Easy
Oceans & Marine Life
Tides, Depths & Reefs
The physics of the sea and the life that adapted to it.
Sample question
Start quiz
What is the deepest known point in the ocean?
Marine Mammals and Their Ways
Several separate groups of land mammals went back to the water, and each solved the same problems in a slightly different way.
About this topic
Mammals returned to the sea at least four times, and the groups involved are not close relatives. Whales and dolphins descend from hoofed land animals; seals and sea lions from carnivores related to bears and otters; manatees and dugongs from the same ancestry as elephants; sea otters from the weasel family. Each lineage had to solve the same list of problems from scratch — staying warm, holding a breath, drinking without fresh water, and giving birth to an air-breathing young. The solutions differ in revealing ways. Most groups insulate with blubber; the sea otter does it with fur so dense it traps a layer of air. Whales hunt by sound because sound carries well and light does not. Diving physiology in seals and whales runs almost the opposite way to a human diver's, with the lungs deliberately emptied rather than filled. The questions here cover feeding, senses, diving and migration.
Questions & answers
Marine Mammals and Their Ways: all 10 questions and answers
Every question in this quiz is listed below with its correct answer and the reasoning behind it. Play first if you would rather not see the answers — or read through as a study sheet.
Play it insteadShow all answers and explanationsHide answers
-
1Baleen whales feed by doing what?
- A Grazing seaweed and algae from shallow rocks
- B Straining small prey from mouthfuls of water through plates of keratin Correct
- C Crushing shellfish between flattened molar teeth
- D Spearing individual fish with a single elongated tooth
Answer: B. Straining small prey from mouthfuls of water through plates of keratin
Why: The plates hang from the upper jaw and fray into a bristly mat along the inner edge. Toothed whales, the other main group, take prey one animal at a time.
-
2Which whale carries a long spiral tusk that is really an overgrown tooth?
- A The narwhal Correct
- B The beluga
- C The minke
- D The pilot whale
Answer: A. The narwhal
Why: It is usually the left canine of a male, grown out through the lip, and it is packed with nerve endings that may sense the water around it.
-
3Echolocation in toothed whales works by what means?
- A Sensing electrical fields given off by prey
- B Detecting small changes in water temperature
- C Following chemical trails left in the water
- D Emitting rapid clicks and interpreting the echoes that return Correct
Answer: D. Emitting rapid clicks and interpreting the echoes that return
Why: The clicks are focused by a fatty structure in the forehead called the melon, and the returning sound is picked up through the lower jaw rather than the ears.
-
4Which group of marine mammals includes the manatee and the dugong?
- A Cetaceans
- B Mustelids
- C Sirenians Correct
- D Pinnipeds
Answer: C. Sirenians
Why: They are plant-eaters that graze on seagrass, and they are more closely related to elephants than to seals. The group name comes from the sirens of Greek myth.
-
5What distinguishes a true seal from a sea lion?
- A True seals give birth at sea rather than on land
- B True seals have no external ear flaps and cannot rotate their hind limbs forward Correct
- C True seals are always considerably larger
- D Sea lions live only in fresh water
Answer: B. True seals have no external ear flaps and cannot rotate their hind limbs forward
Why: That limb difference is why a sea lion can walk on all fours on land while a true seal has to hump along on its belly.
-
6Sea otters stay warm in cold water without a thick layer of blubber by relying on what?
- A An exceptionally dense fur coat that traps a layer of air Correct
- B A very high-fat diet and nothing else
- C Long periods basking on sun-warmed rocks
- D Slowing the heartbeat almost to a stop
Answer: A. An exceptionally dense fur coat that traps a layer of air
Why: Their fur is the densest of any mammal, and they groom constantly because matted or oiled fur loses the trapped air and the insulation with it.
-
7Why do diving seals and whales avoid the decompression sickness that can affect human divers?
