Lucernal Box Camera Microscope (circa mid 1700s)

License Info
Image Use
Custom Photos
Site Info
Contact Us

The Galleries:

Photo Gallery
Silicon Zoo
Chip Shots
DNA Gallery
Amino Acids
Religion Collection
Cocktail Collection
Screen Savers
Win Wallpaper
Mac Wallpaper
Movie Gallery

Wim van Egmond

Coscinodiscus Diatoms

Described by German scientist Christian Ehrenberg in 1838 based on fossil specimens, Coscinodiscus is a genus of centric diatoms present in most bodies of water. Especially abundant in coastal areas, the free-living organisms are an important food source for microcrustaceans and a variety of other aquatic life forms.

Coscinodiscus Diatoms

Taxonomically, diatoms are generally placed in either the algal phylum Bacillariophyta or in the class Bacillariophyceae of the protist phylum Chrysophyta. Tens of thousands of the chlorophyll-containing organisms have been identified in the fossil record, but only about 5,600 species are extant. The great abundance of diatom fossils is primarily due to the siliceous cell walls known as frustules that house them. Extremely durable, the frustules often display complex and intricate markings, a characteristic that has made them extremely popular with microscopists. In fact, the beautiful, symmetrical designs are sometimes even used to test the resolving power of microscopes.

Many diatoms are planktonic, but some species attach to substrates, such as plants or rocks, while others are bottom dwellers. The organisms range in size from approximately 2 micrometers to several millimeters, though only a few exhibit diameters greater than 200 micrometers. Typically, diatoms are divided into two basic categories: the radially symmetric Centrales, such as Coscinodiscus, and elongate, bilaterally symmetric Pennales. In addition to their disparity in shape and symmetry, the two orders of diatoms may differ in their ability to locomote. Often Centrales are considered to be nonmotile, while Pennales may move through aquatic environments with a gliding motion facilitated by mucilage secretions.


Questions or comments? Send us an email.
Photomicrographs are © 2000-2022 by Wim van Egmond.
All Rights Reserved under copyright law.
© 1995-2022 by Michael W. Davidson and The Florida State University. All Rights Reserved. No images, graphics, software, scripts, or applets may be reproduced or used in any manner without permission from the copyright holders. Use of this website means you agree to all of the Legal Terms and Conditions set forth by the owners.
This website is maintained by our
Graphics & Web Programming Team
in collaboration with Optical Microscopy at the
National High Magnetic Field Laboratory.
Last modification: Friday, Nov 13, 2015 at 02:18 PM
Access Count Since September 15, 2003: 23413
Microscopes provided by:
Visit the Nikon website. Visit the Olympus Microscopy Resource Center website.