When I booted up Creatures 1 again, I found that Echo was on about 60% lifeforce, so she could use a meal. Only problem is, she's too busy kissing Lanque to want to eat, and it looks like he's a little hungry himself. Either that, or he caught on to me telling Echo to 'push food' and went "Hey, I'm food ;)" in an attempt to flirt with the other Banana norn. I'm on to you, Lanque.
Krane had also dipped below 70%, but he was more isolated so he was easier to feed. He's an adventurous norn, and has been to almost every layer of the world: the ground, the trees, and the underground!