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Thursday, January 22, 2009
Next week we will explore the diversity of forms in the fish world. The more you study fishes you will see that some fish look so strange to us that it's hard to believe they're real. As you read Chapter 2 on Form and Movement, keep in mind the fundamental premise that all species persist because what they look like and what they do help them to survive, avoid getting eaten before they can attract mates. So what you see when you observe a fish is a unique set of traits that are part of a whole strategy to maximize fitness of individuals in a particular place and time. The photo at the right is a Handfish (Brachionichthys hirsutus).
We study anatomy because it is fundamental to how we classify and name fishes. However, if you remember that form relates to function it will be easier to apply your knowledge of anatomy to new fishes that you encounter. Our current classification system for fishes (from Nelson's Fishes of the World, Fourth Edition 2006) uses many character traits and numerous studies. Louis Agassiz (1807-1873) first classified fishes based on scale type alone: Placodermi had placoid scales, Ganoidei had ganoid scales, Cycloidei had cycloid scales, and Ctenoidei had ctenoid scales. Today we recognize groups of Chondrichthyes (placoid) and Osteichthyes, which contain Chondrostei and Holostei (ganoid scales), and Teleostei (cycloid and ctenoid scales).
Louis Agassiz would evaluate a student's potential for science by placing the student alone in a room with a single fish for a day and periodically pop in to quiz the student about what he had learned. The stories from the paleontologist Nathanael Shaler and Samuel Scudder illustrate this premise that "you can learn a great deal about a fish from its exterior traits."
Read Chapter 2 to learn more. Or if you prefer I will leave you alone in the lab for a week with a single fish. Click on the Comment button below and share with us your thoughts about the unique adaptations of the fish that you would be if you could be a fish. What do the exterior traits of this fish tell you about its habits or habitats?
Tuesday, January 20, 2009
If you are viewing this blog then you are most likely a student newly enrolled in my class, Stream Habitat ManagementIchthyology. You have reviewed the syllabus, assignments, and read the first few book chapters, and started dissecting the lamprey.
This blog is a place for all students to come together and share their perspectives on learning all about the fishes. Every day many news stories on the plight of our fishes and the conflicts that arise as humans use fish in unsustainable or inappropriate ways, often with little understanding of the complexity. We can learn better by sharing our knowledge and expertise in and out of class.
Some days I may just post a photograph that is meaningful to the topics we are exploring. This image is part of a project to digitize early volumes of the Chicago Field Museum. This emphasizes the lasting importance of quality scientific illustration.
Other days I may post questions and issues via the blog and expect that you will respond to these questions based on your reading the assignments and studies. At other times I will point you to interesting stories.
In the spirit of "Students Quizzing Students" I hope that you will use this blog to post questions about the topics we are studying.