Sunday, 16 September 2012 17:45
Students who voted in last week's Cast YOUR Vote chose what habitat we will study this week. The vote was between temperate forests, open ocean, and the intertidal zone. Open ocean won, so here is your Notes From the Trail all about the open ocean.
Over the last few weeks we have started to understand just how large the Atlantic Ocean is. It is amazing to paddle along in the swell and think about the hundreds of miles of water that stretches as far as the eye can see. Oceans cover 71 percent of the Earth's surface. Oceans play an important role in many of the Earth's systems including climate and weather. The oceans support the life of nearly 50 percent of all species on Earth. Marine life has adapted to live in every niche of the oceans, from the poles to the tropics, from estuaries to the deep ocean. The world’s oceans are home to as many as 100 million species – from the largest animal that has ever lived on Earth, the blue whale, to the tiniest bacteria. Oceans contain many different kinds of habitats. Our focus today is on the ocean surface and the ocean floor. You may want to follow some of the links below to learn about all the different layers and habitats in the oceans.
The Ocean Surface
The surface of the ocean, where sunlight reaches, is where most sea life is found. Most of the fish, sharks, rays, jellyfish, marine mammals and sea turtles can be found in this layer of the ocean.
The ocean food chain begins with microscopic drifting plants called phytoplankton. Phytoplankton are found close to the surface of the water where there is plenty of sunlight for photosynthesis. Phytoplankton are eaten by tiny floating animals known as zooplankton. Zooplankton include the larvae of crabs, jellyfish, corals and worms, as well as adult animals like tiny shrimps, copepods and krill.
Moving up the food chain, zooplankton provide food for fish. Big fish eat smaller fish and at the very top of the food chain are large predatory fish like sharks, mammals like seals, and seabirds. Some very large mammals, baleen whales, feed directly on zooplankton. Millions of people all over the world also depend on fish for food.
The Ocean Floor
Seaweed only grows on the ocean floor near coasts, where it gets enough sunlight for photosynthesis. Sponges, sea mats, sea anemones and sea squirts can be found living on the bottom of the ocean. Their food comes from dead plankton, fish, and other detritus that falls to the ocean floor. There are some creatures that crawl along the bottom or burrow beneath it. They are lobsters, crabs, prawns, sea stars, sea slugs and worms. There are also bottom-feeding fish like rays, turbots and halibuts.
Where the ocean is deep, the ocean floor can be in total darkness. Humans rarely have a chance to see the bottom of the ocean. Animals here survive in total darkness and under intense water pressure. Some of these animals have adapted unique traits in order to survive, like glowing in the dark. Most of the deepest parts of the ocean have yet to be explored. Deep ocean submersible machines are used to study the bottom of the ocean – and new life forms are being discovered every year!
This diagram shows all the different layers of the ocean. Image source: http://en.wikipedia.org/wiki/File:Oceanic_divisions.svg
Questions for Discussion
What are some things that you use (and eat) that come from the ocean?
How does pollution affect the oceans?
How does overfishing affect the oceanic food chain?
How do humans fit into the oceans’ food chain?
Further Exploration and Sources
Description of ocean habitat
Layers of the ocean
Investigating ocean impacts
Choosing environmentally friendly seafood
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