One of the marine mammals that you can usually spot during a cruise around the coast of Alaska is the harbor seal. We saw this group off of Aialik Bay in Kenai Fjords National Park. The harbor seal is known as a “sea dog” since it looks like an earless dog when it sticks its head out of the water. Their faces are quite adorable, and some of the ones in this photo look like they are sharing a private joke about the pesky tourists.
The thick coats of the harbor seals tend to be grayish color with black spots or rings. Even though they molt yearly, these markings will remain and are unique to individual seals. Most of the darker colors appear on their backs. This is a defense mechanism so that they blend in with the water when viewed from above.
Harbor seals are excellent divers and have something called a dive reflex. This dive reflex is activated when the seal submerges its head. It automatically causes the seal to hold its breath, slow its heartbeat, and reduce the amount of oxygen being delivered to all organs except the brain and the heart. This dive reflex works so well that the seal is even able to sleep underwater and subconsciously come to the surface for oxygen throughout its slumber. What a trick!