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50 free Hard Otter trivia questions with answers — nature quiz, new questions added Aug 2026.
This is the hard otter trivia quiz. If you already know that sea otters use rocks as tools, sleep in rafts and have the densest fur of any animal, these 50 questions go further: which otter has no functional scent glands, why sea otter teeth sometimes turn purple, the year the species was described by Linnaeus, the island where nuclear tests forced a mass relocation, and the Japanese prefecture whose official animal has been extinct since 2012. The set covers all 14 living species, from the giant otter of the Amazon to the marine otter of Chile and the near-vanished hairy-nosed otter of Southeast Asia, plus the maritime fur trade, the 1911 protection treaty, the Exxon Valdez, reintroductions from Vancouver Island to Kentucky, the urban otters of Singapore, and the otters of Tarka and Ring of Bright Water. It is written for people who have read the field guides. Every answer was checked against a primary or encyclopedic source before publishing and each question carries its citation. If you want a warm-up, start with our main otter trivia quiz and come back for this one.
30 of 50 questions with answers and explanations. Play the quiz
Q 01Potamotherium valetoni, the earliest known otter species, lived on which continent?
Europe
The African clawless otter, by contrast, does not appear in the fossil record until the Pleistocene.
Q 02Besides lacking a long muscular tail, the sea otter is unique among mustelids in lacking what?
Functional anal scent glands
It is also the only mustelid able to spend its whole life without leaving the water.
Q 03Roughly what share of its body weight must a Eurasian otter eat every day to stay warm?
15%
Sea otters need even more, 20 to 25 percent or higher. In water of 10 °C an otter must catch about 100 grams of fish an hour just to survive.
Q 04The first otter genus, Mionictis, evolved in the Early Miocene from which animals?
Badgers that adapted to semi-aquatic life
Otters remain part of the family Mustelidae alongside badgers, weasels, martens and minks.
Q 05Between 1958 and 1963 the 11 otter hunts of England and Wales killed how many otters between them?
1,065
Hunters notched their poles after each kill and prized the animal's baculum, or penis bone, as a tie-pin.
Q 06A 2011 IUCN review found otter attacks on humans from 1875 to 2010 were most common in which US state?
Florida
Most involved the North American river otter, and rabies featured in about a third of anecdotal reports. Eighty percent of bite victims never seek treatment.
Q 07As late as 1982, some scientists thought the sea otter was closer to which animals than to other mustelids?
Earless seals
Genetics settled it: the sea otter shares an ancestor about five million years ago with the Eurasian, African clawless and Asian small-clawed otters.
Q 08Under what scientific name did Linnaeus originally describe the sea otter in 1758?
Lutra marina
The name went through many changes before Enhydra lutris, Greek for 'in the water' plus Latin for otter, was accepted in 1922. It was once called the sea beaver.
Q 09Which naturalist, shipwrecked with Bering in 1741, first described the sea otter scientifically?
Georg Steller
The survivors spent the winter on Bering Island hunting the animals and gambling with the pelts, kicking off 170 years of commercial slaughter.
Q 10What nickname did sea otter pelts earn after Cook's crew sold them for high prices in China in the 1770s?
Soft gold
Cook had bought the furs from First Nations people on Vancouver Island in 1778. Word of the profits drew traders from across the Atlantic world.
Q 11By the end of the fur trade in 1911, the world sea otter population had fallen to roughly what?
1,000 to 2,000
Numbers had once been estimated at 150,000 to 300,000. The species now occupies about two-thirds of its former range but remains classed as endangered.
Q 12California's sea otters descend from about 50 animals found in 1938 near which landmark?
Bixby Creek Bridge
The historic California population had been about 16,000. That 1938 genetic bottleneck left lasting inbreeding and harmful mutations in the population.
Q 13Sea otters were moved off Amchitka Island in the late 1960s because the US government planned to use it for what?
Nuclear weapons tests
Q 21Why can a newborn sea otter pup float like a cork but not dive?
Its baby fur traps so much air after grooming
Mothers lick and fluff a newborn for hours. Twins occur in about 2 percent of births, but usually only one pup survives.
