Determining which tables are available (oracle)

I am trying to connect to an oracle database using the OCI8 tools and
everything appears to be working fine (rake db:migrate pulls no
errors). The only issue is, I'm not sure how to determine which tables
are available. I know the table names for running queries, but they do
not appear in the localhost.

e.g. select * from [tablename] would return results in Oracle, but
http://localhost:3000/[tablename] can not be found. Is there a way to
determine how to properly display the table names?

If I am trying to reference a table that already exists in my
database.yml file, will rake db:migrate pull in the data that is
already there?