In the 15w31a snapshot, it's possible to use ender pearls in Creative mode. But instead of just staying in the inventory, they disappear for a little moment upon being used. For example, if you have one, it will disappear and appear again; if you have 10, they will get 9 for a moment and then come back to 10.

Probably the code for throwing ender pearls in Creative is the same as Survival: it takes the ender pearls from you after you threw them. But then the game realizes you shouldn't have lost the ender pearl and gives it back.

ADDITION: After you throw it, even the item tooltip appears on top of the hotbar, as if the item was being given to you through /give.

Steps to reproduce:
1- Get some ender pearls and make sure you're in Creative mode.
2- Throw some of them.
3- Look closely on your hotbar. You'll be able to see that it disappears for a little moment, as if it was being consumed.