Classification
Three distinct classes of living saltwater fish are Class Agnatha, the jawless fish (lampreys and hagfish); Class Chondrichthyes, the cartilaginous fish (sharks, rays and skates); and Class Osteichthyes, the bony fish.
Fins
The dorsal fin prevents rolling, like a keel on a ship, and aids in turning. The caudal fin propels the fish in the water. The pectoral and pelvic fins stabilize the fish, allow sharp maneuvers, provide vertical movement in the water and serve as brakes. The anal fins contribute to stabilization.
Respiration
Cartilaginous fish have multiple (five or more) gill slits, but bony fish have a single gill opening covered by a bony plate called an operculum that aids the flow of water across the gills.
Reproduction
Bony fish reproduce externally. Sharks and rays reproduce internally and expel the eggs into the water or hatch the eggs internally.
Habitat
Fishermen often categorize saltwater fish as inshore or offshore, depending on their proximity to the shore. However, many saltwater fish move between these environments on a regular basis as part of their life cycles.
Article Written By David Chandler
David Chandler has been a freelance writer since 2006 whose work has appeared in various print and online publications. A former reconnaissance Marine, he is an active hiker, diver, kayaker, sailor and angler. He has traveled extensively and holds a bachelor's degree from the University of South Florida where he was educated in international studies and microbiology.
