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MARINE LIFE
Lying at the edge of the sea and harboring, many complex communities are the tidepools. These miniature arenas teem with organisms whose very existence in this surf-pounded realm is proof of their hardiness. Here, desperate struggles for survival are an everyday fact of life.
The battle begins from the moment they attempt to gain a foothold on the rocks. Crashing waves and powerful currents, as well as the suffocating heat of the sun during low tides, are but a few of the elements they must contend with, and competition for space is intense. Only the fit and the fortunate endure - if they escape the attention of the predatory tidepools inhabitants, which in turn are vulnerable to legions of other voracious predators. Life in the endless food web can be precarious.
The sandy beaches seem almost desertlike, but like deserts they do host a number of unseen inhabitants. Perhaps the most familiar of the beach denizens is the sand crab, a creature about the size of a marble. Farther up the shore the sandhoppers lie hidden in the sand searching for kelp fronds and other edibles. In the regions of calmer seas numerous shells pebble the sand in and beyond the surf. Sand dollars live offshore in shallow sand. Their delicate shells are sometimes found washed up on the beach.
At the bottom of the shore, plants and animals are larger, there are more species, and they must cope with different problems. Many species, such as large barnacles and sea-squirts, are sessil - they are stuck to the rocks and cannot move. Others, such as fleshy, branching seaweed's, sponges, and sea-anemones, are soft bellied. Rarely do these plants and animals need to survive prolonged periods of drying out. These plants and animals can grow quickly and large due to the lack of physiological stress.
Some 20 species of whales, dolphins, and porpoises are exclusive to the Pacific. They do, however, share the ocean with some of the other more widely distributed species. All creatures but one are toothed and actively pursue their food. it is a mixed group consisting of five species of beaked whales, 11 dolphins and two of porpoises.
In the Southern Hemisphere, seals are generally regarded as inhabiting the Southern and Antarctic oceans. Nevertheless the leopard seal occasionally appears along the east Australian coast and fur seals are a common sight on the shores of New Zealand and South America. The north Pacific, however, harbors quite a variety, the best known of which is the California sea lion, an eared seal that has made a name for itself as a performing seal.
Another Pacific mammal is the sea-otter, which occurs in the colder waters of the American shores of the north Pacific. Sea otters have the remarkable habit of fetching a flattened stone from the depth, and while floating on their back at the surface, placing the stone on their chest. They then proceed to open such food as sea-urchins, mollusks, and crabs by cracking them against the stone.
All seabirds are carnivores, with the majority taking fish, squid, or krill. To find their prey, seabirds must be particularly sensitive to water temperatures and currents. Some species favor warm waters, others cool. Often, productivity is greatest where waters of different temperature meet, particularly where cold, nutrient-rich water wells to the surface at the edges of continental shelves or in eddies, rip-tides, and other turbulence.
Seabirds have adapted to their marine environment in different ways, though they have in common webbed feet for swimming and salt glands for removing excess salt from their blood. Most seabirds have a waterproof plumage, but their close relatives, the frigatebirds, have apparently sacrificed this capacity to save weight and energy. As a result they can stay airborne for weeks at a time, snatching food from the ocean's surface or stealing it from other seabirds.
More than 300 marine and estuarine sites around the world have been reserved as protected areas for their outstanding features. Initially, areas were set aside to protect the beauty of their marine features for tourists. Now areas have been established to protect the feeding, and breeding habitats of much of the worlds marine life.
The Channel Islands National Marine Sanctuary off southern California, established in 1980, is the largest marine protected area in the United States. Many of the world's whale species, such as California gray, humpback, blue, fin, and sei whales, regularly migrate through it.
Major challenges lie in store for the protected marine areas such as, exploding tourism, damage to reefs by crown-of-thorns starfish and other species, and excess nitrogen, phosphorus, and sediments from land-based activities, and the decline of commercial and recreational fisheries.
The survival of healthy oceans to provide a wealth of natural resources now and in the future will depend on extensive protection and integrated management of the marine environment through the reservation of significant or representative coastal and offshore areas. All lovers and users of the sea have a responsibility to promote the protection of our rich marine heritage by encouraging cooperation at all levels of government and within our own communities.
Screen Saver Photography provided by Frank Balthis
