April 19, 2011

Algae structures and shapes

For five weeks now, I have been participating in a course about freshwater phytoplankton by the expert A.M.T. Joosten. He is famous for his knowledge about desmids and cyanobacteria. The most amazing thing that I discovered during the course, is the variety and complexity of phytoplankton. They have very different shapes and features.

Algae even seem to be flat when you look at them on photographs. Actually, most algae are not flat at all! I created two movie files taken from image stacks to show shapes. Image stacks work as a kind of MRI-scan: you take photographs as 'slices' and you can scroll through these slices, revealing the 3D character of the algae - without modelling it into a 3D model. The Bambusina brebissonnii below has cells which are shaped like little tubes with two ridges, forming a longer tube in total.

Yet, another shape of the Eremosphaera viridis reveals that algae can also take shape as a sphere. The species can vary in a range of 50-180 μm in diameter. You can clearly see the lens-shaped chloroplasts creating the spherical structure. I only took a stack of about 1/4th of the sphere, shown in the video below.

Other species of algae are fusiform, truncate, conical, curved, covered with thorns or ridges, and many other shapes too hard to imagine... untill you explore the field of phytoplankton.

Image stacks © GWL
Videos by: Marta Demarteau
Mastered by: Gerald L. Fitton

All videos taken by Nikon Inverted Microscope Eclipse Ti-U (100w), Nikon DS-Fi1 camera, NIS Elements BR 3.22.00.