What are ecological pyramids? Describe the different types of ecological pyramids

Ecological pyramids
We can compare the trophic levels in a food chain using ecological pyramids.

Pyramid of numbers
A pyramid of numbers allows to compare the number of organisms present in each trophic level at a particular time.

Pyramid of biomass
A pyramid of biomass allows us to compare the mass of organisms present in each trophic level at a particular time.

Variations in ecological pyramids
Most ecological pyramids are pyramid-shaped, but there are important exceptions.

A pyramid of numbers may be upside down or inverted if organisms of one trophic level or many small organisms of another trophic level feed on large organism of another trophic level. In this case, the pyramid of numbers is inverted.

Pyramids of biomass for rapidly reproducing organisms are also not pyramid-shaped. Since the pyramid of biomass is based on standing mass, it does not take into account the rate of reproduction of organisms.

Pyramid of energy
The total energy in the various trophic levels of a food chain can be represent in the form of a pyramid. This is called the pyramid of energy.

What is the relationship between a predator and a prey? Two predators with the same prey?

What is the relationship between a predator and a prey?
A predator is an organism that kills and feed on other organisms. The organisms that are eaten are called the prey.



Two predators with the same prey.
However,this cycle changes when another predator of the same prey is introduced into the same biotic environment.Prey will be hunted and fed on continuously until the number falls until it is almost extinct.Food is now scarce for both predators.Therefore the population of both predators will drop as there is hardly any prey.This fragile cycle might break as time passes and both prey and predator goes extinct unless predators hunt for a different prey and the prey evolves to be able to evade the predator.

How do energy and nutrients flow through an ecosystem? Give an example of a food chain, and food web.

How do energy and nutrients flow through an ecosystem?

The living organisms in any ecosystem are made up of producers, comsumers and decomposers. Energy and nutrients are transferred from producers to consumers to decomposers through feeding.

Producers:

Producers convert energy from the sun or the light energy into chemical energy and store it as food during photosynthesis. Producers are mainly green plants, but algae and certain bacteria that can photosynthesise are also producers. Producers are the onlt organisms that can manufacture or produce complex organic food from inorganic raw materials. Hence, producers either directly or indirectly affect the lives of other organisms because they provide energy and oxygen.

http://www.flickr.com/photos/valentins/147656936/

Consumers:

Consumers obtain their energy by feeding on the other organisms. All animals are therefore consumers. Plant-eaters or herbivores feed directly on plants, hence they are known as primary consumers. Meat-eaters or carnivores feed on other animals . Carnivores that feed on herbivores are known as secondary consumers. Carnivores that feed on other carnivores are known as tertiary consumers.

http://www.fermes-ouvertes.fnsea.fr/animaux/images/ruminant.jpg

http://www.flickr.com/photos/k9rescue/352112722/

Decomposers:

Decomposers obtain energy by breaking down lead organisms, faeces and excretory products. When dead organisms and waste materials locked up in them are released. These materials, such as inorganic nutrients, carbon and nitrogen compounds, return to the physical environment and are used again by green plants. Fungi, bacteria and earthworms are examples of decomposers.

Food chains:

We can represent the feeding relationships between organisms in an ecosystem using food chains. A food chain is a series of organisms through which energy is transferred in the form of food. Each organism in a food chain feeds on the organism before it and provides food for the organism after it. A food chain always begins with a producer. Remember, producers are the only organisms that can manufacture organic food from inorganic raw materials.

An example would be:

Source: http://www.eduweb.com/

Food web:

n a community, food chains are interlinked to form a food web. There may be two or more food chains in a food web. Here is an example of a food web:

Source: http://www.woodlands-junior.kent.sch.uk/

Are organisms interdependent? Why?

Are the organisms interdependent?

The organisms in any habitat are never completely independent. The life of each organism depends on, and is influenced by, other organisms around it. We say that organisms are interdependent.

How do the physical features of the surroundings affect organisms? What are these physical factors?

• How do the physical features of the surroundings affect organisms?
  The physical features of the surroundings and the nature of the soil determine the types of plants found in the region. Since animals rely directly or indirectly on plants for food, the animals that live in a region determined by the plants growing in that region. Organisms found in a region are usually adapted to the physical features of their environment.
  
