Using Fluorescence Microscopy to Explore the Natural World


There is plenty more to see in a random scoop of sand than one might anticipate. On a trip to the Monterey peninsula (California) the author of the article collected sand from a tide pool at the north end of Asilomar State Beach and then looked at it under a stereo microscope equipped with the NIGHTSEA Stereo Microscope Fluorescence Adapter with Royal Blue excitation. It is incredible how much more there is to see in fluorescence!

Tide pools at north end of Asilomar State Beach

Role of Fluorescence in Marine Biology

The first picture pair below illustrates an area of sand in white light and fluorescence. There is some color disparity in white light, but the scene is a lot richer in fluorescence. There seems to be some emission from mineral grains. The striking red fluorescence comes from chlorophyll, whether small pieces of algae or seaweed growing on mineral surfaces.

Sand from tide pool, white light (c) Charles Mazel.

Sand from tide pool, fluorescence (c) Charles Mazel.

In this following pair, one can observe something in fluorescence that is just about invisible in white light. It is not clear what it is, but definitely the remains of a part of some organism.

Sand from tide pool, white light (c) Charles Mazel

Sand from tide pool, fluorescence (c) Charles Mazel.

Now a larger sand grain displays a striking orange pattern in fluorescence. One can observe some dull brown color in the white-light image. Orange fluorescence is frequently characteristic of phycoerythrin, a photosynthetic accessory pigment that occurs in cyanobacteria and red algae. Higher resolution or carrying out other tests would be required to be sure of what this is.

Sand from tide pool, white light (c) Charles Mazel.

Sand from California tide pool, fluorescence (c) Charles Mazel.

Life in Sand Enhanced by Fluorescence Microscopy

When observing the sand under the microscope, a brightly fluorescing animal kept swimming into the light and settling on the sand, as if wanting to pose for an image. This was an ostracod, a small bivalve crustacean. That is, an animal in the shrimp/crab family that lives inside a hinged shell. When viewed carefully, one can find this in the white light image, but it is striking in fluorescence.

Sand and ostracod from tide pool, white light (c) Charles Mazel.

Sand and ostracod from tide pool, fluorescence (c) Charles Mazel.

Sand and ostracod from tide pool, fluorescence (c) Charles Mazel.

At one point the sand was stirring but nothing could be seen. When the sand was shifted away, it revealed an isopod, another type of crustacean. It was not intensely fluorescent and was also very light- and camera-shy. It burrowed back into the sand almost immediately. Capturing an image of it was pure luck.

Sand and isopod from tide pool, fluorescence (c) Charles Mazel.

Once again, fluorescence has helped reveal a richness and variety of life that can be extremely hard to see in white light.

A day later, sand was collected from the shore from an area about 15 m away from this first sample. This was an area that was wave-swept and wet but not a standing tide pool and in this case there was nearly nothing to see. Only mineral fluorescence and nothing else – no chlorophyll coating the sand grains, and no life moving about. This is a perfect way to study the ecological differences of neighboring environments that experience varying conditions.


This information has been sourced, reviewed and adapted from materials provided by NIGHTSEA.

For more information on this source, please visit NIGHTSEA.

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Last updated: Jan 26, 2018 at 3:58 AM

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