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The sea otter's scientific name, *Enhydra lutris*, translates to 'water otter' in Latin.
Answer: False
Explanation: The scientific name *Enhydra lutris* combines the Greek *Enhydra* ('in water') and the Latin *lutris* ('otter'), reflecting its highly aquatic nature.
Sea otters are the heaviest members of the weasel family but among the smallest marine mammals.
Answer: True
Explanation: As the heaviest members of the Mustelidae family, sea otters typically weigh 14-45 kg, yet they rank among the smallest marine mammals.
What is the scientific name of the sea otter, and what do the parts of the name signify?
Answer: *Enhydra lutris*; 'in water' (Greek) and 'otter' (Latin)
Explanation: The scientific name *Enhydra lutris* combines the Greek *Enhydra* ('in water') and the Latin *lutris* ('otter'), reflecting its highly aquatic nature.
How does a sea otter's weight compare to other members of its family (Mustelidae)?
Answer: They are the heaviest members.
Explanation: As the heaviest members of the Mustelidae family, sea otters typically weigh 14-45 kg, yet they rank among the smallest marine mammals.
Unlike most marine mammals, sea otters rely on a thick layer of blubber for insulation.
Answer: False
Explanation: Unlike pinnipeds, which rely on blubber, sea otters utilize exceptionally dense fur for thermal insulation.
Sea otters possess adaptations like closable nostrils and ears, allowing them to live entirely in the ocean.
Answer: True
Explanation: Sea otters are fully adapted to marine life, featuring closable nostrils and ears, alongside insulating fur, enabling perpetual ocean habitation.
Sea otters returned to a marine existence much earlier than whales and dolphins.
Answer: False
Explanation: Sea otters are recent marine mammals, returning to the ocean approximately three million years ago, significantly later than cetaceans and pinnipeds.
Sea otters maintain body heat primarily through a layer of insulating blubber.
Answer: False
Explanation: Sea otters rely on dense fur for insulation, unlike pinnipeds which primarily use blubber.
The sea otter's flexible skeleton aids in grooming its dense fur.
Answer: True
Explanation: A sea otter's flexible skeleton and loose skin facilitate effective grooming of its dense fur, crucial for insulation.
Sea otters use their hind feet and tail for underwater propulsion.
Answer: True
Explanation: Underwater propulsion for sea otters is primarily achieved through the coordinated movement of their hindquarters, tail, and webbed hind feet.
Sea otters have a lower metabolic rate than terrestrial mammals of similar size.
Answer: False
Explanation: Sea otters possess a metabolic rate two to three times higher than terrestrial mammals of comparable size, essential for thermoregulation.
A sea otter's large lung capacity primarily aids in diving endurance.
Answer: False
Explanation: A sea otter's significantly larger lung capacity primarily contributes to its buoyancy, facilitating surface flotation.
Pinnipeds, like seals, use dense fur for insulation, similar to sea otters.
Answer: False
Explanation: Pinnipeds, unlike sea otters, primarily use blubber for insulation, rather than dense fur.
The gradual shedding of sea otter fur ensures constant insulation without seasonal molting.
Answer: True
Explanation: Sea otters maintain consistent insulation year-round due to a gradual fur shedding process, avoiding seasonal molting.
The sea otter's high buoyancy is mainly due to its thick blubber layer.
Answer: False
Explanation: Sea otter buoyancy is primarily attributed to their large lung capacity and trapped fur air, not a blubber layer.
What is the sea otter's primary method of insulation against cold water?
Answer: Extremely dense fur that traps air.
Explanation: The sea otter's primary insulation is its exceptionally dense fur, which traps air and eliminates the need for a blubber layer common in other marine mammals.
Which adaptation allows sea otters to remain indefinitely in the ocean?
Answer: Closable nostrils and ears, plus insulating fur.
Explanation: Adaptations such as closable nostrils and ears, coupled with insulating fur, enable sea otters to live perpetually in the ocean.
Compared to other marine mammals like whales and seals, sea otters are:
Answer: Relatively recent arrivals, returning to the ocean about 3 million years ago.
Explanation: Sea otters are recent marine mammals, returning to the ocean approximately three million years ago, significantly later than cetaceans and pinnipeds.
What is the density of sea otter fur?
Answer: Up to 150,000 hairs per square centimeter.
Explanation: Sea otter fur is the densest of any animal, reaching up to 150,000 hairs per square centimeter, providing primary insulation.
