The term fish is used for any any swimming vertebrate with fins. it includes a diverse group of animals, divided into four taxonomic classes, agnatha, chondrichthyes, osteichthyes, and placoderma. taxonomists first divided all "fish" into two classes, agnatha and placoderma. the placoderma are considered ancestors of all other fish. what fossil evidence taxonomists separate all "fish" into these two branches for classification? a) jaw or jawless b) ray fins or lobed fins c) skeleton or no skeleton d) cartilage versus bony skeleton

How do temperature and salinity affect deepwater currents? they create changes in wind direction, moving denser water in the same direction as the wind and causing the deepwater circulation patterns found in the ocean. as temperatures and salinity levels of water increase, the water rises to the surface where it creates currents as it moves to colder regions. they create density differences that cause dense deepwater currents to flow toward the equator where they displace less dense, warmer water above them. they equalize the forces on undersea currents caused by the coriolis effect as they replace more dense water with less dense water.