CLASS: SS 1

SUBJECT: BIOLOGY                          PERIODS: 3

DURATION:                                       45 MINUTES

TOPIC:              ADAPTATION   

SUBTOPIC 1:     STRUCTURAL ADAPTATION   

SUBTOPIC 2:     ADAPTIVE COLOURATION  

SUBTOPIC 3:     BEHAVIOURAL ADAPTATION

PREVIOUS KNOWLEDGE: STUDENTS AND FAMILIAR WITH THE

TOPIC

 

OBJECTIVES:    At The End Of The Period(s), students should be able to:

 

Period 1: Discuss the progressive change in anatomy of organisms from water to land

  1. Explain the term adaptive colouration and their functions

Period 2:    Explain the adaptation in form and function of living organisms due to environmental conditions

Period 3:    Discuss and state examples of structural adaptations in organizations that and their survival.

 

References: Essential Biology for senior secondary schools by M.C. Micheal by 499 – 510. Modern Biology for senior secondary schools 1 -3 pg 518 – 526, 144 – 147

 

CONTENT

Adaptation is a process by which an organism becomes filled to its environment, enabling it to live successfully and reproduce. Organisms undergo adaptation by developing special features which helps them to survive in their environment when their environment changes or if they migrate to a new environment. Organisms have features structural (morphological) and behavioural features or physiological which enables them to live successfully in a given habitat. The features that become changed or modified in the process and enable organisms to live well in a habitat are called adaptive features or adaptations. Variation, competition and natural selection play key roles in the adaptation of organisms for survival.

 

Adaptations are modifications in the form, structure, function and behaviour of organisms and it may be divided into

  1. Structural adaptations
  2. Adaptive colouration
  3. Behavioural adaptations

 

STRUCTURAL ADAPTATIONS

Almost every part of the body of a living organisms structurally adapted to its mode of life. Examples of these include

  1. Structural adaptation for obtaining food
  2. Toad – it has a long sticky tongue attached to the front end of the buccal cavity. It flicks out its tongue swiftly to catch fly. It possesses special olfactory organ in the head for perceiving of its food. Toad also possesses the ability to drag eyes in so that they make bulges in the roof of the mouth which prevents the prey from escaping or helping in swallowing.

 

  1. Spiny anteaters: has a long sticky tongue which is inserted into and ant termite nests and as well as spade their draws for digging into the ground.

Insects – they have mouth parts modified for various ways of feeding and in some insects, the legs are modified for various ways of feeding and in some insects, the legs are modified for catching and grasping prey examples include the following:

  1. Boring mouthparts: bore into plant parts and stored products destroying the tissue in the process e.g. weevil and their larvae
  2. piercing and sucking mouthparts – insects with strong mouthparts (proboscis) to pierce and suck e.g. mosquitoes, aphids, cotton strainers, mealy bugs, capsids / mixids, butterfly, housefly etc.

iii.      biting and chewing mouthparts – insects which possess strong mandible and maxillae e.g. cockroaches, grasshopper, locusts, termites etc.

 

  1. Birds:

Birds have special adaptive features for the habitat they live in to survive and obtain food e.g.

  1. Nectar suckers: Possess long hollow beaks with tubular longules for sucking e.g. sunbirds, woodpecker, humming birds.
  2. Filter feeders – possess beaks, adapted for gripping fishes and sieving out food e.g. ducks as well as webbed feet. Waders like ibis have long, narrow, curved beaks for probing for food.

iii.      carnivorous birds – possess strong and hooked beaks for killing and tearing flesh as well as sharp claws for catching and carrying prey e.g. hawks, eagles, owl etc.

  1. seed eaters – possess short, thick beaks, for cracking the hard covering of seeds or nuts e.g sparrows, weavers birds, parrots and even domestic fowl. Fowls possess strong feet with blunt claws for scratching the earth for worms, grains and seeds.

 

  1. Insectivorous plants – examples include utriculata species (bladderwort) and Drosera  species (sundew)
  2. Structural adaptation for protection: (escape and defense)

These features help the animals to escape, protect and defend themselves against the enemies. Examples are

  1. Scally anteater – it possess a horny armour and it rolls into a ball when attacked.
  2. Scorpions – use stings to attack prey and defend

iii.      Birds – possess wings with strong muscles to fly away.