What is the function of the sea otter's loose skin and flexible skeleton?
Answer: To facilitate effective grooming of their dense fur.
Explanation: A sea otter's flexible skeleton and loose skin facilitate effective grooming of its dense fur, crucial for insulation.
How does the sea otter's metabolism compare to that of similar-sized terrestrial mammals?
Answer: It is two to three times higher.
Explanation: Sea otters possess a metabolic rate two to three times higher than terrestrial mammals of comparable size, essential for thermoregulation.
What is the primary difference in insulation between sea otters and pinnipeds?
Answer: Sea otters use fur; pinnipeds use blubber.
Explanation: Sea otters rely on dense fur for insulation, unlike pinnipeds which primarily use blubber.
What potential disadvantage can arise from the air trapped in a sea otter's fur during deep dives?
Answer: Increased water pressure may compress the fur, reducing insulation.
Explanation: During deep dives, increased water pressure can compress the air trapped in sea otter fur, potentially reducing insulation effectiveness.
The primary diet of sea otters consists mainly of large fish and squid.
Answer: False
Explanation: The sea otter's diet predominantly comprises marine invertebrates like sea urchins, mollusks, and crustaceans, with fish forming a secondary component.
Sea otters are known to use rocks as tools to break open shellfish.
Answer: True
Explanation: Sea otters exhibit tool use, employing rocks to dislodge prey and crack open the shells of hard-bodied invertebrates.
Sea otters use a loose skin pouch under their foreleg to store rocks for tool use.
Answer: True
Explanation: A sea otter's loose skin pouch under its foreleg is utilized for storing foraged food and sometimes rocks used as tools.
Sea otters typically hold their breath for over ten minutes while foraging.
Answer: False
Explanation: Sea otters typically dive for foraging for approximately one minute, rarely exceeding four minutes, although they can hold their breath for up to five minutes.
Sea otters consume sea urchins by crushing the entire shell before eating.
Answer: False
Explanation: Sea otters consume sea urchins by biting through the softer underside spines and extracting the contents.
Fish constitute the majority of the sea otter's diet along the North American coast south of Alaska.
Answer: False
Explanation: South of Alaska, sea otters' diets are primarily benthic invertebrates, with fish being a minor component.
Sea otters sleep floating individually, never grouping together.
Answer: False
Explanation: Sea otters frequently rest in groups known as 'rafts,' often holding paws or using kelp to maintain cohesion.
The purple staining on sea otter teeth and bones is caused by microcystin poisoning.
Answer: False
Explanation: Purple staining on sea otter teeth and bones results from consuming sea urchins, whose pigments are absorbed into tissues.
Sea otters catch fish using their teeth, much like seals do.
Answer: False
Explanation: Sea otters capture fish with their forepaws, contrasting with seals that typically use their teeth.
What type of food forms the bulk of the sea otter's diet?
Answer: Marine invertebrates like sea urchins and mollusks.
Explanation: The sea otter's diet predominantly comprises marine invertebrates like sea urchins, mollusks, and crustaceans, with fish forming a secondary component.
Sea otters are notable for using which items as tools?
Answer: Rocks to crack open shellfish.
Explanation: Sea otters exhibit tool use, employing rocks to dislodge prey and crack open the shells of hard-bodied invertebrates.
What is the purpose of the loose skin pouch under a sea otter's foreleg?
Answer: To store food collected during foraging.
Explanation: A sea otter's loose skin pouch under its foreleg is utilized for storing foraged food and sometimes rocks used as tools.
What is the typical duration of a sea otter's foraging dive?
Answer: Around 1 minute, rarely exceeding 4 minutes.
Explanation: Sea otters typically dive for foraging for approximately one minute, rarely exceeding four minutes, although they can hold their breath for up to five minutes.
How do sea otters typically eat sea urchins?
Answer: Biting the underside and licking out the contents.
Explanation: Sea otters consume sea urchins by biting through the softer underside spines and extracting the contents.
In northern regions, what percentage of a sea otter's diet can sometimes be fish?
Answer: Up to 50%
Explanation: In some northern areas, fish can constitute up to 50% of a sea otter's diet.
How do sea otters prevent drifting apart while resting in groups ('rafts')?
Answer: They hold paws or wrap themselves in kelp.
Explanation: Sea otters frequently rest in groups known as 'rafts,' often holding paws or using kelp to maintain cohesion.
