Lesson Notes By Weeks and Term - Senior Secondary School 2






    • Modern Biology for Senior Secondary Schools by S.T. Ramalingam
    • Essential Biology by M.C Michael 
    • New School Biology by H. Stone and Cozen
    • SSCE Past Questions and Answers
    • New System Biology by Lam and Kwan 
    • College Biology by Idodo Umeh
    • UTME and Cambridge Past Questions and Answers 
    • Biology Practical Textbook


WEEK NINE & TEN                 




  • Definition of Adaptation 
  • Adaptation of animals
  • Adaptation of plants 
  • Adaptation of animals in marine habitat
  • Adaptation of Plants in Aquatic Habitat 
  • Estuarine habitat
  • Characteristics of estuarine habitat
  • Plants and animals distribution in estuarine habitat



Adaptation is defined as the ability of an organism to live successfully in a particular habitat as a result of its structure, appearance and behaviour. It is expected that every organism must adapt to its environment in order to survive. Plants and animals possess certain features which enable them to adapt to either aquatic or terrestrial habitats.


Animal Adaptation 

(1) Adaptation of Animals to Aquatic Habitat

(i) Possession of streamlined body for easy movement in water, e.g. Tilapia fish and toad.

(ii) Possession of fins for movement as in the case of fish and webbed toes as in toad

(iii) Possession of gills for gaseous exchange in fish and tadpoles.

(iv) Possession of swim bladder for the purpose of buoyancy in water, e.g. Tilapia fish.

(v) Possession of tail for swimming, e.g. tadpoles.

(vi) Possession of sticky undersurface for attachment to surfaces of objects, e.g. snails and flatworms.

(vii) Possession of suckers or hairs for attachment to vegetation so as to avoid being swept away by water current,

e.g. leeches.


(2) Adaptation of Animals to Terrestrial Habitat

(i) Possession of powerful limbs for movement, e.g. mammals.

(ii) Possession of lungs for gaseous exchange, e.g. mammals, birds, reptiles and amphibians.

(iii) Possession of sweat gland for excretion and cooling, e.g. mammals (iv)Possession of hair as in mammals and that of feathers as in birds for body temperature regulation.

(v) Possession of skin as in mammals and cuticle by insects to protect and prevent drying up and injury.



  1. What is evaluation?
  2. Describe how tilapia adapts to water. 


(3) Adaptation of Animals to Aboreal Habitat

{i) Possession of wings for flight, e.g. birds.

(ii) Possession of hollow bones to make them light, e.g. birds.

(iii) Possession of bright colour as well as camouflage, e.g. chameleon.

(iv) Possession of powerful limbs, claws and tails for climbing and piercing, e.g. birds, monkeys and baboons.

(v) Possession of streamlined body for easy flight, e.g. bird

(vi) Possession of strong muscles and  tendon to ease flight, e.g. birds.

(vii) Feeding mainly on grains to provide energy required for flight, e.g. birds.


Plants Adaptation     

 Adaptation of Plants to Aquatic Habitat

(i) Possession of waxy cuticles on leaves to prevent wetting, e.g. water lettuce

(ii) Possession of long stem and flower stalk to expose the flowers and leaves e.g. water lily.

(iii) Possession of adventitious roots, e.g. water lettuce.

(iv) Possession of air floats in the leaves and stems for buoyancy, e.g. water hyacinth.

(v) Possession of breathing roots for gaseous exchange, e.g. white mangrove 

(vi) possession of air spaces in the tissues for buoyancy, e.g. water lettuce.


Adaptation of Plants to Terrestrial Habitat

(i) Possession of extensive root system for  anchorage and water absorption, e.g. mahogany.  

(ii) Possession of thick barks on the stems to protect internal tissues.

(iii)Possession of numerous leaves to enhance better photosynthesis.

(iv)Possession of succulent stems by desert plants to enable them store excess water.

