US naval academy (graduation uniforms)

Factual Questions
1

While perusing the USNA’s website, and specifically the graduation photos for the class of 2007, it seems that while the majority of graduates wear the traditional white uniforms, there is a smaller group of grads who are wearing black. What does this mean? Navy vs marines? Virgins vs deflowereds?

Thanks in advance!

2

Well, in the second picture the collar insignia is pretty clearly that of Marines, while looking at other pics in the site I see the white tunics show no such branch insignia, in the style of the Navy dress white tunic. So probably Navy/Marine.

3

I will not rely on the Edit window and will add this one separately:

In this pic, you can see that the dark tunic is essentially a stripped-down version of the Marine Dress Blue: http://www.usna.edu/PAO/Photos/graduation/gallery.php?entry=Images/Graduation_2007_15.jpg Notice the cinch belt and plain epaulets instead of shoulder-boards.

Compare this one, the white is the Navy Dress White tunic: http://www.usna.edu/PAO/Photos/graduation/gallery.php?entry=Images/Graduation_2007_07.jpg No cinch belt, and shoulder-boards.

Also, on the OPs first (hat-tossing) picture you see the different cut in the jacket vents, and that the male Marines wear a long-sleeve cuffed shirt under theirs, unlike the Navy men.

4

Thanks - much obliged!