What is the largest ocean in the world?
Answer : The Pacific
The Pacific is the largest and deepest ocean.
Questions and answers: Oceans & Marine Life
Revise Oceans & Marine Life: here is a selection of questions of every level, with the answer and an explanation. To test yourself without seeing the answers, play the quizzes.
Play the Oceans & Marine Life quizzesVery easy
What is the largest animal on the planet?
Answer : The blue whale
The blue whale is the largest known animal.
How many arms does an octopus have?
Answer : Eight
An octopus has eight arms.
Where does the clownfish live?
Answer : A sea anemone
The clownfish shelters among the tentacles of an anemone.
The dolphin is...
Answer : A mammal
The dolphin is a marine mammal that breathes air.
Where do sea turtles lay their eggs?
Answer : On beaches
Females come ashore to lay eggs in beach sand.
Which sea animal has a shell and claws?
Answer : The crab
The crab has a hard shell and two claws.
Ocean water is...
Answer : Salty
Ocean water contains dissolved salts, mainly common salt.
Easy
Which animals build coral reefs?
Answer : Coral polyps
Polyps secrete the limestone that forms reefs.
What does a jellyfish have instead of a brain?
Answer : A diffuse nerve net
Jellyfish have no brain, only a nerve net.
Through what opening does a whale breathe?
Answer : The blowhole
Whales breathe air through a blowhole on top of the head.
What does the blue whale mainly eat?
Answer : Krill
The blue whale filters krill, tiny crustaceans.
What is the deepest known ocean trench?
Answer : The Mariana Trench
The Mariana Trench reaches nearly 11,000 m.
Which of these animals is NOT a fish?
Answer : The jellyfish
The jellyfish is a cnidarian, not a fish.
To which family does the orca belong?
Answer : Dolphins
The orca is the largest member of the dolphin family.
What does phytoplankton produce in large quantities?
Answer : Oxygen
Through photosynthesis, phytoplankton produces much of Earth's oxygen.
Medium
How many hearts does an octopus have?
Answer : Three
An octopus has one systemic heart and two branchial hearts.
Which ocean current warms the climate of Western Europe?
Answer : The Gulf Stream
The Gulf Stream carries warm water across the North Atlantic.
Coral bleaching results from the expulsion of what?
Answer : Symbiotic algae
Stressed coral expels the algae that color and feed it.
What is the largest fish in the world?
Answer : The whale shark
The whale shark can exceed 12 meters.
Which marine mammal cracks shellfish with a stone?
Answer : The sea otter
The sea otter uses stones as tools.
What is the narwhal's tusk?
Answer : An elongated tooth
The narwhal's tusk is a spiral tooth growing through the lip.
Where do mangroves grow?
Answer : On tropical coasts, in salt water
Mangrove trees tolerate the salt water of tropical coasts.
In which ocean is the Sargasso Sea?
Answer : The North Atlantic
The Sargasso Sea is a region of the North Atlantic with no coastline.
Hard
What powers the ecosystems around deep hydrothermal vents?
Answer : Bacterial chemosynthesis
Bacteria there make organic matter from chemical compounds.
To which phylum do starfish and sea urchins belong?
Answer : Echinoderms
Starfish and sea urchins are echinoderms.
What is the sperm whale's main prey?
Answer : Squid
The sperm whale dives deep to hunt squid.
Which of these animals is NOT a pinniped?
Answer : The manatee
The manatee is a sirenian, not a pinniped.
What do a shark's ampullae of Lorenzini detect?
Answer : Electric fields
These organs sense the faint electric fields of prey.
Which deep-sea fish uses a glowing lure to hunt?
Answer : The anglerfish
The anglerfish attracts prey with a bioluminescent lure.
Roughly what share of Earth's surface do the oceans cover?
Answer : 71%
The oceans cover about 71% of the globe's surface.
What drives thermohaline circulation?
Answer : Differences in temperature and salinity
It depends on water density, set by temperature and salt.
Expert
Which living cephalopod has an external shell?
Answer : The nautilus
The nautilus lives in an external chambered shell.
What is the ocean zone deeper than 6,000 m called?
Answer : The hadal zone
The hadal zone corresponds to the deep ocean trenches.
What relationship links cleaner fish and the fish they clean?
Answer : Mutualism
The cleaner eats parasites and the client is rid of them.
In which ocean gyre is the Pacific "garbage patch" located?
Answer : The North Pacific subtropical gyre
Currents there concentrate floating debris.
What is "marine snow"?
Answer : Organic debris falling toward the seafloor
It is organic particles slowly sinking into the deep.
To which order do the manatee and dugong belong?
Answer : Sirenia
Manatees and dugongs are the living sirenians.
Which eel species migrates to the Sargasso Sea to spawn?
Answer : The European eel
The European eel spawns in the Sargasso Sea.
Which gas absorbed by the ocean causes its acidification?
Answer : Carbon dioxide
Dissolved CO2 forms carbonic acid in seawater.
Related themes
Play the Oceans & Marine Life quizzes