Animals & Nature · Unit 10
Fish and Ocean Life
Fish, sharks, reefs and the deep sea
The ocean is the largest habitat on the planet by a wide margin, and most of it is dark, cold and under enormous pressure.
The unit covers what makes a fish, sharks and rays as a separate lineage with skeletons of cartilage, coral reefs, the ocean zones and the plankton that feed nearly everything, and the deep sea.
This unit breaks down into 18 short steps and 108 questions, starting at difficulty 2 and building to 3. Below you can see exactly what it covers, how the path is structured, and worked examples with explanations.
- Steps
- 18
- Questions
- 108
- Difficulty
- 2-3
What this unit covers
- What Makes a Fish
- Sharks and Rays
- Coral Reefs
- Ocean Zones and Plankton
- The Deep Sea
Where this fits
Follows Animal Groups. Connects to Geography's Coasts and Oceans.
Where people slip
Coral is an animal, not a plant or a rock. Reefs are colonies of tiny animals living with photosynthetic algae, which is why bleaching happens when the partnership breaks down.
How the unit is structured
Fish and Ocean Life runs as 18 short steps that unlock in order. 13 are practice rounds and 5 are challenge rounds that pull together everything before them. Questions start at difficulty 2 and climb to 3 as you progress.
Challenge rounds
Example questions
30 real questions from this unit, with the answer and the reason behind it, grouped by what they practise. There are 108 in the unit altogether.
Coral Reefs
- Choose all that applyLevel 2
1. Which harm coral reefs? Pick all that apply.
- Warming ocean temperaturescorrect
- Pollution running off the landcorrect
- Destructive fishingcorrect
- Clean cool water
Warming seas, pollution and damaging fishing all harm reefs.
- Multiple choiceLevel 2
2. What are coral reefs built by?
- Tiny animals called polypscorrect
- Fish building nests
- Volcanoes only
- Seaweed
Tiny animals called coral polyps build stony skeletons over thousands of years.
- True or falseLevel 2
3. The Great Barrier Reef is the largest coral reef system in the world.
Answer: True
True. It stretches for over two thousand kilometres along Australia.
- Type the answerLevel 2
4. Which country's coast has the Great Barrier Reef?
Answer: Australia
It lies off the coast of Queensland, Australia.
- Multiple choiceLevel 2
5. Why are coral reefs sometimes called the rainforests of the sea?
- They hold huge numbers of speciescorrect
- They are made of wood
- They are always green
- They grow above water
They hold an enormous variety of life in a small area.
- Choose all that applyLevel 3
6. Which factors influence reef recovery? Pick all that apply.
- Water qualitycorrect
- Healthy grazing fish populationscorrect
- Time between disturbancescorrect
- The number of tourists photographing them
Water quality, fish populations, time between bleaching events and connectivity all matter.
Ocean Zones and Plankton
- Multiple choiceLevel 2
7. What is diel vertical migration?
- Animals rising at night and sinking by daycorrect
- Whales swimming to the poles
- Fish moving between rivers and sea
- Birds flying south
Vast numbers of small animals rise at night and sink by day, the largest daily migration on Earth.
- Put in orderLevel 2
8. Put the ocean layers in order from surface to deepest.
Answer: Sunlight zone -> Twilight zone -> Midnight zone -> Deep trenches
Sunlight, twilight, midnight, then the trenches.
- Sort into groupsLevel 2
9. Sort each animal by the ocean zone it mainly lives in.
Answer: Coral reef fish = Sunlit shallows; Sea turtle = Sunlit shallows; Anglerfish = Deep sea; Tube worm at a vent = Deep sea
Different zones support very different communities.
- Build the sentenceLevel 3
10. Build a sentence about ocean science.
Answer: Much of the deep ocean is unexplored
Much of the deep ocean is still unexplored.
- Choose all that applyLevel 3
11. Which threaten ocean life today? Pick all that apply.
- Overfishingcorrect
- Plastic pollutioncorrect
- Warming and acidificationcorrect
- Marine protected areas
Overfishing, plastic, warming and acidification are all major pressures.
- Fact or fibLevel 3
12. The ocean has absorbed a large share of the extra heat and carbon from human activity.
Answer: True
True, which has slowed surface warming but changed the ocean itself.
Sharks and Rays
- Choose all that applyLevel 2
13. Which are true of sharks? Pick all that apply.
- They have cartilage skeletonscorrect
- They replace teeth throughout lifecorrect
- They have excellent sensescorrect
- They breathe air with lungs
Cartilage skeletons, replaceable teeth and keen senses all apply.
- Multiple choiceLevel 2
14. What are shark skeletons made of?
- Cartilagecorrect
- Bone
- Shell
- Muscle only
Sharks have flexible cartilage instead of bone.
- Picture questionLevel 2
15. 🦈 Which animal group does this belong to?
- Fishcorrect
- Mammals
- Reptiles
- Amphibians
Sharks are fish, with cartilage skeletons.
- True or falseLevel 2
16. The whale shark is the largest fish in the world.
Answer: True
True, and it feeds by filtering tiny plankton.
