|Fish is a class of organisms that fall under vertebrates. Fish are vertebrate animals that live in water, have streamlined (ability to flow in water), muscular bodies, and are cold-blooded.
They have gills that help them breathe and fins that help them swim in water.
There are basically three types of fish:
Jawless Fish or Agnatha: These have no fins, no jaws and a skeleton without bone.
Chondrichthyes or Cartilaginous Fish: These do not have bones, have paired fins and no swim bladder (this provides buoyancy, i.e., the ability to swim). Their skin has tooth-like scales called denticles.
Osteichyes or Bony Fish: Osteo means bone; these fish have a skeleton made of bone and paired fins. They also have teeth that are fixed onto the upper jaw. They have a swim bladder.
Directions: Answer the following questions.