Adaptations — Structural, Behavioural, Physiological
In 2021, CSIRO researchers filmed thorny devil lizards channelling dew along skin grooves to their mouth — absorbing up to 5 mL of water in just 30 seconds, a structural adaptation to Australia's driest deserts.
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Q1 · A koala has sharp claws and a stubby thumb that work brilliantly for gripping smooth gum trees. Where do you think this useful feature came from?
Q2 · Two animals — a polar bear and a camel — both survive in extreme places (very cold; very hot/dry). Write one feature you think each animal has to cope with its environment.
● Know
- The definition of an adaptation as an inherited feature
- The three types: structural, behavioural, physiological
- At least two Australian examples of each type
● Understand
- Why adaptations help an organism survive in its specific environment
- Why adaptations evolve over many generations, not in a single life
- The difference between an adaptation and a learned skill
● Can do
- Sort an animal's features into structural, behavioural or physiological
- Explain how an adaptation suits an animal's environment
- Justify why "use it or lose it" muscle gain is NOT an adaptation
- Adaptation
- Structural
- Behavioural
- Physiological
- Inherited
- Inherited pattern of action (e.g. migration)
- Passed from parent to offspring through genes
- Inherited feature that helps survival
- Internal body-process adaptation
- A body part you can see or touch
Look at a koala sitting in a gum tree and notice its feet: two opposable thumbs on each front paw grip the smooth vertical bark without slipping — that is a structural adaptation you can point to and measure. If you can point to it, draw it, or measure it, it's almost certainly structural.
| Australian example | Structural feature | How it helps |
|---|---|---|
| Koala | Two opposable thumbs and rough paw pads | Lets it grip smooth gum bark for hours without slipping. |
| Frill-neck lizard | Large skin frill around the neck | Flared out, the frill makes the lizard look much bigger to scare off predators. |
| Echidna | Long sharp spines made of keratin | Predators that bite get a mouthful of spines — protective armour. |
| Kangaroo | Huge powerful back legs and stiff tail | Hopping uses less energy than running for long distances across dry country. |
| Sugar glider | Patagium — a stretchy skin flap between front and back legs | Lets the animal glide between trees instead of climbing down and crossing the ground (where predators wait). |
Structural adaptations are the easiest type to spot because they are visible. Most early biologists studied these first.
A behavioural adaptation is an inherited action — something the animal does. You can't take a photo of the behaviour by itself; you have to watch the animal moving over time.
- Kangaroos lick their forearms when it's hot — saliva evaporates and cools the blood flowing under the thin skin (their version of sweating).
- Migratory birds like the bar-tailed godwit fly thousands of kilometres each year from Alaska to NSW to chase food and warmth.
- Bogong moths migrate up into the Australian Alps each summer to escape the heat.
- Tasmanian devils are mostly nocturnal — they hunt at night to avoid the hot sun and reduce competition with daytime predators.
- Meerkats (not Australian, but a classic) take turns standing as lookouts — inherited social behaviour.
Important: these behaviours are inherited, not learned. A baby kangaroo doesn't watch its mum and copy the licking — the wiring is built in.
A physiological adaptation is an inherited internal body process. You can't see it from the outside — it usually involves chemicals, cells, organs or blood working in a special way.
| Animal | Physiological adaptation | How it helps |
|---|---|---|
| Camel | Red blood cells that survive losing up to a third of their water | Lets the camel keep going for days without drinking in the desert. |
| Echidna | Lower body temperature and slow metabolism | Helps it survive cool nights and reduces food needs. |
| Brown snake | Highly toxic venom produced in special glands | Kills or paralyses prey quickly so the snake doesn't get bitten back. |
| Bogong moth | Stored body fat used as fuel for long migration | The moth can fly hundreds of kilometres without eating. |
| Hibernating mammals | Heart rate and metabolism drop dramatically in winter | Uses very little energy when food is scarce. |
A handy test: if the feature only shows up when you look inside the animal (blood, glands, chemistry), it's physiological.
The three types of adaptation are (body parts), (inherited actions) and (internal processes). Adaptations are , not learned.
Wrong: "Bodybuilders pass their big muscles on to their kids." Lifting weights changes your body during your life — but those changes happen in your muscle cells, not your sex cells. Your children inherit your genes, not your training.