- Type the answerLevel 2
17. Which enormous shark feeds by filtering plankton from the water?
Answer: whale shark
The whale shark is a harmless giant.
- Choose all that applyLevel 3
18. Which are important shark senses? Pick all that apply.
- An acute sense of smellcorrect
- Electroreceptioncorrect
- The lateral linecorrect
- Echolocation
Smell, electroreception and the lateral line all help sharks hunt.
The Deep Sea
- Choose all that applyLevel 2
19. Which are challenges of deep-sea life? Pick all that apply.
- Total darknesscorrect
- Crushing pressurecorrect
- Very little foodcorrect
- Too much sunlight
Darkness, cold, pressure and scarce food all define the deep.
- Multiple choiceLevel 2
20. What is bioluminescence?
- Light produced by living thingscorrect
- Light from the moon
- Glowing rocks
- Reflection from scales
It is light made by living things, common in the deep sea.
- True or falseLevel 2
21. Some deep-sea fish use a glowing lure to attract prey.
Answer: True
True. Anglerfish dangle a light in front of their mouths.
- Type the answerLevel 2
22. Which deep-sea fish uses a glowing lure on its head to attract prey?
Answer: anglerfish
The anglerfish waits in the dark with its light shining.
- Multiple choiceLevel 2
23. Why is the deep sea completely dark?
- Sunlight cannot reach that deepcorrect
- The water is black
- There is no sun at night
- Fish block the light
Sunlight cannot reach beyond a few hundred metres of water.
- Choose all that applyLevel 3
24. Which discoveries came from deep-sea exploration? Pick all that apply.
- Hydrothermal vent communitiescorrect
- Whale fall ecosystemscorrect
- Many new speciescorrect
- Freshwater lakes on the sea floor with no salt at all
Vent ecosystems, whale falls and countless new species were all found there.
What Makes a Fish
- Choose all that applyLevel 2
25. Which are features of most fish? Pick all that apply.
- Gillscorrect
- Finscorrect
- Scalescorrect
- Lungs
Gills, fins and scales are the classic fish features.
- Fill the blankLevel 2
26. A line of sense organs along a fish's side, feeling movement in the water, is the lateral ____.
- linecorrect
- fin
- scale
- gill
The lateral line detects vibrations and currents.
- Multiple choiceLevel 2
27. Why do many fish swim in large groups called schools?
- It confuses predatorscorrect
- It makes them swim faster individually
- It keeps them warm
- It helps them breathe
A school confuses predators and makes it harder to single out one fish.
- True or falseLevel 2
28. Many fish have a gas-filled swim bladder that helps them float at the right depth.
Answer: True
True. Adjusting the gas changes how buoyant they are.
- Type the answerLevel 2
29. What is the gas-filled organ that helps a fish stay at a chosen depth called?
Answer: swim bladder
The swim bladder acts like an internal float.
- Choose all that applyLevel 2
30. Which are true of some fish? Pick all that apply.
- Some can change sexcorrect
- Some produce their own lightcorrect
- Some can breathe aircorrect
- Some have feathers
Some change sex, some produce light and some can breathe air.
Where these questions come from. Each unit starts as a plan of the concepts it should cover and the difficulty it should span. Questions are written against that plan with AI assistance, then checked by a validator that rejects anything without a single defensible answer, an explanation, or plausible wrong options. How we write questions sets out the whole process, and corrections are fixed in the bank and reach the site and the app the same day.
How you practise
This unit mixes 10 different question formats, so you are recalling and applying rather than recognising the same layout every time.
- Build the sentence
- Choose all that apply
- Fact or fib
- Fill the blank
- Multiple choice
- Picture question
- Put in order
- Sort into groups
- True or false
- Type the answer
Practise Fish and Ocean Life
108 questions across 18 steps. Start with step one and crawl at your own pace.
Play this unitRead about Fish and Ocean Life
Explainers from our blog on what this unit covers. Each one ends with real questions from the bank.
- How Do Fish Breathe Underwater?How gills pull oxygen from water, why the countercurrent system is so efficient, and how some fish breathe air.August 28, 2026 · 5 min read
- How Coral Reefs Grow and Shape CoastsCoral reefs are built by colonies of tiny animals that deposit calcium carbonate. Warm, shallow and clear water supports reef growth, while the reef changes waves, sediment and coastal habitats.July 29, 2026 · 5 min read
More units in Animals & Nature
- What Is an Animal?What makes something an animal, and what every animal needs
- Pets and Farm AnimalsThe animals we live and work with, and how to care for them
- Animal GroupsMammals, birds, reptiles, amphibians, fish and creatures without backbones
- Habitats and HomesWhere animals live, from rainforest to polar ice, and the homes they build
- Baby Animals and FamiliesEggs and live young, animal parents, and growing up
- What Animals EatDiets, teeth, hunting, and how energy flows through a food chain
- MammalsFur, milk and warm blood, from bats and whales to big cats
- BirdsFeathers, beaks, flight and song across the bird world