What is the significance of the purple staining sometimes seen on sea otter teeth and bones?
Answer: It is a result of consuming sea urchins.
Explanation: Purple staining on sea otter teeth and bones results from consuming sea urchins, whose pigments are absorbed into tissues.
Which of the following is NOT a typical prey item for sea otters?
Answer: Kelp
Explanation: The sea otter's diet predominantly comprises marine invertebrates like sea urchins, mollusks, and crustaceans, with fish forming a secondary component; kelp is not a prey item.
How do sea otters typically catch fish?
Answer: Employing their forepaws to capture them.
Explanation: Sea otters capture fish with their forepaws, contrasting with seals that typically use their teeth.
Sea otters are considered a keystone species because they exclusively prey on fish, influencing the marine food web.
Answer: False
Explanation: The sea otter functions as a keystone species by regulating herbivore populations, such as sea urchins, thereby preserving kelp forest ecosystems.
By consuming sea urchins, sea otters help protect kelp forests from destruction.
Answer: True
Explanation: Sea otters protect kelp forests by controlling sea urchin populations, preventing overgrazing.
Sea otters contribute to carbon sequestration by maintaining kelp forests.
Answer: True
Explanation: Sea otters indirectly contribute to carbon sequestration by preserving kelp forests, which absorb atmospheric carbon dioxide.
Sea otters help manage red king crab populations in the Bering Sea by preying on them.
Answer: True
Explanation: Sea otters contribute to managing Bering Sea red king crab populations through predation.
Sea otters are important for maintaining kelp forests by controlling populations of abalone.
Answer: False
Explanation: Sea otters maintain kelp forests primarily by controlling sea urchin populations, not abalone.
Why is the sea otter considered a keystone species?
Answer: It prevents sea urchins from destroying kelp forests.
Explanation: The sea otter functions as a keystone species by regulating herbivore populations, such as sea urchins, thereby preserving kelp forest ecosystems.
How do sea otters contribute to the health of kelp forests?
Answer: By preying on sea urchins that eat kelp.
Explanation: Sea otters protect kelp forests by controlling sea urchin populations, preventing overgrazing.
Sea otters exhibit delayed implantation, allowing flexibility in their gestation period.
Answer: True
Explanation: Sea otters exhibit delayed implantation, allowing for a variable gestation period of four to twelve months.
Sea otter pups nurse for a shorter period in Alaska than in California.
Answer: False
Explanation: Sea otter pups nurse for six to eight months in California and four to twelve months in Alaska.
Sea otters have a shorter average lifespan than most terrestrial mammals.
Answer: True
Explanation: Wild sea otters typically have an average lifespan of 10 to 20 years, which is shorter than many terrestrial mammals.
Male sea otters defend territories primarily during the summer months.
Answer: False
Explanation: Male sea otters typically defend territories during the spring and autumn breeding seasons.
Sea otters typically give birth to twins, with both pups usually surviving.
Answer: False
Explanation: Sea otters typically give birth to a single pup; twins are rare and seldom survive.
What reproductive adaptation allows sea otters to have a variable gestation period (4-12 months)?
Answer: Delayed implantation of the fertilized egg.
Explanation: Sea otters exhibit delayed implantation, allowing for a variable gestation period of four to twelve months.
Sea otters primarily inhabit the Atlantic Ocean's coastal regions.
Answer: False
Explanation: Sea otters are indigenous to the coastal zones of the North Pacific Ocean.
The Southern sea otter subspecies (*E. l. nereis*) is found along the coast of California.
Answer: True
Explanation: The Southern sea otter subspecies (*E. l. nereis*) inhabits the California coast.
The Asian sea otter subspecies is characterized by shorter nasal bones compared to other subspecies.
Answer: True
Explanation: The Asian sea otter subspecies (*E. l. lutris*) is distinguished by a wider skull and shorter nasal bones compared to other subspecies.
Which ocean basin is the primary habitat for wild sea otters?
Answer: North Pacific Ocean
Explanation: Sea otters are indigenous to the coastal zones of the North Pacific Ocean.
Which subspecies of sea otter is found from Alaska down to Oregon?
Answer: *Enhydra lutris kenyoni*
Explanation: The Northern sea otter subspecies (*E. l. kenyoni*) ranges from Alaska to Oregon.
What is a key physical difference noted for the Asian sea otter subspecies (*E. l. lutris*)?