(v) Possession of tiny and scanty leaves by desert plants to reduce water loss through transpiration.

(vi) Possession of thick, waxy cuticles on leaves to prevent water loss through transpiration.



  1. Mention the features that adapt hydrophytes to water. 
  2. Mention five adaptive features of arboreal. 


Special Adaptation of Some Organisms 

  1. Adaptation of Tilapia Fish for Movement

These adaptive features are:

(i) Possession of fins for movement in water.

(ii) Presence of streamlined body for easy movement.

(iii) Possession of lateral line system for detection of vibration in water.

(iv) Possession of powerful tail which is used for propelling the fish forward.

(v) The direction of the fins and scales backward aid easy movement through water.

(vi) Possession of large eyes without eyelids which enables it to see predators and preys easily.

(vii) Possession of swim bladder which aids its buoyancy in water.

(viii) The silvery-white colour of the body below and black above prevent it from being seen by enemies.


  1. 2. Adaptation of Birds for Flight

These adaptive features are:

  1. i) Possession of light body weight to ease flight.
  2. II) Possession of feathers for protection.
  3. ii) Possession of wings for flight.
  4. v) Streamlined shape of the body to ease flight.

  1. 3. Adaptation of Toad or Frog for Food, Protection and Movement


For Food 

(i) It possesses special olfactory organ in the head for smelling/perceiving the odour of its food.

(ii) It has the ability to draw eyes in so that they make bulges in the root of the mouth which help to prevent their prey from escaping and help in swallowing.

(iii)The tongue is attached at the front of the mouth which can be rapidly extended to capture/trap prey.

(iv)The tongue is long and sticky to hold prey.

(v) The tongue which is long helps in catching prey.


For Protection 

(i) The skin is slimy with mucous gland which makes the animal difficult to be  caught by predators.

(ii) Slimy fluid keeps the skin moist and prevents the skin from drying up.

(ii)Toad has poison glands on the skin which is poisonous and distasteful to the predators.

(iii) Brownish colour or cryptic colouration helps to blend with the colour of the surroundings and this prevents them from being noticed by predators.

(iv) Ability to alter colour to blend with the background 

 For Movement

i)A toad has long hind limb with powerful muscles which enables it to hop or jump efficiently.

  1. ii) Absence of tail enhances hopping or jumping movement.

iii) Webbed hind limb can be used as Paddle for efficient swimming in water.

iv)The stout and short nature of fore limb absorbs shock on landing.  

  1. v) It possesses streamlined body for easy movement and swimming.



  1. Highlight the adaptation of birds for flight. 
  2. Mention the features of toad and their uses


Adaptation of Animals in Marine Habitat   

 Animals including barnacles, fishes, crustaceans etc. found surviving in marine habitat do so with the following adaptive features;

  1. Barnacles have i. protection mantle for attachment to rock shore and water retention ii. Cilia for feeding. iii. Shell that prevents dessication (drying up)
  2. Fishes possess i. reduced or no kidney to retain urea in their body to cope with high salinity e.g. cartilaginous fishes like shark, dogfish e. t. c. ii. Salt secreting glands in their gills or eyes for maintaining osmoregulation (salt balance) e.g. bony fishes like tilapia, herring e. t. c. iii. Tube feet which enable them to hold on to rock shores and hard shell to prevent dessication e.g. starfish, whales.
  3. Whale has i. flippers for stability in water ii. An organ in front of the nostril for detecting pressure changes in water. iii. A thick layer of dermal fat insulation or food reservoir.
  4. Shrimps possess powerful claws for holding food or prey.
  5. Periwinkles possess lungs for breathing and foot for attachment.
  6. Crabs burrow fast into the mud to protect them against predators, strong waves or hide.