  The physical factors are:
  


• Light intensity - Light intensity affects the distribution and growth of both plants and animals. Green plants exist only where theere is an adequate suppl of sunlight. Some plants develop adaptations to reach the light. For example, climbing plants may twine around or grasp a support to pull themselves upwards. However, bright light causes plant stems to grow more slowly. This is why plants growing in the open usually end up shorter than those in the shade. Certain plants have develop adaptations to block or screen off excessive light. For example, some plants have a dense covering of hairs on the leaf epidermis or a thick-walled cells called the hypodermis just beneath the epidermis. These adaptations protect the plant by screening off excessive heat and reducing the rate of transpiration. Many animals need sunlight to see in order to catch their prey or to detect predators. However , some animals develop special adaptations for living in dark caves. they locate prey in the dark by bouncing sound waves off objects around them.


• Temperature - Temperature affects the rate of reaction of enzymes, which control metabolic or physiological activities of plants and animals. Most organisms cannot tolerate extremes of temperatures. Temperatures that are too high or too low would kill an organism. Many flowering plants are adapted to changing seasons. Such plants are able to survive through a hot and dry seasons or through winter by storing food in underground storage organs, shedding leaves to reduce water loss, or foaming seeds which are resistant to heat, cold or drought, just before these seasons arrive.


• Amount of water available - No organisms can live long without water. Hence, the amount of available water is one of the major factors affecting the number and location of the plants and animals in a region. The amount of available water depends on the amount of rain and pattern in which rain falls throughout the year. Some organisms are adapted to survive under the conditions where there is a limited supply of water. For example, camels are able to survive for many days in the desert without water because they can drink more than 100 litres of water because they when available, then they go for long periods without drinking. Some plants, known as xerophytes, are adapted to survive prolonged drought. They reduce their rate of transpiration by shedding their young leaves or by developing leaves reduce to spines, stems become fleshy(storing up much water) and green stems also take over the function of photosynthesis from the leaves. On the other hand, there are other plants that live in water or in very wet places. These are called hydrophytes. Hydrophytes may be completely submerged, for example, hydrilla; partially submerged, for example, water lily; or free floating, for example, water hyacinth. Mangrove plants, such as Avicennia, have their roots buried in oxygen-poor mud. Special breathing roots called pneumatophores project above the mud srface. Pneumatophores have openings through which oxygen passes downwards to the whole root system. Aquatic animals also show adaptive features for living in water, such as gills, for absorbing oxygen or special structures for swimming. For example, frogs have webbed toes and fish have fins for swimming.


• Oxygen content - Most organisms are aerobic, that is, they require oxygen for respiration. They cannot survive in enviroments of low oxygen content. However, some aerobic organisms can survive in enviroments of low oxygen content. This is because they possess mangrove plants adaptations for obtaining sufficient oxygen, for example, oxygen content are usually air-breathers. They can come to the surface of the water to gulp air.


• Salinity - The salinity or salt concentration of water is an important factor affecting aquatic organisms. Animals living in sea water tend to lose water by osmosis as seawater contains a higher salt concentration than the cytoplasm of animal cells. Saltwater or marine fishes have a waterproof coat consisting of closely-fitting scales covered by a slimy mucous material. This reduce the rate of water loss. The cytoplasm of the cells of freshwater organisms usually has a higher salt concentration than the surrounding water. Hence, water tends to enter this organisms by osmosis. The cells of freshwater plants have rigid cell walls that prevent them from bursting. Protozoa such as Amoeba have contractile vacuoles to remove the excess water that enters them by osmosis. Most freshwater fish possess slimy scaly skins which keep water from entering their cells.

• pH - The term pH refers to the acidity or alkalinity of a solution. The pH of soil water or the water in freshwater ponds or the sea affects the types of organisms thet can live in such ebvironments. Aquatic organisms are sensitive to the pH of the water in which they live and may die if there are drastic or sudden changes in pH. Seawater is alkaline with a pH of about 8. The pH of seawater does not vary that much. In freshwater ponds and streams, the pH varies from one region to another. Changes in pH do occur, especially if the pH of the water depends on the amount of hydrogencarbonates present in it. For example, in strong daylight, photosynthesis in plants uses up the carbon dioxide in the water, making the water more alkaline. During the night, photosynthesis stops and the carbon dioxide produced in respiration makes the water more acidic. For most types of freshwater organisms, nuetral or nearly nuetral water provides optimum living conditions.

What comprises ecology?

Ecology is the study of the continuous interaction between organisms with one another, as well as their surroundings.

Ecology comprises of the followings:

• Habitat -The place where an organisms lives.
• Population -Make up of a group of organisms of the same species living living in a particular habitat.
• Community -Make up of all populations of organisms living and interacting with one another in a particular habitat.
• Ecosystem -Make up of a community and its physical or abiotic enviroment together.