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In Conservation
Marine biology is the science of saltwater and everything that lives, moves, and filters through it. The word "marine" in this sense refers specifically to saltwater that you find in oceans, not freshwater, which is found in lakes.
When you look at a globe, you can see that nearly three quarters of the Earth's surface is covered with water. Scientists believe life on Earth got its start in the ocean, and gradually adapted to life on land. Some land-based organisms eventually returned to the water, like dolphins and whales. Tiny ocean plants, called phytoplankton, produce most of the oxygen in the air we breathe. When producing oxygen, these plants soak up carbon dioxide, removing this gas from the air.
The ocean is always in motion: currents move water around the globe. Water evaporates and rises into the atmosphere where it will eventually fall as rain and snow. Cold water sinks in the ocean, warm water rises, and this constant movement distributes heat and nutrients around the globe.
In this course, you will learn about life in the ocean depths, at the Polar extremes, in coral reefs, estuaries, and in the open sea. You will learn about plants large and small, marine birds, reptiles, invertebrates and fish. You will learn how all these organisms connect with each other in the marine biome, and what threats are facing these ecosystems.
The Ocean Environment
Over millions of years, water running off the land dissolved salt from rocks and carried it downstream into the ocean. Salt also poured out of volcanic vents deep under the ocean. The sun and heat went to work and evaporated the water into the atmosphere, and the salt stayed behind in the sea. Today, the average salt level, or salinity, in the ocean is 35 parts per thousand, or ppt. Some oceans, like the Black Sea, are less salty and some, like the Dead Sea, are even more salty than average. The higher the salinity of the water, the denser the water is (higher density or specific gravity). In the Dead Sea, the water is so salty and dense that people can float on top of the water effortlessly, like a cork.
Not all organisms can live in a high salinity environment. People, for example, can't survive in saltwater. Since you have no special adaptations to remove salt, if you drink too much seawater, your kidneys will try to flush the excess salt out as quickly as possible through urine, and you would lose more water than you originally drank, leaving you dehydrated. If you didn't correct the situation by replacing fluids with fresh (non salty) water, your organs would eventually shut down and you would die.
Living in the ocean requires special adaptations, like a tolerance for salt or a way to remove the excess effectively, the ability to move through the water, find food, hide from predators, and locate a mate.
On land, we tend to think that ecosystems develop in certain geographical areas, but in the ocean, distance doesn't matter as much as depth. The ocean environment changes as you move deeper into the water. It becomes colder and darker. The pressure is higher and there is less oxygen dissolved in the water. The living conditions are so different at different depths that plants, bacteria and animals can usually only live in certain zones. Scientists call this vertical stratification.
Science and Marine BiologyScientists generally agree that all life, from algae to whales, all descended from the same original ancestor. This one ancestor reproduced, and its offspring reproduced.
According to the theory of evolution, as generations passed, the descendants changed, or evolved, until they did not resemble one another at all. Once these distant relatives weren't able to reproduce with one another, they became entirely different species. Scientists study all the different organisms existing today and analyze the traits that they have in common to group them into families. Although scientists argue about how evolution happens and how long the process takes, they do agree that change is constant and that it's going on right now. Species which did not change, or adapt, to changing circumstances eventually died out and became extinct.
An adaptation is a successful change that provides an organism with an advantage for living in its environment. The theory of evolution argues that organisms that are best adapted to their environment have the best chance of surviving long enough to reproduce. When organisms don't have to work as hard to get food or fight predators, they have more energy for reproduction, which means they can have more offspring. Over time, the descendants of well adapted organisms will increase and multiply while less successfully adapted organisms spend more time just trying to survive, and will eventually die out. This process is called natural selection.
What is Ecology?Ecology is the study of relationships between living organisms and their environment. Instead of looking specifically at one type of plant or fish, ecologists look at the big picture. For example, if one type of fish usually eats a lot of algae, but the fish suddenly disappears from its ecosystem, the algae might grow out of control. It could cloud the water and keep the plants below from being able to use the sun for energy. Lower plants might die off, and other fish that used the plants for food and shelter would suffer.
Understanding the relationships between species has helped scientists derive useful medicines from natural sources, like a substance in horseshoe crabs that is now used in leukemia treatments.
Lesson 1 : Introduction
Marine biology is the science of saltwater and everything that lives, moves, and filters through it. 40 Total Points
Complete Assignment: An Introduction
The area where old crust is sinking under another slab of crust is called a subduction zone. Subduction zones create such deep trenches that they are all below sea level. 35 Total Points
The term current refers to the motion of water. On land, the motion of water is usually driven by gravity: rain falls from clouds and then runs downhill toward lakes and to the ocean. 35 Total Points
A species is a group of organisms that are able to successfully reproduce with one another. 35 Total Points
The jellyfish, for example, contracts its umbrella shaped body to propel itself through water. Other invertebrates use water pressure, shell, or cups to support themselves. 35 Total Points
There are seven main classes and superclasses of vertebrates that include fish, reptiles, amphibians, birds and mammals. 35 Total Points
The study of fish is called ichthyology, and ichthyologists have grouped all fish into three main categories: jawless, cartilaginous, and bony. 35 Total Points
Video
Review 2 Articles: 20 Weirdest Fish in the Ocean; Marine Fish Species
Complete: Lesson 7 Assignment
Complete Exam: Lesson 7: Marine Fishes
Mammals, whether they live on the land or in the sea, are all vertebrates (meaning they have a backbone and a brain). 35 Total Points
Video
Review Article: List of Marine Mammals
Complete: Lesson 8 Assignment
Complete Exam: Lesson 8: Marine Mammals
A biome is a large geographical area that contains several different ecosystems. All the plants, animals and other organisms that live in a biome are adapted to that environment. 35 Total Points
The intertidal zone (also called the foreshore, seashore and the littoral zone) is the area that is exposed to air at low tide and underwater at high tide. 34 Total Points
An estuary is one type of intertidal zone, where a river meets the sea: freshwater meets saltwater in a bay, lagoon, sound, or slough. 35 Total Points
Coral reefs are usually found in the tropics, and although corals make up a big part of the reef, they are just one component of an enormous community. 35 Total Points
Many marine scientists think that most reefs start out as fringe reefs, and over time, the coral grows out and away from land. As it gets farther from land, the reef's diameter expands and a large lagoon forms. 35 Total Points
Although the two poles have a lot of similarities, like very cold weather and extreme living conditions, life in the two regions was shaped by a different series of circumstances. 35 Total Points
The open ocean is the largest biome in the world by volume, but in terms of the quantity of life, the Pelagic resembles the most enormous desert ever known. 35 Total Points
The Benthic Zonerefers to the sea floor, which extends from the tidal areas all the way down to the deepest trenches on the planet. 35 Total Points
Some of the major threats facing the oceans include climate change, pollution, nutrient runoff, garbage dumping, overfishing, and ship strikes. 110 Total Points
Complete: The Final Exam
Total Course Points : 674
By successfully completing this course, students will be able to: