Answer :
Final answer:
Chondrichthyes, like sharks, have true jaws and keel-shaped scales, unlike jawless fish such as lampreys and hagfishes. The jaws allow them to grasp and tear food, while the keel-shaped scales provide hydrodynamic advantages for more efficient swimming.
Explanation:
Differences Between Chondrichthyes and Jawless Fish
Chondrichthyes, such as sharks and rays, differ from jawless fish like lampreys and hagfishes in several ways. One of the most significant differences is that Chondrichthyes possess true jaws with a hin ged structure that allows them to grasp and tear food, whereas jawless fish have a circular-shaped, jawless mouth. Additionally, Chondrichthyes have scales that are shaped like keels, which is beneficial as it provides hydrodynamic advantages, allowing these fish to swim faster and more efficiently in water.
Keel-Shaped Scales and Their Benefits
The keel shape of their scales reduces water resistance during swimming, resulting in more rapid and agile movements. This evolutionary adaptation helps Chondrichthyes to catch prey and evade predators, contributing to their survival as a group over millions of years.
