a drop of water. The images from a simple drop are dependent on the speed of the drop in this case the height it falls from, the viscosity or the fluid, and the depth of water the droplet falls into. The time the image is taken after the collision with the surface will also greatly influence the image. If the high speed flash it triggered too soon, the droplet is still in mid-air. Too late, and the collision is over. The set up involves placing a pipette about two feet above a shallow pan of water, as the drip falls though an infrared light beam, a microprocessor starts counting time. After a specified time a high speed flash is triggered. This image represents a slice of time of 1/20,000th of a second. This is often called freezing time, this image looks like frozen water.
The simple collision of a drip of water and a surface is actually quite complicated. The physics of this situation influences everything from an ink jet printer to an industrial water cutting jet. The fluid dynamics has fascinated many scientists over the years, but Dr. A.M. Worthington was so taken by the process that he wrote two books on the topic in 1908. These books were compiled from his earlier lectures and greatly influenced the use of high speed photography. In the coming weeks I will write more about high speed photography.

Sunday, February 1, 2009

Love is in the Water

Reproduction is one of the driving biological forces and often commands readers attention. This photo shoot was done under difficult conditions. Toads are one of the first amphibians to mate in our northern climates and often beat out other species by a month. Here in New York these toads will only mate for two days in the ice cold waters in the early days of April. The mating starts at dusk and is most active if there has been rain. So there you have all the conditions that make up an enjoyable photo shoot – 40 degree weather, light rain, dark, and I am wearing a wet suit and in water knee deep. On this photo shoot I also had an assistant holding a remote flash as I used the underwater camera. The goal was to get a solitary male with a huge inflated air sack as the male calls to the females. The males call in the females, as well a jockey for prime territory. The females will answer with a deeper sound, and I am sure there are frequencies involved below the human hearing range. The males will often mount another male, but with out the correct sounds will quickly identify that something is wrong and go back to calling. Once the male finds a female and is accepted he will hold on until the female lays the eggs and external fertilization takes place. After three nights the mating was over and I still did not get the shot I was seeking – I will return this spring.

This image shows the male firmly positioned, awaiting the egg laying . The male is on top while the female is on the bottom. The female is larger than the male due to she has to carry a large percentage of her mass in eggs. On a rainy night in the summer you can collect toads hopping on the roads. If you take the weight of each of the toads you find and make a bar graph of number of frogs vs their weight - you will see the data points are bunched together. Such a graph will show the average weight a toad gains each year – thus you can determine the age of a toad that you find. The oldest toad I have found was six years old, although I suspect there are older ones. The especially large toads I run across I call toadzilla.

Sunday, January 18, 2009

Southern Pacific Rattlesnake x-ray

Full Snake X-ray

While working on the rattlesnake fang project I mentioned to a friend about the snake heads in the freezer. He offered me several more! It turns out that if you own an expensive home in the hills outside of Santa Barbara in California you often keep rat traps to help keep the rats out of your house. This is a southern pacific rattlesnake that wandered into a rat trap. Of course I said I would love to have it and the next morning the dead snake arrived in the mail. I drove over to the university and x-rayed it in the high resolution machine. Hard to see in this image but there are a number of broken vertebrae several inches from the head. This snake is about 20 inches in length.

Freak Snowflake

Freak Snowflake

For many years I have photographer perfect snowflakes. I do not live in the best location to photograph snowflakes, since I live near Lake Ontario in New York. Our most common (98% of the time) show is lake effect. The lake effect snow is a jumble of little fast forming crystals and is as far from photogenic as snow crystals can get. Many snow crystals are not perfectly six sided, but have weird angles. I call these freak flakes, and I will often photograph them when I see them. No mater how weird a snow crystal looks, it still tries to maintains a electrostatic symmetry. In this case the little captured snow crystal on the left carried enough electric charge to balance out the weird arm on the right. In the world of snow a snow crystal is a perfect single crystal of water while a snowflake is made up of a group of snow crystals. This image is technically a snowflake – can you find all the individual crystals?

Rattle Snake Teeth

I was asked by a medical textbook author to take a few pictures of hollow rattlesnake fangs that were supposedly the inspiration for modern medical syringes. Easy to get fresh rattlesnake heads, just call up the biggest supplier of rattlesnake meat. Located in Georgia, the company shipped me several fresh snake heads for a few dollars. The largest was the size of a 200watt light bulb. Quite a large snake to find in the wild. Before I extracted the teeth, I stopped by one of the research radiography laboratories at one of the local universities where I often use their high resolution x-ray machine. I was surprised to learn that rattlesnake teeth are like sharks. The snakes are constantly looking and regrowing new fangs. It turns out that a rattlesnake will go through a set of fangs on average every meal and a half. In this side view of the head you can clearly see several sets of spare fangs in the upper jab. This is one of the fun things about being a science photographer, I am always learning new things.

Thin Film Soap colors

Thin Film Soap colors

Many time a research paper will be published that will show a unique scientific experiment. I was reading a technical paper on fluid flow where the research was done with one color light to measure the thickness of the soap film for flow analysis. I modified the experimental setup to use white light, thus showing different thickness of a soap film as a different color. This image is a still from a video series showing fluid flow. The soap flows out of a reservoir between vertical wires that are pulled apart so that the resulting soap film shows optical interference. These images have appeared in numerous books, but the movie was used by the cartoon television show “South Park” to represent hallucinations by the central characters. My physics students thought is was just grand. I have used this thin soap apparatus to show golf ball lift and drag, as well as eddy

Infrared photo of girl with a bubble

Science Photography often takes place outside the light that is visible to the human eye. In this image the light is far infrared. Special cameras lenses are used involving bizarre materials like pure Germanium. The cameras resolution is regulated by the United States Military, but in recent years the standards have been relaxed and now 640x480 are fairly common. The camera only sees heat in a black and white picture. Since the human eye does not see this part of the optical spectrum any color can be assigned to any temperature. In this image blue is assigned to the cooler temperatures, while red is assigned to the hottest areas. Here a young girl blows a bubble with bubblegum. The air inside the bubble as well as the bubble itself cools off quite quickly.