Supports Diversity of Life

In the ocean, we are the aliens. As land dwellers, we are easily surprised by the great diversity of ocean life. Life in the ocean has had billions of years to adapt and evolve which results in lots of different, wonderful, and sometimes strange, forms. Life originated in the ocean and all the different types of species that survive today evolved from ocean life.

Biology tries to make sense of diversity by sorting and categorizing life. As our knowledge progresses, the naming system gets better at reflecting the similarities and shared characteristics and common ancestors of different species.

The order of naming life goes as follows:

Kingdom → Phylum → Class → Order → Family → Genus → Species.

For example, the classification for humans is:

Kingdom: Animalia → Phylum: Chordata → Class: Mammalia → Order: Primates → Family: Hominidae → Genus: Homo → Species: Homo Sapiens

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It is through this naming that we are able to identify features of all living things. For example, being a part of the Animalia kingdom means we are an animal, not a plant. We have this in common with all other members of the Animalia kingdom. By being a part of the Phylum Chordata, means that we are vertebrates. This separates us from all the creatures that do not have a spine.

By being a part of the Class Mammalia means that we have the share characteristics that define a mammal: live birth, mammary glands, vertebrates, air breathers, and have hair. Any organism in the Mammalia class will share these five characteristics. Each grouping level has diversity within it, and the broader the grouping the greater the difference between groups. Even though both humans and dolphins are mammals, we are still very much different creatures.

The diversity of organisms is also greatly affected by where they are found. Organisms are specifically adapted to survive in their home range and these adaptations affect how the organism looks and functions. For example, whales, like the beluga whale, that live in the Arctic have much more blubber than a Bryde whale, which lives in tropical water. Whales are all a part of the family Cetaceans, with porpoises and dolphins, but each genus and even species has been specially adapted over millions of years to ensure their best survival. All of this diversity comes from the ocean.

In the ocean, we also see animals with special adaptations. Adaptations are characteristics or traits that help an animal survive, like how you have special thumbs to pick up your food with. In the ocean, these adaptations can change depending on where an animal is found. Sometimes it will be physical features in animals or it might be a special way that they act.

For example, smaller fish living in the wide, open ocean often swim together in a behavior called schooling. Take a look at this picture. Why would these fish want to swim together when they live in a habitat like this?

Fish that live in the big open ocean could face a predator coming from any direction. By schooling together these fish have a better chance of spotting dangers or having their neighbor eaten instead of them! This is a behavioral adaptation for surviving in the open ocean.

Sometimes these adaptions are physical. Beluga whales live in the cold Arctic ocean and have many different adaptations for surviving in this extreme environment. One of their biggest adaptation is their blubber! Blubber is a thick layer of fat that surrounds the beluga's body to keep them warm, like when you wear a thick jacket when it is cold outside.

There are lots of different kinds of habitats like there are lots of different kinds of animals. These habitats are described by the amount of salt, light, heat, and pressure that they have. The Arctic ocean, covered with ice and cold water, is very different from a warm, tropical coral reef. Some animals live among the rocky ocean floor while others live in the wide, open ocean where there is nowhere to hide. Some animals even live so deep down that there is no light and a huge amount of pressure. What sort of adaptations do you think these animals would have?

Sometimes diversity can be vastly different within one area of the ocean, due to zonation. Zonation is where two separate zones are created in one area. Zones can be created by geological structures, pressure, salinity, or temperature.

One of the best examples of this is the intertidal zone, found on coastlines. In the intertidal zones, the level of the tide influences which organisms are able to survive in each zone and how they are adapted to living there. For example, snails can be found at high tide, mid tide, and low tide because they are able to retain moisture in their shells to protect them from the sun exposure of high tide zone. Sea cucumbers, on the other hand, can only be found in areas that are always covered by the tide because they do not have external protection from the sun or lack of water that would be located at the high tidal zone.

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Different ocean zones are also created by pressure. Pressure increases as you go deeper into the ocean. There is also less light deep in the ocean. Animals in the Abyssal zone are specifically adapted to survive in these harsh conditions. They would not be able to survive outside of their zone, while Mesopelagic animals certainly could not survive any deeper than the open ocean either.

The same applies to animals living in freshwater conditions. Let's take a look:

This diversity is connected and interacts through the ecosystem food web and the trophic pyramid. The food web demonstrates how each species is connected through predator and prey relationships. The Trophic pyramid demonstrates how energy and nutrients move through the ecosystem in a kind of pyramid hierarchy. Microbes, including photosynthetic bacteria and micro-algae, are at the base of almost all ocean food chains. Marine microbes are globally important in cycling elements like nitrogen, carbon, and oxygen through the food web. Energy is passed up the food chain with loss of heat energy and loss of biomass at each trophic level.

In large parts of the ocean, such as the open ocean and deep ocean, life can be really patchy. Necessary nutrients or the lack of sunlight can limit organism growth. There are patches of the ocean where currents mix or nutrient-rich water from the deep is brought up to the surface. Distances between these patches can be huge so many ocean species are adapted to travel fast and far to find food.