Adaptation of Plants to Marine Habitat 

Plants such as seaweeds, algae, and diatoms are naturally found in marine habitat with the following adaptive features;

  1. Seaweeds have i. hold–fast for attachment. ii. mucillagenous cover to prevent dessication. iii. Divided leaves or floating devices for buoyancy.
  2. Algae (e.g sargassum) have i. chlorophyll for photosynthesis. ii. Small size or large surface area for floating in water. 
  3. Planktons (e.g. diatoms) possess; i. air space in their tissues ii. Rhizoid for attachment to rocks iii. Air bladder for buoyancy (floating).


Plants Adaptation in Estuarine

Plants found in estuaries include planktons, algae, red and white mangrove. They have the following adaptive features; 

  1. Planktons (diatoms) have; i. air spaces in their tissues ii. rhizoid for the attachment to rock shores iii. air bladder for buoyancy
  2. Algae have: i. chlorophyll for photosynthesis ii. small size or large surface area for floating in water.
  3. Red mangrove has; i. stilt roots with rootlets that have air-spaces for air conduction to the root tissues and support to prevent washing away of the plant by the tide ii. Seeds which germinate while they are still on the parent plant, thus preventing the carrying away of the seedlings by water current.
  4. White mangrove has pneumatophores (breathing roots) for gaseous exchange.


Animal Adaptation 

Animals including mosquitoes, crustaceans, mollusks, worms, fishes e.t.c. found in estuaries ;survive possessing the following features;

  1. Mosquito larvae and pupae possess breathing trumpets for gaseous exchange
  2. Crustaceans and water snails burrow into the mud against predators, strong waves or tides.
  3. Worms have strong protective and impermeable covering against high salinity.
  4. Mudskippers have fins for crawling on land and swimming in water.
  5. Fishes have fins for movement and swimming bladder for buoyancy.



  1. What is a fresh water habitat?
  2. Mention five animals dwelling in estuary.


Plant Adaptation in Fresh Water 

Plants of fresh water include water lily, spirogyra, water lettuce, water weeds e.t.c. and they have the following adaptive features;

  1. Water lily has i. air bladder ii. expanded tips and light weight which keep it afloat.
  2. Spirogyra has mucillagenous cover for protection
  3. Water lettuce has hairs in leaves to trap air and keep it afloat
  4. Water weed (elodea) has a long and flexible petiole for swinging with water currents. 


Animal Adaptation 

Animals of fresh water habitats include protozoa, duck, pondskatters, hydra, fishes e.t.c. Their adaptive features include

  1. Protozoa have contractile vacuole for osmoregulation in water.
  2. Duck has webbed feet for locomotion and serrated beak for sieving food in water into its mouth. 
  3. Hydra has slippery surface, hooks and suckers for attachment to water particles.
  4. Pondskatters has long legs for skating on water surface.
  5. Fishes have swim bladders for buoyancy and gills for respiration.


General Evaluation 

  1. Using three plants and two animals, explain adaptation in marine habitats.
  2. Give two examples of food chain in marine habitats.
  3. Define an estuary.
  4. State four characteristics of an estuary.
  5. How do organisms adapt to life in estuary?


Weekend Assignment 

  1. Buoyancy in salt water is ensured by the following except  A. divided leaves  B. chlorophyll  C. floating devices  D. air bladder.
  2. The mucillagenous cover in sea weed and spirogyra is mainly for  A. protection  B. osmoregulation  C. avoiding dessication  D. feeding.
  3. Which of the following is not a fresh water habitat?  A. puddle  B. swamp  C. stream  D. sea.
  4. Which of these is not an adaptive feature in a marine habitat?  A. bladder for floating  B. hold fast for attachment  C. fur to prevent water loss  D. rhizoid for attachment to rocks.
  5. The following are characteristics of fresh water habitats except  A. low salt content  B. high salinity  C. shallow water  D. can be stagnant or running water.



  1. List five characteristics of an estuary.
  2. State five adaptive features of animals in a fresh water habitat and their functions.


Reading Assignment

 College Biology by idodo Umeh. Chapter 23, page 558-560


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