THE PELAGIC ZONE: THE LIVING DESERT
The Pelagic zone is by far the largest of the aquatic biome, and is sometimes referred to as a desert, due to its lack of land masses above the surface. This is the open waters of the sea, and where most life is abundant. A lot of fish we eat comes from this zone, such as mackerel, sardines, and tuna. Due to over fishing, many species like sharks face extinction.
Pelagic life exists in 3 categories:
Photosynthetic organisms are dominated with these microscopic organisms, which form the food base for all marine animals. Diatoms, zooplankton, and dioflagellates all have features which allow them to float near surface waters.
Zooplankton- These are one celled organisms, such as small jellyfish, as well as microscopic and small free swimming animals, such as smaller crabs, or squid.
Neckton- Animals that swim freely about the ocean; such as bony fishes, cartilaginous fishes, sharks, whales, dolphins, seals, turtles, snakes, arthropods, such as crabs and lobsters, and molluscan animals, such as squid and octopuses.
Many sea animals use coloration as a defense mechanism; having a light underbelly side, and a darker back, so they are harder to see from above, and blend with the depth of the water.
Next time, we’ll take a look at the Photic zone, where darkness takes hold, and animals can no longer use natural light. Until then, may your sea travels be safe ones.
THE ESSENCE OF LIFE
Ever wonder what it would the world would be like without water? Well, for one thing, we wouldn’t be here. Water is essential for life, and covers 70% of the planet. 97% of the world’s water is contained in its five oceans, and fresh waters such as glacier; rivers, lakes, and streams cover only 3 %.
Most scientists are in agreement that the Earth’s oceans gradually formed, as a result of the release of volcanic gases and water vapor into the atmosphere from its interior core. The panspermia theory is also widely accepted in the science community, but most agree it was a combination of both.
The oceans are essential for all life, and forms a part of the carbon cycle, and influences climate and weather systems. The total mass of the hydrosphere is 1.4 quintillion tons, or about .023% of the Earth’s total mass, and 139.7 million square miles in area. It was formed roughly 3,800 million years ago. The deepest point is in the Mariana Trench at 6.831 miles, and the seas still remain one of the most unexplored regions of our planet. Disolved organic material and chlorphyll give the ocean its bluish color. The bioluminescence of sea creatures sometimes gives it a glow at night.
The ocean is divided into zones:
Pelagic Zone-This is of the zone above 200 meters, and most sunlight shines into this region. Most surface dwelling aquatic animals and fish live in this level.
Photic Zone-The region where photosynthesis occurs, and where most life thrives. Any life forms below this level must rely on sinking material, or find another food source, such as life near hydrothermal vents.
Hadopelagic-This is the deepest part of the ocean, where creatures create their own light source, and become bioluminescent. Anything that lives on this level must withstand pressures 1000 times greater than the surface. Temperatures this deep can reach as low as 34° F.
Wind and wave currents are guided by the tectonic plates, the lunar tides, and atmospheric conditions. Due to the rotation of the Earth, Northern and Southern hemispheres guide the direction of the currents in opposite patterns.
The Mariana Trench is 2,550 miles long, 43 miles wide, and 36, 201 feet deep, almost as tall as Mt. Everest. The Alvin was the first and only vehicle to reach the bottom of the oceans. Between 1964-1999, it made 3,535 dives, and carried over 10, 540 people, three at a time.
Next time, we’ll look at some the diverse aquatic life found at every level. Until, then, enjoy your day at the beach!