Copyright a 3D animation

Well, the copyright is a right you own if you are the author of your project. If you need to prouve it, send it to a copyright office in your country (there are different rules in each country, but basically you should send a CD or a DVD where you put your files). Also if you are planning to publish your stuff worldwide, it is a good idea to register your copyright in the US Library of Congress (sending it to Washington with $45 fee) since US laws in communication are respected everywhere.

You hold copyright by default on everything you create, especially with a 3D project you'll most likely keep the project files as well along with some form of signature in it and that's enough by law.