Chondrichthyes
Osteichthyes

CHARACTERISTICS OF A FISH

Fish is an animal that swims in the water most of the time. They have scales and gills  All fishes have a heart and are shaped differently They are all water dwelling vertebrates

They are divided into three classes osteichthyes ( bone) ,Chondricthyes ( Cartilage ) and Agnatha ( Jawless)

Osteichthyes ( Bony fish) have these in common :

EXAMPLE : Giant Sea Bass

1. They have one-three gill openings
2. Fishes can have teeth on their tongue, throat and in  the front of their mouth
3. They have Scales that grow as the fish grows.
4.  Bony fishes have fins that are supported by bony spines or rays

Condricthyes ( Cartilage) have these in common :

EXAMPLE : Sharks

1.  They have 5-7 gill openings
2.  They have teeth that are only in rows at the front of their mouth.
3.  They have dermal denticles are shed and replaced by larger denticles.
4.  They have fleshy fins

Agnatha ( Jawless) :

EXAMPLE : Lampreys

1. there are no jaws