The Fish
Vertebral column: bony or cartilaginous spine surrounding dorsal nerve cord; skull encasing the brain (ex. Agnatha)
Jaws and paired appendages (pectoral fins, pelvic fins)
Closed, single-loop blood system with a heart
Nutritional deficiencies: unable to synthesize aromatic amino acids (must be provided with food/prey); has been inherited by all higher vertebrates
Two major groups:
- Class Chondrichytes: sharks, skates and rays
- Class Actinopterygii = Osteichthyes = teleosts = bony fish