Bony fish make up the largest group of vertebrates, with approximately 25,000 species worldwide. They are characterized by having a bony skeleton, two-chambered heart, scales, lateral line system, and being cold-blooded. Primitive bony fish had heavy scales and fins farther apart on their bodies, and used their air bladders like lungs. There are four main types of scales that provide protection: placoid on sharks, ganoid connected like armor, and cycloid and ctenoid which differ in smooth or spiked edges.

1. Osteichthyes
By Mr. “I like cherry Jelly” Chapman

2. Osteichthyes
• There are approximately 25,000 species of
bony fishes worldwide.
• If all of the living species in all of the other
vertebrate classes were added up, the
sum total would be less than the number
of bony fishes.

3. Fish Characteristics
• All bony fish have:
• Bony skeleton
• 2 chamber heart
• Cold blooded
• scales
• Lateral line

4. Bony Fish
• Primitive bony fishes had/have heavy
scales, their paired fins are far apart on
the body.
• Air bladders functioned as lungs.

5. IS this fish primitive or
advanced?

6. IS this fish primitive or
advanced?

8. Family
tree for
fish

9. Types of Scales
• Scales – thin bony
plates that overlap
each other and
provide protection.
• Glands on the scales
produce a slimy
mucus, which
protects them from
bacteria.

10. Types of Scales
• There are four types
of scales:
• 1. Placoid – type of
scales on sharks
• 2. Ganoid – scales are
connected to each
other (like armor). Ex.
Is a Gar

11. Scales
• 3. Cycloid – have
smooth surfaces and
edges.
• 4. Ctenoid – are like
cycloid scales, but
have sharp/rough
edges that stick out.