Continental Shelf & Continental Slope

A continental shelf is the flat or gently sloping land that lies underwater around the edges of continents. It extends from the shoreline out to where the ocean floor begins to drop drastically. It is an important zone in both separating ocean life zones as well as providing income for shoreline economies. The continental slope begins at the drop off ending the continental shelf, and slopes down more drastically to the ocean floor. As currents bring water towards shore, and the water comes up the continental slope and then hits the continental shelf, nutrients are brought upward (upwelling) to make the continental shelf a place where ecosystems thrive.

Currents

There are two main types of currents. The first is a surface current. Surface currents are caused by strong winds blowing over the ocean. The second type of current is a deep current. Deep currents are driven by differences in water density. Seawater becomes denser when it is colder or has a higher salt content than surrounding water. Aside from the basic surface and deep currents, there are two more specific currents we need to focus on, upwelling and downwelling. These specifically affect the nutrient and oxygen flow within the ocean’s ecosystems. As all currents move, they impact the temperatures of the entire planet!

Upwelling

Upwelling is the movement of water up to the surface. This process brings up nutrients from the deep oceans. This means that many ocean animals live where upwelling occurs. Many fisheries are located in areas of upwelling because of the thriving life. Upwelling and downwelling are important processes that describe mass movements of the ocean water, and both affect ocean temperature and currents because of their movement.

Algae

Algae are a diverse group of plant like organisms. They are the most important photosynthesizing organisms on earth and come in a wide variety of sizes, forms and have differing characteristics - some even lack roots and leaves like most other plants have. Algae are the foundation of aquatic food webs and have many economic benefits.

Downwelling

Downwelling is the movement of water from the surface to greater depths. As the water sinks from the surface due to density, it carries with it the oxygen that animals need to live down deep. Animals in the ocean need the same oxygen we do in order to breathe! The relationship between upwelling and downwelling is essential to stirring the ocean – they distribute oxygen to the deep (downwelling), nutrients to the surface (upwelling), and both actions affect ocean temperature and currents.

Gases

The behavior of gases in the ocean is extremely important to maintain balance between the ocean and atmosphere, as well as life within the ocean. The most important gases in the ocean are oxygen, carbon dioxide & nitrogen. Plants and animals within the ocean need oxygen for respiration (breathing). Carbon dioxide is combined with sunlight to perform photosynthesis, and as a portion of it forms bicarbonates, it is also used by many animals to form their shells. Nitrogen allows most sea creatures to make proteins that are essential for life.

Hydrothermal Vents

Hydrothermal vents are openings in the Earth’s crust that are created when cold ocean water seeps into cracks on the ocean floor and is heated deep underground by hot magma. They are usually located near areas of different types of plate movement. They are geysers on the seafloor where super-hot, mineral rich water continuously gushes out. Because of the nutrients coming out of them they support very interesting ecosystems in which the organisms perform a process called chemosynthesis rather than photosynthesis to survive.

Salt

The ocean contains many nutrients and minerals vital to life. One of the most abundant and the most important is salt. The elements that make the salt found in oceans come from rocks and minerals that rain and rivers wash into the ocean over time. Salt can also come from below as one of the minerals coming up from hydrothermal vents or underwater volcanic eruptions. Salinity is a measure of the amount of dissolved salt in a body of water. The salinity in the ocean can vary in different locations due to evaporation or other conditions.

Bioluminescence

Bioluminescence is the production of light by a living organism. It is a chemical reaction that cause light energy. Three components are needed for a bioluminescent chemical reaction: oxygen, the molecule luciferin, and the enzyme luciferase. The animal’s specifc chemistry can cause bioluminescence in different colors. Bioluminescence is used to confuse predators, attract mates, lure prey and signal or communicate.

Chemosynthesis

Most life on Earth is dependent upon photosynthesis, the process by which plants make energy from sunlight. However, several unique ecosystems have evolved in the absence of sunlight, and its source of energy is completely different: chemosynthesis. Chemosynthesis is the process by which certain microbes (usually bacteria) create energy for organisms by using chemical reactions. The animals that live around hydrothermal vents, underwater volcanoes, and methane cold seeps all make their living from the chemicals coming out of the seafloor! All of these ecosystems are very highly populated compared to other areas in the deep ocean or on the ocean floor due to the process of chemosynthesis.

Ocean Life Zones

The 3 zones of the ocean moving from the shore outwards are the intertidal zone, neritic zone and oceanic zone. There are other zones that are categorized by the depth of the water, as well as the amount of sunlight they receive, which you will see at other stations. Each different zone has a variety of life forms and ecosystems that interact with each other that are important to keep the planet in balance. Do you remember examples of the ecosystems that are in each life zone?

Underwater Volcanoes

The magma and lava create the edges of new oceanic plates and supply heat and chemicals to some of the Earth's most unusual and rare ecosystems. Underwater volcanoes bring three things into the deep ocean that otherwise wouldn't be there: hot water, minerals and bacteria. The bacteria in marine volcano ecosystems do more than provide food for small organisms. They also provide a means of obtaining nutrients for many of the larger species in a symbiotic relationship. In fact, giant tube worms have no digestive systems at all. Instead they allow massive colonies of bacteria to live within them. These bacteria then synthesize nutrients for them. Scientists are busy trying to gather more information about the adaptations of marine life that live near these volcanoes, as well as their proposed effect on global warming.

Temperature & Thermocline

The ocean’s temperature varies greatly mostly due to 2 factors: latitude (or distance from the equator) and water depth. The temperature affects many things from the type of life forms to the nutrients in the water.

