I think "striker is a pretty general term for a person who's going after a rating like "Petty Officer".
I stole the following from answers.com:
Enlisted members of pay grades E-4 and above are said to be "rated," meaning that they possess a rating, or occupational specialty. Members of grades E-1 to E-3 can become "strikers," meaning they have rating designations like Petty Officer (example: a BM3 is a Petty Officer Third Class rated as a Boatswain's Mate; BMSN is a Seaman designated as a Boatswain's Mate striker), but do not necessarily have to be. Whether a designated striker or not, personnel in the pay grades of E-3 and below are all considered "Non-Rates." There are more than 50 ratings covering a broad range of skills and subspecialties.
For example, SA SMITH, MARY. would be considered a Seaman Apprentice. Prior to her rank of SA a rating would be placed. Therefore, her entire title would be ITSA SMITH, MARY. IT indicating Information Systems Technician. As for ENFN THOMPSON, JOHN. EN specifying the occupation as Engineman and FN as Fireman.