  1. Snakes – use venom
  2. Bees and wasps – sting their enemies
  3. praying mantis; use its first pairs of legs which have sharp spines to defend itself and also to attack and kill insects for food.
  4. Toad – has shiny skin which possess mucous gland that prevents the load from being caught, keep the skin moist and from dying. Toads possess foul smelling chemicals, poisonous glands on the skin and a brownish colour which enable it to blend with its surroundings.

 

Toad has long hindlimbs with powerful muscles and no tail to help it move faster. Webbed hindlimbs (paddle) and a stream lined body for easy movement and swimming. The short forelimbs absorb shock on landing and for propping up the food end of the body.

 

iii.      Structural adaptation to attract mates: These special features enable them to attract males for the purpose of reproduction.

 

  1. Birds – Male birds e.g. domestic fowl, peacock etc possess striking features which they display with appropriate behavioural adaptations to attract females.
  2. Toad – possess nuptial ponds on their thumbs which help them hold the female firmly during mating
  3. Flowering plants – possess brightly coloured flowers to attract insects
  4. Agama Lizard: The male has bright colours which it displays by strutting to attract females for making.

 

  1. Structural adaptation to regulate body temperature

 

The ability of animals to regulate their body temperature can be divided into two namely hoiothermic which have constant body temperature (mammals and birds) and poikilothermic which doesn’t have constant body temperature but the temperature changes with the temperature of the environment (fishes, reptiles, amphibians). In homoithermic animals, structural features that are involved in regulating heat  loss include fat layer under the skin, body size and shape, skin covering hair (fur) and feathers, bare extremists of the body such as the inner surface of the pinna (external air) and the soles of feet.

 

The features in the table below are modified to reduce heat loss in cold regions and increase heat loss in hot regions.

 

 

 

Features

Hot regions

Cold regions

1

Fur

Sparse traps less air, not effective insulator

Thick; traps more air, very effective insulator

2

Fat layer under skin

Thin: not effective insulator

Thick; very effective insulator

3.

Body size and shape

Small and less bulky: greater surface area in relation to body volume, thus enhancing heat loss from the body

Large and bulky: smaller surface area in relation to body volume, thus reducing heat loss from the body

4

Ears and feet

Large greater surface area which enhances heat loss from the body

Small: smaller surface area which reduces heat loss from the body.

 

 

 

 

 

  1. Structural adaptation for water conservation

Based on water availability, plants can be divided into

  1. Hydrophytes – Plants that live in water e.g. water hyacinth and water lily. All or part of ther body is in water. The roots and xylem are poorly developed while the exposed parts are covered with thick cuticle or prevent water loss. Large well developed air spaces provide a supply of oxygen to the underwater parts and helps the plant to be buoyant.

         

  1. Mesophytes – are land plants found in places where adequate water supply is present. They have well developed root and shoot systems. A waxy cuticle covers the body surface to minimize water loss e.g. Hibiscus and cassava

 

  1. Xerophytes – are plants that can survive where water supply is scarce e.g. deserts. The roots are well developed (grow down to great depths and branch extensively) some have swollen stems or leaves containing water storage cells (called succulents e.g. cacti, aloe, euphorbia) some have spiny leaves, the protoplasm in the cells can tolerate a high degree of water loss without being damaged etc.

In animals, possession of scales (snakes, lizards) possession of shell (snail), exoskeleton (cockroach and grasshopper) feathers (birds) and hairs to reduce water loss and evaporation.

 

ADAPTIVE COLOURATION

This is the process of a colour by an organisms which enable it to catch its prey, avoids its predators or enemies and ensures its survival. Adaptive colouration is due to the presence of pigments in cells.

 

 

Pigments

Colour

Distribution

1

Chlorophyll

Green

Mainly in chloroplasts of plant cells

2

Melanin

Yellow to black

Mainly in animal cells (melanophores) beneath the epidermis, gives colour to the skin, hair and the ink in cuttlefish. 

3

Carotene and xantophyll

Yellow to orange

Found in chromoplasts in plants cells and chromatophores (pigment cells) in animals

4.

Anthocyanins

Red, blue and violet

Mainly in cell sap of flowers, fruits, leaves and stem.