Right: An adaptation has to be inherited. Changes you cause in your own body by exercise or injury are not passed to offspring.
Wrong: "Giraffes got long necks because they stretched up over many lifetimes." Each giraffe doesn't make its own neck longer. The animals born with slightly longer necks were better fed, survived more, and had more offspring with long necks. Over many generations the average neck length increased.
Right: Adaptations evolve over many generations, through small inherited differences and survival, not through one animal's effort.
Wrong: "My dog learned to sit when I say sit — so that's a behavioural adaptation." Learning a trick is not the same as a behavioural adaptation. Adaptations are inherited and present in every member of the species.
Right: A behavioural adaptation is built in (inherited). A trained behaviour is learned in one individual's life and dies with that individual.
Most animals show all three types of adaptation at the same time. The camel is a classic example because it lives in a brutal environment (hot, dry desert).
- Structural: wide flat feet that don't sink in sand; long eyelashes that block sand; humps that store fat (not water — that's a myth).
- Behavioural: sits with its legs tucked under to keep its belly off the hot sand; moves slowly in the middle of the day.
- Physiological: red blood cells that can lose up to ⅓ of their water without bursting; concentrated urine; tolerates very high body temperatures so it doesn't have to sweat as much.
Take any one of these away and the camel survives less well. Together they make it one of the most desert-adapted mammals on Earth.
Imagine moving a polar bear (white fur, thick blubber, big paws for snow) to outback Australia. Predict: would its adaptations still help it survive? Explain in one or two sentences, then reveal.
How close was your prediction?
Great — you spotted that "good adaptation" depends on the environment.
Good — being surprised is the point. Adaptations are environment-specific.
Earlier you were asked: A bodybuilder trains for 20 years and gets huge arms. Their child is born small and skinny. Why didn't the muscles "get passed on"?
Now answer it fully using the words inherited, genes and adaptation.
Q1. Define the three types of adaptation and give one Australian example of each. (3 marks)
Q2. A frill-neck lizard flares its huge skin frill when a predator approaches. Identify the type of adaptation, and explain how it helps the lizard survive. Then suggest one structural feature of the lizard that supports this behaviour. (4 marks)
Q3. A student says: "If I spend my whole life in the snow, my kids will be born with thick fur." Evaluate this claim using the proper definition of an adaptation and explain how real adaptations actually appear in a species. (4 marks)
Answers
▾MCQ 1
C — An adaptation is an inherited feature that helps an organism survive. A is wrong (learning isn't inherited). B is wrong (exercise changes don't pass on). D is wrong (an adaptation isn't a choice).
MCQ 2
A — Spines are a visible body part, so they are structural. (Don't confuse this with the chemical processes inside the body, which would be physiological.)
MCQ 3
D — The camel's blood cells doing something special internally is physiological. You can't see it from outside the camel.
MCQ 4
B — Exercise changes muscle cells but not the sex cells whose genes are passed to children. Adaptations have to be inherited.
MCQ 5
B — Licking is an inherited action (the wiring is built in), so it's behavioural. The cooling effect that follows is physiological, but the licking itself is a behaviour.
Short Answer 1
Model answer: Structural = visible body part — example: koala's gripping paws / echidna's spines. Behavioural = inherited action — example: kangaroo licking its forearms to cool / bogong moth migration. Physiological = internal body process — example: brown snake venom / camel's tough red blood cells.
Short Answer 2
Model answer: Frill flaring is a behavioural adaptation. When threatened, the lizard suddenly displays a huge collar, which makes it look much bigger and more dangerous than it is, scaring predators away long enough for the lizard to escape. The behaviour is supported by the structural adaptation of the large frill of loose skin around the neck — without that body part the behaviour wouldn't work. Many adaptations work in pairs like this.
Short Answer 3
Model answer: The claim is incorrect because adaptations must be inherited through genes, and changes you cause to your own body during your life (like growing thicker hair from cold) do not change the genes you pass on. Real adaptations appear gradually in a species over many generations: individuals born with slightly thicker fur survive cold weather better, so they live longer and have more offspring with the same trait. Over hundreds of generations the average fur thickness of the population increases. So one person living in snow doesn't change their children — but a whole species living in snow for thousands of generations can gradually become better suited to it.