On the other hand, there is the world greatest daily migration (movement) of organisms: the vertical migration. It also is one of the slowest migrations. Every day just before dawn large animal plankton (zooplankton) and many fish sink down in the water column. They hide in the dark where it is safer from predators during the light of the day. Then in the dusk, they migrate back up to feed on the photosynthetic algae and bacteria that were busy feeding from the sun during the day. These ecosystem interactions drive the movement of energy through the food chain as well as diversity between animals to adapt for best survival.


The more we learn about ocean ecosystems, the more we learn how they provide for biodiversity (including us). Learning about individual species helps us understands how ecosystems are interconnected and interdependent.

70% of the Earth's surface is covered in water. 97% of that water is the ocean. In the ocean, there can be found a huge variety of different organisms, plants, and animals alike.

This diversity is connected and interacts through the ecosystem food web and trophic pyramid. The food web demonstrates how each species is connected through predator and prey relationships. The trophic pyramid demonstrates how energy and nutrients move through the ecosystem in a kind of pyramid hierarchy. Energy is passed up the food chain with loss of heat energy and loss of biomass at each trophic level.

Microbes, including photosynthetic bacteria and micro-algae, make up most of the biomass in the ecosystem. They are the base of almost all ocean food chains. Marine microbes are globally important in cycling elements like nitrogen, carbon, and oxygen through the food web.

The ocean ecosystems, where this diversity thrives, are defined by the environmental abiotic factors: dissolved oxygen, temperature, and salinity.

Dissolved oxygen: the amount of oxygen that is dissolved into the water. It is measured in milligrams per liter (mg/L). Oxygen gets into the water in a number of different ways. Oxygen will dissolve from the atmosphere and mix with the surface of the water. Algae and other photosynthetic plants produce oxygen as a result of photosynthesis. The movement of waves and wind help to distribute this oxygen. This amount of dissolved oxygen is heavily influenced by temperature. When the temperature is higher, the oxygen dissolves at a lower rate. This means that warmer water holds less dissolved oxygen than cold water. Dissolved oxygen can also be limited by too many nutrients in the water (called eutrophication) which can lead to algae blooms. When the leftover algae die and sink to the bottom, they are decomposed by bacteria that consume oxygen in the process.

Temperature: the temperature of the water is critical to evaluating its health. Just as with pH, organisms have a temperature range in which they are adapted to living. By knowing the temperature we can determine which organisms can best survive in a given environment based on their home range, the range they are adapted to survive in. We can also determine how much dissolved oxygen is in the water based on the temperature. When the water is warmer, the amount of oxygen that can be dissolved in the water decreases. Therefore, there is less oxygen in warmer water.

Salinity: this is the measure of the concentration of salt in the water. In the ocean, it is usually constantly between 30 to 35 ppt (parts per thousand). Salinity can vary depending on the location and temperature. Estuaries, for example, are where the ocean and rivers meet and mix. Salt content in estuaries varies depending on whether it is a saltwater or freshwater estuary. Local geology high in soluble materials, like carbonate, is another natural factor that may influence salinity. Unnatural factors such as fertilizers from agriculture, sewage, road runoff with automobile fluid, and de-icing salts can all influence salinity. Organisms are specifically adapted to survive in a specific range of salinity. Animals adapted for freshwater could not survive in the salty ocean, and vice versa. Additionally, too much salinity in a body of water means that no organisms could survive.

Ecosystems are also defined by the zonation patterns that define them, and influence organism distribution and density. One of the strongest examples of this is the intertidal zone found on a coastline. The zonation is created by the tides, wave, and substrates that affect each level of the intertidal zone. 

Shoreline ecosystems are incredibly important because these species create complex three-dimensional spaces which act as habitats for other species to live, making even more space for life in the ocean. For example, sea-grass meadows, kelp forests, mangroves, and coral reefs provide this 3D space. They also fix a lot of carbon through photosynthesis, this makes them very productive ecosystems. Even though they cling to the very edges of the continents, and do not cover much ocean area, they are very important at sustaining life, cycling nutrients, providing food and shelter, taking up carbon dioxide, release oxygen, and allow the mutual relationship to co-evolve.

Essential ecosystems are spaces at risk because they are in shallow water, often found close to us and because they are negatively impacted by our uninformed actions. The more we learn, the more important they become as priorities of conservation and restoration action. The more we put our learning into practice, the better we can care for the ecosystems and the diversity of life they support.

There is another type of zonation that can occur due to changes in temperature which can potentially be very dangerous for an ecosystem. Stratification occurs when cold dense salt water and less dense freshwater mix, creating two separate layers with the freshwater is on top. This is natural to see in places like an estuary, where the freshwater river meets the ocean. Stratification can create two separate zones in the same geographical location because of this difference in temperature. It can, however, cause algae to increasingly grow due to nutrient overload, and the lower colder habitat to collapse. 

Stratification can also be caused by a difference in temperature when an extreme difference in heat can cause the formation of distinct, non-mixing layers of water. This stratification causes chemically and biologically different regions in one area of water.

Diversity leads to unique relationships between organisms that are not seen on land, such as the crab and the sea anemone working symbiotically to survive.

Diversity is also influenced by the geographic location of the ecosystem. Organisms develop unique adaptations to best survive in their given environment, and this is most evident in the case of extreme environments. Mammals that call the Arctic their home are an excellent example of the diversity that may arise under environmental pressures.

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