Adaptation – SS3 Biology Lesson Note (Second Term)

Adaptation is the possession of structural, physiological or behavioural features that help an organism to survive in its environment.

Behavioural objectives

By the end of the lesson, students should be able to:

1. define adaptive colouration and describe its types with examples;
2. describe behavioural adaptation in predators, prey, plants and animals facing harsh weather;
3. define aestivation, hibernation and gregarious behaviour;
4. define social animals and state the characteristics of social insects;
5. describe the castes, life history and economic importance of termites;
6. describe the castes and economic importance of honey bees.

What is adaptive colouration?

Adaptive colouration is the possession of a body colour that helps an organism to catch prey, avoid enemies, secure mates and survive.

What are the types of adaptive colouration?

There are six types of adaptive colouration: concealing, disruptive, warning, mating, mimicry and bright colouration.

• Concealing (cryptic) colouration: helps organisms blend with their background so that predators do not notice them.
• Disruptive colouration: uses patterns to break up the body outline against the dark and light shades of the background, as in giraffes, leopards, tigers and ladybird beetles.
• Warning colouration: announces the organism to predators so that they avoid it, because it tastes bad or is harmful, as in variegated grasshoppers and the black and yellow bands of wasps.
• Mating colouration: helps to attract a mate, as in the male agama lizard and the peacock.
• Mimicry: a harmless organism looks like a distasteful or harmful one, so enemies avoid it, as in swallowtail butterflies and stick insects.
• Bright colouration: attracts animals, as in insect-pollinated flowers and the pitchers of insectivorous plants.

What are the forms of concealing colouration?

Concealing colouration takes three forms: colour blending, countershading and colour change.

• Colour blending: the body colour matches the surroundings, as in the green cuticle of grasshoppers and green snakes.
• Countershading: the upper (dorsal) surface is dark and the lower (ventral) surface is light, so the animal is hard to see from above and below, as in tilapia fish.
• Colour change (camouflage): the animal changes colour to match its surroundings, as in the chameleon.

What is behavioural adaptation?

Behavioural adaptation is any action of an organism that helps it to survive.

There are five main kinds: in predators, in prey, against harsh weather, in plants and gregarious behaviour.

How do predators adapt in behaviour?

• Lion: chases its prey at high speed.
• Spider: spins webs to trap its prey.

How does prey adapt in behaviour?

• Bats: hang upside down from tree branches.
• Antelopes: escape from predators by running fast.
• Beetles: release an offensive smell.
• Toads: puff up their bodies.

How do animals adapt to harsh weather?

Animals avoid harsh weather by aestivation, hibernation or migration.

• Aestivation: a long period of inactivity (dormancy) during the hot, dry season, as in the African lungfish and snails.
• Hibernation: a long sleep during cold weather or food scarcity, as in insect-eating bats.
• Migration: the movement of animals to a more favourable habitat, as in cattle egrets.

What is the difference between aestivation and hibernation?

Aestivation is dormancy to survive heat and drought. Hibernation is dormancy to survive cold and food scarcity.

How do plants adapt in behaviour?

• Leaf shedding: deciduous plants drop their leaves in the dry season to reduce water loss.
• Underground stems: yam and potato tubers survive underground after the shoots die down.
• Dormant seeds: seeds stay inactive until conditions are suitable for germination.
• Positive phototropism: plant shoots grow towards light.

What is gregarious behaviour?

Gregarious behaviour is the habit of living or moving in groups.

• Examples: elephants, zebras, birds, fishes and social insects such as bees and termites.

What are social animals?

Social animals are animals of the same species that live together and cooperate in organised communities called societies or colonies.

• Social insects: termites, honey bees, wasps and ants.
• Social mammals: wolves, foxes and baboons.

What are the characteristics of social insects?

• Group living: the members live together.
• Division of labour: each group of members does a particular job.
• Castes: the members belong to distinct groups with different forms and duties.
• Communication: members pass information to one another within the colony.

Termites

Where do termites live?

Termites live in large communities in nests, which may be tunnels in dead wood or anthills (termitaria).

• Sight: workers and soldiers are blind.
• Communication: termites communicate by touch and smell.

What are the castes of termites?

Termites have three castes: the reproductives, the soldiers and the workers.

Reproductives

The reproductives are the fertile members, and they are of three types: king, queen and winged reproductives.

• King: wingless, smaller than the queen, and fertilises the queen.
• Queen: has a small head, a small thorax and a very large abdomen, and is the largest caste. Only one queen is found in a colony at a time, and she lays the eggs.
• Winged reproductives: fertile members that can become kings and queens of new colonies.

Soldiers

Soldiers defend the colony against enemies.

• Features: sterile, wingless and blind, with big heads and hard mandibles.
• Mandibulate soldiers: have strong mandibles.
• Nasute soldiers: have projecting mouthparts.

Workers

Workers are the most numerous caste and do most of the work of the colony.

• Features: wingless, blind and sterile, with well-developed mouthparts.
• Building: they build and repair the termitarium.
• Feeding: they provide food for all members and feed the queen and the nymphs.
• Brood care: they look after the eggs laid by the queen and the young termites (nymphs).
• Fungus gardens: in some species, they grow fungus for food.

What is the life history of termites?

Termites undergo incomplete metamorphosis, which has three stages.

1. Egg: laid by the queen.
2. Nymph: hatches from the egg and looks like a small adult.
3. Adult: the nymph grows into a reproductive, a soldier or a worker.

• Nuptial flight: mature winged reproductives swarm out of the colony to start new colonies.

How are termites adapted for survival?

• Group movement: they move in groups to ward off enemies.
• Varied diet: they feed on both living and dead plant material.
• Burrowing: they build tunnels in soil or wood for protection.
• Feeding on dead members: this keeps the colony clean.
• High reproduction: the queen lays many eggs, which keeps the colony large.

What is the economic importance of termites?

Termites are useful in some ways and harmful in others.

• Soil mixing: their tunnelling loosens and mixes the soil.
• Decomposition: they break down wood and add humus to the soil.
• Food: they are a good source of protein and fat.
• Anthill clay: it is used to make the surface of tennis courts.
• Damage: they destroy wooden buildings, furniture and crops.

Honey bees

Where do honey bees live?

Honey bees are social insects that live in hives made up of chambers or cells.

What are the castes of honey bees?

A honey bee colony has three castes: the drone, the queen and the workers.

What do worker bees do?

• Collecting food: modified mouthparts collect nectar, and modified legs collect pollen grains.
• Tail wagging: a special dance that tells other workers where a food source is.
• Hive building: they secrete wax and use it to build the hive.
• Hive care: they ventilate the hive, clean the cells and guard the hive.
• Honey making: they make honey from nectar.
• Feeding the young: they feed the larvae with royal jelly or honey.

What is the economic importance of honey bees?

• Pollination: they pollinate flowers.
• Honey: it has high nutritive and medicinal value.
• Beeswax: the wax from the hive is used to make candles and polish.

Evaluation

1. Name the six types of adaptive colouration and give one example of each.
2. Differentiate between aestivation and hibernation.
3. State four characteristics of social insects.
4. Name the three castes of termites and state one function of each.
5. What is tail wagging in a beehive, and which caste performs it?

Assignment

Draw a table showing the castes of (a) a termitarium and (b) a beehive, with one role for each caste.