The Nature of Things
Pondering the pinniped

Not too long ago I was sitting on one of the more secluded beaches of Point Dume. Off in the distance I could hear the barking of the California sea lion.

A short time later, about 20feet offshore, a large male sea lion swam parallel to the beach. He was quite aware of my presence as well as all other movement on the beach.

After several minutes he turned around and began to swim back. Over the next half hour the sea lion continued his monitoring of the beach, back and forth.

For several days the picture of this mammal stayed in my mind. Although I am also a mammal able to swim, I find myself limited in water. Remarkably though, through the millennia, it seems that the sea lion has adapted keen senses both in and out of the water.

But I wonder . . . Does the sea lion feel as restricted on land as I do in the water?

California sea lions are members of the superfamily or suborder Pinnipedia. Members of this group include walruses, seals and sea lions, species which have their limbs modified as flippers and very short tails. Pinnipeds are semiaquatic, coming on land to give birth and rest.

But all of their food comes from ocean hunting. To aid in this endeavor, pinnipeds have a well-developed sense of hearing and much larger eyes than many other mammals. Their large eye size allows more light to enter, giving better vision in dim waters.

When exposed to bright light, on land or swimming with their head above water, their pupils are greatly reduced.

Another marine adaptation of the eye is the thickening of the lens and cornea. Although aiding in underwater vision, it may result in myopia when on land.

Unlike land-based mammals and more like birds in the air, pinnipeds are less restricted by gravity. Their streamlined bodies and flippers allow them to move gracefully in all directions.

Pinnipeds also have physiological adaptations allowing them to endure extreme underwater elements and sustained time without oxygen.

When diving, the heart beat slows and oxygen ceases circulating throughout the entire body, concentrating in the heart and brain. This allows animals to remain underwater for prolonged periods.

Sea lions also belong to the family Otariidae. Species in this family have small external ears, and their hind flippers can rotate under their bodies, giving more agility on land.

This is used to haul their large bodies onto floating surfaces and/or rocks to rest or sun themselves.

The California sea lion is dark brown or blackish with the females being lighter. The males are much larger than the females, reaching a length of up to 8 feet while the females grow to 6 feet. Males can weigh up to 1,000 pounds, contrasting to the females' 600 pounds. The male also has a much more prominent forehead than the female.

Their distribution is from Baja California to British Columbia, breeding between the Channel Islands and Baja.

Right now Point Dume seems to be an excellent site for observing them swimming as well as resting on several offshore rocks.

Once thought to be a nuisance to the fishing industry, it's now recognized that sea lions primarily eat noncommercial fish, squid, mollusks and crustaceans. They do, however, occasionally damage nets and fishing gear when they become trapped in them.

During breeding season, sea lions congregate in groups to give birth and mate. In early summer a single pup is born, and 10 days to two weeks later mating occurs.

Although fertilization may transpire, sea lions experience delayed implantation so that the young are not born until the female returns to the same breeding grounds approximately a year later, the same time the bulls aggregate.

Although humans are accustomed to spending time in the air and underwater, these worlds are still alien to us. But I wonder if, given enough time, will we, too, adapt to foreign environments with the same fluidity as the sea lion?