Answer: A wider skull.
Explanation: The Asian sea otter subspecies (*E. l. lutris*) is distinguished by a wider skull and shorter nasal bones compared to other subspecies.
The fur trade in the 18th century significantly increased sea otter populations.
Answer: False
Explanation: The 18th-century fur trade drastically reduced sea otter populations due to extensive hunting for their pelts.
The recovery of sea otter populations is primarily attributed to natural environmental changes.
Answer: False
Explanation: Sea otter population recovery is primarily attributed to conservation measures, including hunting bans and reintroduction programs.
Sea otters are no longer classified as endangered due to successful conservation efforts.
Answer: False
Explanation: Despite conservation successes, sea otters remain classified as endangered due to ongoing threats like pollution, predation, and habitat conflicts.
Great white sharks are the primary predators of sea otters across all their habitats.
Answer: False
Explanation: While great white sharks prey on sea otters in California, orcas are considered the primary predators across their habitats.
The parasite *Toxoplasma gondii* poses no significant threat to sea otter populations.
Answer: False
Explanation: The parasite *Toxoplasma gondii*, transmitted via runoff, poses a significant and potentially fatal threat to sea otters.
Sea otters have a negative economic impact by exclusively consuming commercially valuable shellfish.
Answer: False
Explanation: While sea otters consume commercially valuable shellfish, their ecological role in maintaining kelp forests also supports fisheries and tourism, creating a complex economic impact.
The 'otter-free zone' experiment in California was successful in managing human-otter conflicts.
Answer: False
Explanation: The 'otter-free zone' experiment in California faced challenges and was ultimately considered unsuccessful in managing human-otter conflicts.
Microcystin, a toxin from cyanobacteria, can poison sea otters if they consume contaminated shellfish.
Answer: True
Explanation: Microcystin, a cyanobacterial toxin found in shellfish, can poison and prove fatal to sea otters.
The 2016 California sea otter census indicated a population decline, jeopardizing recovery efforts.
Answer: False
Explanation: The 2016 California sea otter census indicated a population increase, meeting recovery thresholds.
Shark attacks are a minor cause of mortality for sea otters compared to diseases.
Answer: False
Explanation: Diseases, such as those caused by *Toxoplasma gondii*, are major causes of sea otter mortality, often exceeding that from shark attacks.
The decline in the Aleutian Islands sea otter population is primarily linked to habitat loss.
Answer: False
Explanation: The drastic decline in Aleutian Islands sea otter populations is primarily hypothesized to be due to increased predation by orcas.
Oil pollution harms sea otters mainly by poisoning them through ingestion.
Answer: False
Explanation: Oil pollution primarily harms sea otters by damaging their fur's insulation, leading to hypothermia, rather than direct poisoning.
Sea otters are culturally significant to indigenous North Pacific cultures, often featured in folklore and used for pelts.
Answer: True
Explanation: Sea otters hold significant cultural importance for indigenous North Pacific peoples, appearing in folklore and historically utilized for pelts and other materials.
What historical activity caused a severe decline in sea otter populations starting in the 18th century?
Answer: Extensive hunting for their valuable fur.
Explanation: The 18th-century fur trade drastically reduced sea otter populations due to extensive hunting for their pelts.
Which factor is NOT listed as a reason for sea otters remaining classified as endangered?
Answer: Competition with seals
Explanation: Despite conservation successes, sea otters remain classified as endangered due to ongoing threats like pollution, predation, and habitat conflicts.
Which of the following is identified as a primary predator of adult sea otters?
Answer: Orcas (Killer Whales)
Explanation: The primary predators of adult sea otters are orcas (killer whales).
What is the suspected primary cause of the drastic sea otter population decline in the Aleutian Islands?
Answer: Increased predation by orcas.
Explanation: The drastic decline in Aleutian Islands sea otter populations is primarily hypothesized to be due to increased predation by orcas.
What toxin, often associated with cat feces, can be fatal to sea otters?
Answer: *Toxoplasma gondii*
Explanation: The parasite *Toxoplasma gondii*, transmitted via runoff, poses a significant and potentially fatal threat to sea otters.
What is the main danger posed by oil spills to sea otters?
Answer: Loss of fur insulation leading to hypothermia.
Explanation: Oil pollution primarily harms sea otters by damaging their fur's insulation, leading to hypothermia, rather than direct poisoning.