Sea Life Trivia
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97 free Sea Life trivia questions with answers — trivia quiz, new questions added Oct 2026.
The ocean is where the rules of life get strange. It holds an animal that was alive when Columbus sailed, a fish that was filmed more than eight kilometres down, a worm that sits in water hot enough to scald, and a whale that sleeps standing on its head. These 97 questions work through the sea's big families: sharks and rays, whales, octopus and squid, jellyfish, the crowd on a reef, the deep-sea specialists, sea turtles, seahorses and their cousins, then the size, depth and age records that keep getting broken. Every stem carries a clue, so a good guesser can reason toward the answer. It is built for a pub round, a classroom or a phone on the sofa. Play it on screen with instant explanations, or print it and read the questions aloud. Every answer is cited to a reference page.
30 of 97 questions with answers and explanations. Play the quiz
Q 01Which marine mammal, like humans, is one of the few animals whose females live decades after they stop breeding?
Orca
Orcas are among the few animals that undergo menopause; older females lead the pod to salmon, most of all in years when the fish are scarce, which may be why they live on for decades.
Q 02'Ming', caught off Iceland in 2006 and aged at 507 years, was the oldest known individual of what kind of animal?
A clam
A clam of the ocean quahog species, Ming was named by Sunday Times journalists after the Chinese dynasty in power when it was born around 1499.
Q 03What decides whether a sea turtle hatchling is male or female, rather than its chromosomes?
Nest temperature
Nest temperature sets the sex: warmer sand produces female hatchlings and cooler sand males, a system called temperature-dependent sex determination.
Q 04Which deep-water fish from off Australia was voted the world's ugliest animal in a 2013 online poll?
Blobfish
The blobfish won the Ugly Animal Preservation Society's vote and became its mascot; at 600–1,200 m its gelatinous flesh holds its shape and looks far less droopy.
Q 05Which shore snail's teeth outperform spider silk as the strongest known biological material?
Limpet
Limpet teeth are packed with fine fibres of goethite, an iron mineral, which makes them stronger than spider silk, the record holder among natural materials until they were tested.
Q 06Seahorses must eat almost constantly because their very simple gut lacks which organ?
A stomach
A stomach is missing, so food rushes straight through: a seahorse spends its day anchored by its tail, sucking in tiny crustaceans as they drift within reach.
Q 07Which fish was filmed in 2022 at 8,336 m in the Izu–Ogasawara Trench, deeper than any fish had been seen before?
A snailfish
A snailfish of the genus Pseudoliparis, filmed by a baited camera lander, beat the 8,178 m record set in the Mariana Trench; the expedition's leader thinks no fish can survive much deeper.
Q 08The green sea turtle takes its name from the colour of which part of its body, not its shell?
Its fat
Its fat gives the green turtle its name, a colour long put down to its diet of seagrass and algae, although other sea turtles have greenish fat too; the shell itself is olive to black.
Q 09Inky the octopus made world news in 2016 by slipping out of Napier's National Aquarium through what?
A drain pipe
A drain pipe running out to sea was Inky's exit: the common New Zealand octopus left his tank, crawled across the floor and vanished down it.
Q 10Two-metre geometric circles in the sand off Japan's Ryukyu Islands turned out to be the nests of which fish?
A pufferfish
A pufferfish, Torquigener albomaculosus, sculpts the ridged 2 m circles: males build them to attract females, and the species was described from specimens off Amami Ōshima.
Q 11What do sea otters wrap around themselves before resting so they do not drift out to sea?
Kelp
Kelp fronds act as an anchor for a resting otter, and a foraging mother leaves her pup wrapped in kelp on the surface while she dives; it cries loudly until she returns.
Q 12Moray eels are the only animals known to seize prey with a second set of what, shot forward from the throat?
Jaws
Pharyngeal jaws sit far back in the head and look like the mouth's own jaws, complete with tiny teeth; the eel launches them to haul prey down its gullet.