                               

Adaptive colouration may be divided into:

  1. warning coloration: This announces the presence and scares any enemies or predators, indicating the animal is unpalatable or possess unpleasant features e.g. yellow and black stripes of yellow jackets and other wasps (sting) colorful spotted makings of lady bird beetles (foul tasting), vivid orange and green pattern of south American forest frogs (whose skin has newomuscular poison) striking white stripes on the bodies of stripped polecasts and skinless (which spray foul smelling liquids)

 

  1. Concealing / cryptic colouration or camouflage – The colour matches the colour of the background. It helps the prey protective colouration and the predator remain unnoticed e.g. green snake, green cuticle of the grasshopper and the white coat of the Arctic fox, geck.

 

  1. Disruptive colouration: These are patterns on the body which break up the familiar body shapes against the light and dark shades of their background enabling them tog o undetected e.g. spots and stripes of the leopard, giraffe, zebra, tiger, etc.

 

  1. Counter shading: This is the possession of dark coloured dorsal surface and light coloured ventral surface which makes a prey (fish) go unnoticed by a predatory bird from the top because it blends with its shadow and the dark waters underneath it and below by a predatory fish because it merges with the light falling from above.

 

  1. Mimicry: This is a condition in which a harmless organisms resembles a harmful or distasteful one so that its enemies would avoid it (Batresian mimics) Colour and colour patterns are used extensively by mimics. Mullerian mimics resemble each other closely by similarly colouring and patterns on their bodies e.g. the foul tasting Acraea butterfly and the poisonous African monarch. Swallow tail butterfly has red colouration on the wing like a distasteful one, wasp with its paint sting and the harmless flower fly (Batesian), stick insect which resembles dead twigs, the katedkd a grasshopper which mimics a living leaf.

 

  1. Mating colouration: Conspicuous skin colouration in adult males help the adult females to select males of their own species for mating.

 

  1. Colour change: Certain animals change the colour of their body  surfaces to match their environment and escape detection. These animals contain special pigment cells (chromatophores) on their body surfaces which are involved in colouration and colour changes. The colour changes are brought about by the nervous system or the hormonal system or both and its is initiated (stimulus) by the light entering the eyes e.g. chameleon and some grasshoppers.

 

BEHAVIOURAL ADAPTATION

Plants and animals exhibit a variety of behaviour patterns with respect to obtaining to obtaining food, escape and defense, surviving unfavourable conditions, communication, finding mates and caring for the young.

 

Adaptive colouration in plants

  1. Pollination: insect pollinated flowers are brightly coloured to attract insects.
  2. Feeding: Some insectivorous plants e.g. nepenthes and sarania have brightly coloured pitchers to attract insects that may fall into the pitches, drain in the liquid in them and get digested.

 

  1. BEHAVIOURAL ADAPTATION TO OBTAIN FOOD

These type of behaviours are called foraging behaviours and it is exhibited in different ways such as setting a trap e.g. ant lion which digs a funnel shaped hope and lies partly hidden at the bottom to catch its prey (ants) and spider which spins a web, overtaking its prey by speed e.g. cheetaband lion, lying in search e.g. oyster catche, lure e.g. angler fish

 

  1. Behavioural adaptation for escape and defense
  2. Scaring, startle, confuse or distract predators
  3. Hiding
  4. Remaining motionless e.g. opossum millipede
  5. Swaying in the air e.g. bat
  6. Secretion of irritating liquid e.g. toad, skunk
  7. overrun/fly away e.g. gazelles, antelope, impale
  8. secretion of offensive odour e.g. beetles, birds
  9. Puffing up e.g. toad, porcupine fish
  10. Erratic movement e.g. butterfly
  11. Rolling into a ball e.g. hedgehog
  12. Shedding body parts e.g wall gecko / house lizard which sheds its tail when gripped by a predator.
  13. Fighting off enemies e.g. hawk (which falls on its back and lash out with its tailous and beaks) and buffalo.
  14. Sham aggressive behaviour e.g. frilled lizard by expanding a frill around its neck, open its mouth wide and hissing to look fierce.
  15. Secretion of ink or coloured substances to impair vision e.g. squid, octopus
  16. Secretion of stings / injections / painful chemicals e.g. bees, wasps, scorpions, electric fish.

iii.      Behavioural adaptation for surviving unfavourable conditions.

