How do harbor seals sleep? How long can they hold their breath? The answers to these spine-tingling questions are the subject of today's marine mammal trainer's blog. Let's start with how the seals sleep.

In the photo you see Trumpet sleeping upside down while her hind flippers stick up like rabbit ears. This is not a common sleeping posture, but Trumpet must be on to something since her daughter Cayenne occasionally sleeps "flippers up" too.

Sleeping on the bottom of the exhibit are Reggae, in the foreground, and Cayenne against the wall in the back. Harbor seals can hold their breath for 20 minutes. As the seals sleep deeply, they just bob or roll a little in the wake of other seals swimming by. Alarmed visitors often go to the information desk to report in a whisper, "There is a dead seal in the exhibit. Just thought you should know." While the visitor is conscientiously reporting their findings to the staff, the sleeping seal rises to the surface for a couple of quick breaths before sinking slowly back to the bottom. This cycle can repeat itself for hours.