The thermocline is a transitional layer that separates the warmer surface water from the colder deep water. The temperature within this layer decreases rapidly.

Methane Cold Seeps

The discovery of hydrothermal vents and cold seeps shows that life can also exist

independently of the sun. The unique communities here derive their energy from chemicals rather than sunlight. Chemicals at these cold seeps literally seep from the Earth’s crusts, but at the same temperature as the surrounding seawater.

Since the discovery of hydrothermal vent ecosystems dependent on hydrogen sulfide, scientists have found similar communities living around these so-called ‘cold seeps’. Others have also been found that rely on methane instead of hydrogen sulfide. Some of these are around bizarre deep-sea lakes called 'brine pools': depressions in the sea floor filled with water that has a much higher concentration of salt then the surrounding water. And recently a tube worm community was found living on solid methane seep on the ocean floor.

Apart from temperature and the chemical used for energy, another major difference between vent and cold seep ecosystems is the rate of growth. Vent creatures generally grow fast - giant vent tube worms are one of the fastest-growing animals on Earth, however; they only live for a few decades. Organisms at cold seeps grow much more slowly, but seep tube worms are thought to live for up to 250 years.

The deepest cold seep ecosystem discovered so far is located in the Sea of Japan at a depth of 5,000 to 6,500m. Other cold seeps and ‘chemosynthetic biological communities’ have been found in the Gulf of Mexico, the Monterey Canyon off the coast of California, US, and off the coast of Alaska, US.

Deep Ocean EcosystemThe deep ocean begins where the sunlight fades, at 656 feet, and extends to where no light penetrates. The water contains little oxygen, and the temperature is just above freezing. Pressures reach up to 1,000 times greater than the pressure at the surface. Ocean researchers estimate 100 million species exist in the deep ocean -- more biological diversity than all terrestrial ecosystems combined...yet we have known little to nothing about them or their mere existence until recently. One study of a deep-sea community revealed 898 species from more than 100 taxonomic families and a dozen phyla in an area about half the size of a tennis court. More than half of these were new to science. Although these days everyone is obsessed with zombies and aliens, some of the strangest and most terrifying creatures in the universe lie in the pitch black depths of the ocean.

Primarily found in the deep water off of Australia and New Zealand the Blob Fsh lives at depths of over 1200 meters. The pressure here is several dozen times higher than at the surface and as a result its body is little more than a gelatinous mass.

Termed a living fossil, this seldom seen Frilled Shark inhabits the depths of the Atlantic and Pacific Oceans. Scientists speculate that it captures its prey by bending its body and lunging forward like a snake while proceeding to swallow its victim whole.

The Angler Fish is an incredible example of how living organisms can find a way to survive in even the most inhospitable environment. The Angler Fish lives more than a mile deep in ocean water. There are over 200 species of anglers, which are named for their method of 'fishing' for their food.

A spine of the dorsal fin acts as a 'fishing rod', tipped with a fleshy 'bait' which is often luminous.

Other fishes are attracted to this lure and get eaten. The males are very small in comparison with the females, and live as permanent parasites

on the female. The male attaches himself, by biting, to the body of the female. His mouth fuses

with her skin, and the bloodstreams of the two

fishes become connected. The male is now totally

Also known as spook fish, the Barreleye is an incredibly strange looking creature. They have two upward facing eyes to scan for prey. Their distinctive feature, however, is the transparent dome that encases them.

Although it may not be as physically imposing as some of the other creatures on this list, the Blue Ringed Octopus is easily one of the most dangerous animals in the ocean. Its venom is extremely potent and because there is no antivenin, it is certainly a good idea to steer clear.

Ocean Light ZonesThe zones of light in the ocean are dependent on the depth and water quality. The photic zone, is the surface layer of the ocean that receives sunlight. Approximately the uppermost 260 feet of the ocean, which is sufficiently illuminated to permit photosynthesis by phytoplankton and plants, is called the euphotic zone. Sunlight insufficient for photosynthesis illuminates the disphotic zone. The thicknesses of the zones vary with the intensity of sunlight as a function of season and latitude and with the degree of water turbidity. The bottommost, or aphotic, zone is the region of perpetual darkness that lies at the bottom of the ocean.

Ocean Depth ZonesScientists have divided the ocean into five main layers. These layers, known as “depth zones,” extend from the surface to the most extreme depths where light can no longer penetrate. These deep zones are where some of the most bizarre and fascinating creatures in the sea can be found. As we dive deeper into these largely unexplored places, the temperature drops and the pressure increases at an astounding rate. The following diagram lists each of these zones in order of depth. The surface of the open ocean is known as simply the “pelagic” zone, hence the use of the word pelagic in each of the following zones. The word pelagic simply means “of, or relating to the open seas.”

PlanktonPlankton is a diverse group of organisms that float with the ocean current because they are too weak to swim. Plankton comes in many varieties including zooplankton and phytoplankton. Phytoplankton is the plant-like varieties while zooplankton are the animal-like varieties. They are a crucial part of the ocean food web. Planktons uses as a resource to human has only been recently discovered, but it may prove to be not only a source of food for a growing global population, but an important energy resource as well.

NektonUnlike the varieties of plankton that are non-swimmers, the term nekton refers to the group of organisms that are “free-swimmers,” or are strong enough to swim freely and independently of the ocean currents.

BenthosBenthos is a community of organism that live on or near the ocean floor. They are mainly confined to slow or scurrying movement, and often like to burrow into the sea bed. They are called benthos because the ocean floor is also referred to as the benthic zone, and can also be considered “bottom feeders.” It is important that you know the difference between plankton, nekton and benthos both in terms of movement and their location in the ocean.