Regurgitating vital organs

Most species of frog can regurgitate their stomach. This mechanism is in place so that they can expell undigestable food (their digestive tract doesn't go straight through, it ends at their stomach). I'm not positive on this, but I don't think this is a reaction to being put into alcohol (or whatever preservative; formaldahyde isn't used anymore, it can cause cancer or something). Most likely, the biological supply company threw some of those frogs in so the teacher could show what this process looks like.

The sea cucumber is possibly the most.. advanced member of the echinoderm family, which also includes the starfish and a few other animals. The one main defining characteristic of this family is the ability to regenerate practically anything that's lost; i.e. you cut an arm and a chunk of the center off the starfish, and the starfish grows a new arm, and the arm grows a new starfish.

Well, this nifty genetic ability lets the Sea Cucumber do something that as far as i'm aware is totally unique.

Sea cucumbers can at any arbitrary moment expunge all their internal organs as a defense mechanism

Yup. Startle a Sea Cucumber and its reaction is to spew out all of its internal organs at whatever appears to be startling it. I guess this is in order to give it time to get away, or whatever. Sounds like a rather stupid ability, but i guess it must be effective, because the species seems to be surviving rather well.