 

 Animals exhibit definite behavioural patterns to tide our unfavourable environmental conditions such as high or low temperatures, food and water shortage. These behaviours include the following;

  1. Hibernation: This is a condition in which an animal intemperate zones pass through water or when food is scarce in a sleep like inactive, torpid condition in which their metabolism and body temperature are very low. Such animals store large amounts of fat in their body before winter and retreat to safe places where they burn off the fat slowly. Examples including woodchucks, ground squirrels, polar bears. Insects eating bats wake and feed on warm days.
  2. Aestivation: This is similar in a way to hibernation but takes place in the hot dry season. It is a period of inactivity (sleep like torpid state) observed in certain animals during long periods of heat and drought. E.g. African lung fish, crocodile, some insects, snakes, toads and rodents.
  3. Migration: These are long journeys that animals make from one place to another, it may be seasonal or in pursuit of more favourable environmental conditions, avoid overcrowding, in search of mates and to establish new habitats e.g. cattle egrets migration from the North to South during the dry and rainy seasons.

 

Other examples includes agama lizards basking in the early morning sun to absorb eat  and move into the shade, desert animals are active atnight and sleep during the day, penguins huddle together in large numbers to keep warm.

 

  1. Behavioural adaptation for communication.

 

Animals exhibit various behaviours that enable them to communicate with other members of their species or communities.

  1. Communication by sound and contact
  2. In times of hunger – to get attention e.g. goat bleating, mother hen calling the chicks.
  3. Danger: a member of the group alerts others to danger e.g. mother hen, birds at the sight of a hawk, a guard dog bases its teeth, snarls and bristles, slapping sound of a beaver tail on water at the sight of danger.
  4. Parental care e.g. Mother hen, female scorpion carries her young on her back until their first moulting, male sea horse, carries the eggs in his pouch until they hatch.
  5. Reproduction: to attract the opposite sex e.g. croacking of a male toad.
  6. Communication: by touch e.g. worker bee (waggling dance) to show direction and distance of food source.
  7. Communication by touch e.g ants in a colony touch to recognize members of the same colony, male spider strumming female spider’s silk thread (web) to alert her of its presence.
  8. Communication by sense of smell e.g. antelope ribs a gland on its forehead on a twig of plants to mark its territory, dogs, hyenas etc .

 

Some animals exhibit gregarious behaviour, that is, the animals of the same species move together in a group which give them survival advantage. Examples of such animals include gazelles, zebra, impalas, elephants, some flocks of birds, some shoals of fish, some social animals like termites, bees, wolves, foxes and baboons.

 

  1. Behavioural adaptation in plants
  2. Phototropic movements of plants shoots
  3. Coiling response of leaf tendrils of the Gloriosa plant when they touch a support
  4. Carnivorous plants (venus flytrap)
  5. shedding of leaves which enable them survive harsh weather conditions especially during dry season to reduce water loss e.g. silk cotton, book.

5       Vegetative part death – some plants die and survive the dry season as underground stem e.g. yam, potatoes, stubborn grass.

 

INSTRUCTIONAL MATERIALS: Pictures and videos showing organisms in their natural habitats.

TEACHING METHODS PROCEDURES

Step I: Teacher revises the previous topics and introduce the new topic

Step II: Teacher introduces by defining adaptation and explains the types of adaptation

Step III: Teacher explains behavioural adaptations in both plants and animals.

Step IV: Teacher allows students to ask questions and write notes under content on the board.

 

Classwork(activities)

Period 1: Students discuss adaption with examples

Period 2: Students discuss adaptive colouration in living organisms

Period 3: Students discuss  behavioural adaptation in living organisms.

 

EVALUATION

Period 1:

  1. Define adaptation
  2. What do you understand by competition

Period 2:

  1. What is adaptive colouration
  2. Mention the types of adaptive coloruation

 

Period 3:

What is gregarious behaviour

 

SUMMARY/CONCLUSION:

Teacher summarises the topic, marks the students notes and makes corrections where necessary

 

ASSIGNMENT(S)

Period 1: state the adaptation of tapeworm (Taenia   solium  to its habitat in the human gut.

Period 2: Describe six protective adaptations used by animals against predations and give one example in each case

Period 3: Discuss the structural adaptation to regulate body temperature in

  1. Mammals
  2. Birds.