What is a fish? What are the major groups (classes and subclasses) of fishes with living, marine representatives?

Question 1

What is a fish?

Answer 1

An aquatic vertebrate with gills and limbs in the shape of fins

Question 2

What are the major groups (classes and subclasses) of fishes with living, marine representatives?

Answer 2

Jawless fishes:
• Hagfishes and lampreys- jawless and cartilaginous- class agnatha
Cartilaginous fishes:
• Jawed and cartilaginous- class Chondrichthyes
o Sub-class Holocephali
 Chimaeras
o Sub-class Elasmobranchii
 Sharks, rays and allies
Bony fishes:
• Ray-finned, Bony fish- class Osteichtyes, subclass Actinopterygii
• Lobe finned, bony fish, class Osteichtyes, subclass Sarcopterygii