Marino and colleague Diana Reiss at Columbia University in New York studied two teenage dolphins. They put a Mirror in a small round pool that was connected to a larger oval pool by an open gateway. The mirror was positioned just inside the gateway so it could not be seen from the larger pool. The dolphins were called to the side of the larger pool and either marked with a non-toxic magic marker or rubbed in the same way with an inkless pen. The marks were made on the dolphin’s heads, fins, and bellies so they could not see them without looking in the mirror. We found that not only would they make a beeline for the mirror and spend time looking at themselves but they would posture in front of it to expose the marked part of the body to the mirror. If the inkless pen was used the dolphins would check in the mirror for marks but move on if they could not see any.