Yes. It's not part of the word count, but you do include a "References Used in Preparing this Manuscript" section at the end of your submission (or Bibliography, References, or however you'd like to word it) to show you have done your research. They need to be reliable websites (e.g. museums, government agencies).
Wikipedia can be useful to put you on the trail of some reliable sources (cited at the bottom of each wiki article), but should not be listed in your submission.
Good luck with your submission! (I love sharks.)