A Botanist is a person who studies plants but also studies waterfalls.
A scientist that studies bats is called a chiropterologist.
A scientist who studies mollusks is called a teuthologist.
The name of a scientist that studies sports is called a sports scientist.
A scientist is someone who studies science.
A scientist who studies butterflies and moths is called a lepidopterist.
An Entemologist
A scientist who studies animals is called a zoologist.
A scientist that studies fungi is called a mycologist.
A scientist who studies insects is called an "entomologist".
A scientist that studies viruses is called a virologist.
A scientist who studies radioactivity is called a nuclear physicist or a radiologist.
They are called geologists.