Seals and sea lions, continued

This is not quite a sea lion, but a very close relative!

Adaptations to the aquatic environment:

o Sea lions swim with an up and down motion, using wing like strokes of their foreflippers.

o They are very agile and maneuver very well in the water.

o They are probably capable of swimming up to nearly 14 mph, but generally cruise at speeds of around 2 mph.

o I have witnessed sea lions in nature, where they will leap out of the water on an incoming wave and land upright onto a rocky shoreline that is being washed over by a wave. At times, that leap is equal to about a 5 foot jump out of the water.

o They usually do not dive very deep, since most of their food is found in shallow waters less than 200 feet deep. They can be experimentally induced to dive to at least 900 feet deep, however.

o They can stay submerged for around 3 minutes; however, they can remain under water for up to about 10 minutes, if necessary.

o When diving, as with all marine mammals, their heart rate slows down dramatically during a dive, from about 95 beats per minute above water to less than 20 beats per minute while diving. This allows the animal to conserve oxygen.

o Sea lions have a higher blood volume than nondiving mammals of comparable size. This increased volume allows greater oxygen-binding capacity. When diving, the blood is shunted away from tissues tolerant of low oxygen levels to the heart and central nervous system organs.

o The muscles of the sea lion, as with all marine mammals, have a high content of the oxygen binding myoglobin (storage of oxygen) to help prevent muscle oxygen deficiency.

o Like most marine mammals, a typical respiration cycle is a short exhalation, a short inhalation, and a longer breath holding period. Each exhalation and inhalation lasts about a second. The breath holding period can last from 12 seconds to over 15 minutes.

o On land, California sea lions exhibit a variety of sleeping postures. They commonly sleep on the beach with all 4 flippers tucked under the body or with the foreflippers tucked under but the hind flippers together and extended. They also commonly rest and sleep balanced upright with their heads thrown back, noses pointed upward.