arthropologist
Coleopterist
If you mean "who studies beetles," then the answer is an entomologist (person who studies insects.)
A scientist who studies insects is an entomologist. An entomologist who specifically studies beetles is a coleopterist.
a person that studies gems is called a gemologist.
The Person Who studies about mamals , he is called mamalogist....
A person who studies animals is called a zoologist.
A person who studies physics is called a physicist, a person who studies chemistry is called a chemist, and a person who studies biology is called a biologist.
A person who studies the mind and behavior is called a psychologist.
A person who studies or writes history is called a historian.
Alligators of reptiles, so one who studies them is called a herpetologist.
A person who studies optometry is called an optometry student or an optometry student.
A person who studies a lot is often called a "bookworm" or a "knowledge enthusiast."