Why don't turtles eat frogs?

I have this two baby turtle, they are so cute and this expensive Beautiful rare beta yellow cost me $11.00 it had a flowing yellow fin soooo beautiful and 4 small shrimps 25 cent and two small frogs with plants, it was about two weeks. I turn to look at the Beautiful flowing yellow fin beta and there in horror was only the Beautiful yellow fin flowing, with no body! The turtles or monster eat the beta a week later I couldn't see the shrimp not one. The turtle had to have eaten them all left is the frogs, two small frogs, that been in there for months. Why didn't the turtles eat them the monsters. The turtle touch and swim next to them. I just want to know why don't they eat the frogs they ate about everything else. p.s. I knew turtle eat fish, but they were baby turtle, babies! THX