A marine biologist.
I call them "scientists" but their called oceanographers =D
You call someone that studies metal a metallurgist.
normally .you call one .a letterologist.
Unicelluar.
Probably a bovinologist.
Podologist pod/o- (Foot) -logist (one who studies)
A Paleontologist is one who studies prehistoric life (Fossil's, organisms etc)
Hydrologist
There are many things that could produced the ocean floor. Dying organisms for example are one component in the ocean floor.
diatoms
One who studies the stars is called a(n)... Astrologist
marine organisms