Identify characteristics of fishes

Modern fishes include an estimated 31,000 species, by far the most of all clades within the Vertebrata. Fishes were the earliest vertebrates, with jawless species being the earliest forms and jawed species evolving later. They are active feeders, rather than sessile, suspension feeders. The Agnatha (jawless fishes)—the hagfishes and lampreys—have a distinct cranium and complex sense organs including eyes, that distinguish them from the invertebrate chordates, the urochordates and cephalochordates.

What You’ll Learn to Do

• Identify the common characteristics of jawless fishes
• Identify the common characteristics of jawed fishes

Learning Activities

The learning activities for this section include the following:

• Jawless Fishes
• Jawed Fishes
• Self Check: Fishes