When I made the jellyfish for the
Supercute Sea Creatures, I used a single line of blanket stitch along the bottom edge.
My
blanket stitch tutorial only showed how to do blanket stitch if you were going all the way around. I added a little section to the tutorial that shows you how to start a blanket stitch if you don't intend on meeting back up with the first stitch so you can keep your first stitch vertical.
That tutorial page is WAY long. It's such a monster. I need to rethink that page and get it looking more usable. Maybe I should split all the little bits up and put them on their own pages. Hmmm.