- A They breathe a different mixture of gases at the surface
- B Their blood is chemically unable to dissolve nitrogen
- C They ascend far more slowly than any human diver
- D They exhale before diving and let the lungs collapse, so little nitrogen dissolves into the blood Correct
Answer: D. They exhale before diving and let the lungs collapse, so little nitrogen dissolves into the blood
Why: Their oxygen store is carried in the blood and muscle instead of the lungs, helped by very high concentrations of the pigment myoglobin.
-
8Spermaceti, the waxy substance in a sperm whale's head, was historically valued for what?
- A Fixing dyes in woollen cloth
- B Preserving meat on long voyages
- C Making smokeless candles and fine lubricating oils Correct
- D Tanning and softening leather
Answer: C. Making smokeless candles and fine lubricating oils
Why: Demand for it drove much of the nineteenth-century whaling industry, and it was later used to lubricate precision machinery and instruments.
-
9Grey whales and humpbacks make long seasonal migrations chiefly in order to do what?
- A Reach river mouths where they can drink fresh water
- B Breed and calve in warm water while feeding in cold water Correct
- C Ride ocean currents that carry them along passively
- D Escape parasites that occur only at high latitudes
Answer: B. Breed and calve in warm water while feeding in cold water
Why: Cold seas hold far more food but are punishing for a newborn with little blubber, so calving grounds sit thousands of kilometres from feeding grounds.
-
10Polar bears are usually classed as marine mammals because of what?
- A They depend on sea ice for hunting and spend much of their lives out on it Correct
- B They give birth and nurse their young underwater
- C They have webbed hind flippers rather than feet
- D They are unable to survive for long on land
Answer: A. They depend on sea ice for hunting and spend much of their lives out on it
Why: Their main prey is seals taken at breathing holes and ice edges, and they swim well enough to cross stretches of open water between floes.
Frequently asked questions about Marine Mammals and Their Ways
How many questions are in Marine Mammals and Their Ways?
Marine Mammals and Their Ways has 10 questions and takes about 6 minutes to finish. It is rated Medium and sits in our Oceans & Marine Life category.
How is Marine Mammals and Their Ways scored?
Each of the 10 correct answers adds 10 XP, up to 100 XP for a clean run. Wrong answers cost you nothing, and your full question-by-question review is shown at the end.
Are the answers to Marine Mammals and Their Ways explained?
Yes. All 10 questions carry a written explanation of why the correct answer is right, so the quiz works as a study sheet as well as a test.
Can I replay Marine Mammals and Their Ways?
Yes, as often as you like. The questions and the answer options are reshuffled on each run, and you can use Practice Mistakes afterwards to retry only the ones you missed. No account is needed to play.
QuizKite Quality Guarantee
Every quiz on QuizKite is researched, written and fact-checked by hand against reliable references, with an explanation for each answer. Read our full Editorial Policy to learn more about our content standards.
Keep going
More Oceans & Marine Life
Hard
Oceans & Marine Life
Life in the Deep Sea
Bioluminescence, vent communities and the slow economy of a world without sunlight.
Sample question
Start quiz
Which name is given to the ocean layer below roughly 1,000 metres, where sunlight never…
Easy
Oceans & Marine Life
Whales, Dolphins and Porpoises
Ten questions on the mammals that went back to the water and how they eat, dive, sing and sleep.
Sample question
Start quiz
How does a baleen whale feed?
Medium
Oceans & Marine Life
Coral Reefs and the Shallow Sea
How a reef is built, what keeps it alive, and the animals that quietly run the place.
Sample question
Start quiz
The single-celled algae that live inside coral tissue are known as what?
Hard
Oceans & Marine Life
Currents, Trenches and the Sea Floor
Ten questions on how seawater moves around the planet and what the ground beneath it actually looks like.
Sample question
Start quiz
Spring tides, the largest tides of the month, happen when what occurs?
Medium
Oceans & Marine Life
Sharks, Rays and the Fish Between Them
Cartilage instead of bone, electrical senses, and the fish that break every rule.
Sample question
Start quiz
Sharks and rays differ from most fish because their skeletons are made of what?