Here Are The Concept Of Biological Association


In a community, there were an exist of different kind of biological association betweeb organisms of different species. Some of these biological association are beneficial some are neutral while others are harmful.


Symbiosis is a close association between two organisms in which both of them benefit from each others. Symbiosis is a beneficial association and each member is called Symbiont.

Examples are:

1. ALGA AND FUNGI IN LINCHEN: A linchen is made up of two organisms namely, a fungi and a Green alga which live in a close association. In this association, the alga benefits because the fungus encloses and protect it from physical damage and from drying up.

2. PROTOZOA IN THE INTESTINE OF TERMITES: The protozoa help the termite to digest the cellulose in the food while the protozoa are protected by the termites.

3. NITROGEN FIXING BACTERIAL IN THE ROOT NODULES OF LEGUMINOUS PLANT: A bacterial called Rhizobium Leguminosasium living in the root nodules of leguminous plant obtain nutrients from the cells of the lost plant, grow and multiply or reproduce there.

4. BACTERIAL IN THE RUMEN OF RUMINANTS: Bacterial and other protozoa in the rumen of ruminant animals like Cattle, Sheep and Goat help the ruminant to digest cellulose to sugar, synthesis amino acids and vitamins from other substances while the ruminant in turn produces food and shelter for the bacteria.


Commensalism is an association between organisms living together in which only one (Commensal) benefits from the association while the other is nether benefited nor harmed.

Examples of commensalism:

1. REMORA FISH AND SHARK: The Remora fish attaches itself to the body of a shark which carries it about. The Remora fish feeds on the food particles left over by the shark.

2. OYSTER AND CRAB: The habitation of a crab is in Oyster shell in which the crab is protected yet no harm is done to the Oyster.

3. MAN AND INTESTINAL BACTERIAL: Some bacterial in the large intestine of man feed on digested food. The bacterial receive food and protection from the man whereas the man neither gain nor suffers any disadvantage from the presence of the bacterial.


Parasitism is a close association between two organisms in which one, known as the Parasite lives in or on end feeds at the expenses of the other organisms which is known as the Host. The parasite benefits from the association while the host usually suffers harm or may die.

Examples are:

1. MAN AND TAPEWORM: The tapeworm is a parasite that lives in the small intestine ‘of man where it derives the benefits of a habitat, protection and food.

2. MISTLE AND FLOWERING PLANT: The mistletoe is a plant parasite that lives on other larger flowering plant. The mistletoe benefits because the host gives it support and raises it upon to a position from which it can receive sunlight.


Predation is a type of association between two or more organisms in which the Predator kills other called the Pray and directly feed on it. The predator which is usually larger in size and always stringer than the pray benefits by deriving its food while the pray is completely eliminated.

Examples of predator are:

1. THE HAWK AND CHICKS OF DOMESTIC FOWLS: The Hawk is the predator that catches, kills and eat the pray (Young Chicks) of domestic fowls. The hawk is stronger and bigger than the chicks, the hawk benefits while chicks are completely eliminated.

2. THE LION AND GOAT: The lion is the predator that catches, kills and eats the pray (goat). The lion is stronger and bigger than the goat, the lion benefits while the goat is completely eliminated.


Competition involves the interactions among two organisms of the same or different species in which one outgrows the other and survives while the other can neither grow nor survive. Competition is often based on limited environmental resources which can be in short supply such as food, water, nutrient, gasses, light and space.

Examples are:

1. FLOWERING PLANT AND GRASSES: The flowering plants due to it’s size and numerous branches and leaves are capable of eliminating the grasses by depriving the grasses of nutrient space and sunlight.

2. DOMESTIC FOWLS AND THE YOUNG CHICKS: The adult domestic fowls are capable of eliminating the young chicks by depriving chicks of food in the pen. The young chocks may eventually die because they may not have access to the limited food available in the feeder.


Adaptation is defined as the ability of an organism to live successfully in a particular habitat as a result of it’s structure appearance and behavior. In other words, adaptation is the change in structure, function and behavior of an organism in order to adjust or survival in it’s environment.



  • Possession of streamlined body for easy movement in water e.g. Tilapia fish and Toad.
  • Possession of fins for movement as in the case of fish and webbed toes as in toad.
  • Possession of gills for gaseous exchange in fish and tadpoles.


  • Possession of powerful limbs for movement e.g. Mammals.
  • Possession of lungs for gaseous exchange e.g. Mammals, Birds, Reptiles and Amphibians.
  • Possession of sweat glands for excretion and cooling e.g. Mammals.
  • Possession of hairs for body temperature regulation.


  • Possession of wings for flight e.g. Birds.
  • Possession of hollow bones to make them light e.g. Birds.
  • Possession of bright colour as well as camouflage e.g. Chameleon.
  • Possession of powerful limbs, claws and tails for climbing and piecing e.g. Birds, Monkeys and Baboons.



  • Possession of waxy cuticles on leaves top prevent wetting e.g. Water lettuce.
  • Possession of long stem and flower stalk to expose the flowers and leaves e.g. Water lily.


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