Q 22Which institution first raised sea otters from conception to adulthood, with the birth of Tichuk in 1979?
Seattle Aquarium
The same aquarium housed the oldest recorded female, Etika, who lived to 28, and the oldest male, Adaa. Sea otters are kept in more than 40 zoos and aquariums.
Q 23The famous 2007 YouTube video of two sea otters holding paws was filmed where?
The Atomic Energy Commission agreed to relocate hundreds of animals before a 1968 test. Some 700 sea otters were transplanted along the coast in the 1960s and 70s.
Q 14How many sea otters were moved from Alaska to Vancouver Island between 1969 and 1972?
89
The island's own remnant population had died out by 1929 despite the 1911 treaty. The transplants grew to more than 5,600 animals by 2013.
Q 15What did most of the 140 sea otters moved to San Nicolas Island in the late 1980s do?
Swam back to the mainland
Another twenty swam 119 km to San Miguel Island and had to be recaptured. The plan for an oil-spill insurance colony left just 30 otters there by 2005.
Q 16At least how many sea otters were killed by the 1989 Exxon Valdez spill in Prince William Sound?
2,800
Oiled fur loses its trapped air layer and the animals die of hypothermia. Lingering oil was still affecting the population in 2006.
Q 17Where does a sea otter stash food and its favourite rock while diving?
In loose pouches of skin under each foreleg
It prefers the left pouch. At the surface it floats on its back and uses its lower incisors to dig meat out of shellfish.
Q 18Why are a sea otter's teeth and bones sometimes stained purple?
From eating sea urchins
Its 32 teeth are flattened for crushing, and seals and sea otters are the only carnivores with two pairs of lower incisors instead of three.
Q 19An abalone grips its rock with a force equal to how many times its own body weight?
4,000
Otters have been timed at 45 blows in 15 seconds with a large stone. Sea otters are the only marine mammals that catch fish with their forepaws rather than their teeth.
Q 20How does a sea otter's metabolic rate compare with that of a similarly sized land mammal?
Two or three times higher
It eats 25 to 38 percent of its body weight daily and digests food in as little as three hours. Unusually for a marine mammal it also drinks seawater.
Vancouver Aquarium
It drew 1.5 million viewers in two weeks and was YouTube's most popular animal video at the time. Rescued pups Joey and Tofino from the same city later went viral too.
Q 24The nominate sea otter subspecies ranges across the Commander archipelago and which other island chain?
The Kuril Islands
It is the largest of the three subspecies, with a wider skull. E. l. kenyoni ranges from the Aleutians to Oregon and E. l. nereis lives off California.
Q 25Streamer DougDoug's birthday streams for which Monterey Bay Aquarium sea otter have raised over $1 million?
Rosa
The charity streams began in 2019. Rosa was one of the aquarium's surrogate mothers, raising stranded pups for release into the wild.
Q 26In Brazil the giant otter is called ariranha or onça-d'água, meaning what?
Water jaguar
Spanish speakers use lobo de río, river wolf, and perro de agua, water dog. All four names are still used across South America.
Q 27How can individual giant otters be identified from birth?
Unique cream markings on the throat
Researcher Nicole Duplaix's 1970s fieldwork was the first serious science on the species. Its fur is the shortest of any otter yet dense enough that water never reaches the skin.
Q 28Unusually for a mustelid, the giant otter is what?
Social and strictly diurnal
Family groups of three to eight are built around a dominant breeding pair and clear large 'campsites' near feeding areas. Poaching peaked in the 1950s and 60s.
Q 29In which year was the giant otter listed as endangered, with wild estimates under 5,000?
1999
The Guianas are among its last strongholds. Its wing-like tail and webbed feet make it a fast swimmer in the Amazon and Pantanal.
Q 30Which pollutants were mainly blamed for the Eurasian otter's collapse in the late 20th century?
PCBs and organochlorine pesticides
Recovery has been striking: UK sites with otters rose 55 percent between 1994 and 2002.