University of Florida
University of Florida: Body Features of Sharks
Somewhat shark specific, but a great look at the external anatomy of these cartilaginous fish.
University of Florida
University of Florida: Head Features and Measurements of Sharks
Good diagrams of the external features and labels of the head of a shark, the largest member of the chondrichthyes class.
University of California
Ucmp: Chondrichthyes
Site gives a quick but decent description of the anatomy of the skin and fins.
Middle School Science
Middle School science.com: Perch Dissection
In this lab experiment site, you will observe the external and internal anatomy of a perch, determine the sex of a perch using internal anatomy, and collect statistical data on perch length.
University of Florida
University of Florida: Fin Features and Measurements of Sharks
Some very specific information on the measurements and identifying characteristics of sark fins.
PBS
Nova: The Hunt
Learn more about the six senses that sharks use to hunt. Descriptions and pictures of each sensory organ are provided.