Microscopy Primer
Light and Color
Microscope Basics
Special Techniques
Digital Imaging
Confocal Microscopy
Live-Cell Imaging
Photomicrography
Microscopy Museum
Virtual Microscopy
Fluorescence
Web Resources
License Info
Image Use
Custom Photos
Partners
Site Info
Contact Us
Publications
Home

The Galleries:

Photo Gallery
Silicon Zoo
Pharmaceuticals
Chip Shots
Phytochemicals
DNA Gallery
Microscapes
Vitamins
Amino Acids
Birthstones
Religion Collection
Pesticides
BeerShots
Cocktail Collection
Screen Savers
Win Wallpaper
Mac Wallpaper
Movie Gallery

Polarized Light Microscopy Digital Image Gallery

Ctenoid Fish Scale

Scales, which are formed directly in the skin membrane of fish, act as an external form of protection from predators and other dangers in the environment. The number of rows of scales a fish possesses as well as the scale type are characteristics considered in species identification.

Fish scales are typically divided into four main groups, one of which is comprised of ctenoid and cycloid scales. Both of these types of scales are similar in composition, consisting of a rigid surface layer primarily made of crystallized calcium-based salts and a deeper, fibrous layer predominantly composed of collagen. They differ, however, in shape. Cycloid scales feature a smooth posterior edge, but ctenoid scales display ctenii, bony, comb-like structures that decorate the outer margin of the scale. Ctenii may exhibit a wide range of morphologies that vary by species.

Ctenoid scales, which are commonly found in the majority of bony fishes, can sometimes be utilized to estimate the age of the creature to whom they belong. This interesting exploit is possible because when a fish grows, concentric "growth rings" similar to those of trees are formed on its scales. These rings, called circuli, appear closer together when the weather becomes cool and growth slows down, leaving dark bands known as annuli. By counting the annuli, scientists can roughly determine how many winters or cool periods the fish has undergone, resulting in an approximation of its age.


BACK TO THE MISCELLANEOUS POLARIZED LIGHT GALLERY

BACK TO THE POLARIZED LIGHT GALLERY

Questions or comments? Send us an email.
© 1998-2013 by Michael W. Davidson and The Florida State University. All Rights Reserved. No images, graphics, 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: Tuesday, Jul 25, 2006 at 09:54 AM
Access Count Since November 20, 2003: 15813
For more information on microscope manufacturers,
use the buttons below to navigate to their websites: