Ichthyology: An Exploration into Fish Diversity

Department: Marine Biology

Instructors: Erica Pandolfi
Instructors' Emails: epandolf@ucsd.edu
Prerequisites: None

Course Description

Fishes are the most diverse group of vertebrates. These gill-breathing aquatic organisms were the first vertebrates to evolve. Due to their long evolutionary history, the adaptations seen in these organisms provide us a glimpse into the pressure that changing landscapes have on evolution. Fishes are found in a wide range of habitats and exhibit a bewildering number of interesting adaptations to suit their niches: from breeding behavior to feeding mechanisms to color-changing abilities, these organisms are fascinatingly complex. This course will introduce you to fish biology beginning with the environment fishes inhabit, and how they adapt to suit those environments. After a brief introduction to fossil fishes, we will delve into the rich biodiversity that exists in modern fishes, through lecture, group-work, hands-on lab activities, and field-trips.

Course Goals / Learning Objectives

The overall goals of this course are to:

  • introduce students to fish diversity
  • appreciate the means through which fishes adapt to suit their challenging environments
  • provide an overview of fish anatomy, ecological environment, and behavior.

By the end of this course, students will be able to:

  • illustrate ideas and principles underlying modern biological classification and its application to living fish groups
  • describe the basic function and organization of fish organ systems
  • describe how variable aquatic environments shape all aspects of the biology of fish species
  • explain how anatomy relates to function across major organ systems in fishes
  • describe major features of existing fish diversity (e.g. number of species, main lineages), its evolution (e.g. timing) geographic distribution and classification
  • recognize basic anatomy; know the reasons for differing structures (evolutionary relationships; specific adaptations)


  • Students will be taking a field-trip to the Birch Aquarium to see first-hand many of the species we will be discussing. They will pick a favorite fish to do a short report on, in which they will detail how that fish’s adaptation to its environment allow it to thrive in its niche
  • Students will be dissecting various fishes to find and identify various physiological structures, and then sort their specimens into their appropriate phylogenetic classifications

Topical Outline

  1. Introduction and background –  What makes a fish, a fish?
  2. Structure and form – brief anatomical and physiological view of the fish
    • Respiration – gills, air sacs, lungs- how do fish breathe?
    • Blood and Circulation
  3. Structure and form 2– brief anatomical and physiological view of the fish
    • Buoyancy and thermoregulation – evolution of the swim bladder
    • Osmotic balance
  4. Feeding and Nutrition
    • Growth – indeterminate growth in fishes
  5. Swimming and Fish Locomotion
  6. Behavior
    • Reproduction
    • Sensory Perception
  7. Systematics and Speciation – how fishes are separated into distinct groups
  8. Evolution of Fishes - the big picture
  9. Jawless Fishes
  10. Chondrichthyes
  11. Primitive bony fishes
  12. Conservation and exploitation


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