Ready to go

My favorite picture from today:

 

Believe it or not, this hydromedusa originated from a hydroid colony that looked like this:

 

When you zoom in, there are tiny medusae (like the one in the first photo) attached to the polyps within this colony.  In the following image, there are several medusae in various stages of development (some younger, some older).  Can you tell which ones are just about ready to swim away from the polyp?

 

On the lower side of the polyp, there are two younger medusae — they look like little ovals with golden spots at the base.  On the upper side, there are two older medusae, one in the foreground and another in the background — their tentacles are now unfurled.  Both of these older individuals appear poised to take off into the wide, wide ocean very soon.

P.S.  To give you some sense of scale, the entire colony in the second photo was only ~2 cm tall.  The hydromedusa is only ~1 mm long.  All of these pictures are greatly magnified.