Q 13Which jellyfish sees with 24 eyes, some complete with a lens, cornea and retina?
Box jellyfish
The box jellyfish carries six eyes on each of four sensory clubs called rhopalia, and uses its lens eyes to steer around obstacles in its path.
Q 21Which deep-sea crustacean, a relative of the garden woodlouse, can reach 50 cm long?
The giant isopod
The giant isopod Bathynomus giganteus usually runs 19–36 cm, and the largest confirmed specimen measured about 50 cm; a 76-cm claim came only from the popular press.
Q 22The heaviest bony fish ever recorded, a 2,744-kg giant found off the Azores, was what kind of fish?
A sunfish
A sunfish of the species Mola alexandrini, it was found floating dead off Faial island in December 2021 and had to be hauled back to port before anyone could weigh it.
Q 23Which sea turtle is the deepest diver, recorded going down about 1,200 m?
Leatherback
Q 14'Aristotle's lantern', named from his History of Animals, is the chewing organ of which creature?
The sea urchin
The sea urchin's chewing apparatus takes the name from a passage in Aristotle's History of Animals, though a 2008 study argued he was likening the animal's whole shell, not its mouthparts, to a lantern.
Q 15A sawfish's toothed 'saw' is an extension of which part of the ray's body?
Its snout
Its snout, or rostrum, is lined with teeth and packed with electroreceptors, so the saw both detects prey and slashes at it; despite their shark-like build, sawfish are rays.
Q 16Nesting sea turtles seem to weep on the beach; what are the tears actually getting rid of?
Excess salt
Excess salt leaves through a lachrymal gland in each eye socket, making the tears saltier than seawater; reptile kidneys cannot produce urine that concentrated.
Q 17When startled, some sea cucumbers defend themselves by expelling what through their rear end?
Their own guts
Their own guts: sea cucumbers can eviscerate, expelling the intestine and other organs through the rear end and regrowing them; some reef species instead fire sticky Cuvierian tubules out of the cloaca to tangle an attacker.
Q 18Which city's Toyosu fish market sold a single bluefin tuna for 333.6 million yen at its first auction of 2019?
Tokyo
Tokyo's first auction of the year draws showpiece bids: sushi-chain owner Kiyoshi Kimura paid about US$3.1 million for the fish on 5 January 2019, around double the previous record.
Q 19Migrating sea turtles cross open ocean and find their way home by sensing what?
Earth's magnetic field
Earth's magnetic field gives sea turtles both a map and a compass sense, called magnetoreception, which lets them hold course inside strong ocean gyres.
Q 20Which cetacean has been filmed dozing in groups, hanging motionless and upright with its head near the surface?
The sperm whale
The sperm whale rests in short bouts this way; a 2008 study that tagged the whales found the naps add up to only about 7% of their time.
Leatherback turtles, named for the rubbery skin they have in place of a bony shell, have been recorded diving more than 1,200 m, deeper than most marine mammals go.
Q 24Which crustacean's eyes carry at least 12 types of photoreceptor, against four in humans?
Mantis shrimp
The mantis shrimp sees from deep ultraviolet to far-red and detects polarised light, yet a 2014 study found it surprisingly poor at telling similar colours apart.
Q 25The naval torpedo took its name from a genus of which fish?
Electric rays
Electric rays of the genus Torpedo stun with a shock; the Latin torpedo already meant both 'numbness' and the fish itself, and the weapon simply borrowed the name.
Q 26The chalky 'cuttlebone' sold for caged birds to peck is which part of a cuttlefish?
Its internal shell
Its internal shell is a brittle, gas-filled buoyancy organ found in every member of the family Sepiidae, and pet shops sell it as a calcium supplement for birds, reptiles and snails.
Q 27A deep-sea octopus in Monterey Canyon guarded one clutch of eggs for how long, a record for any animal?
53 months
53 months is the longest egg-brooding known in any animal; the Graneledone boreopacifica mother was monitored by the Monterey Bay Aquarium Research Institute, and that vigil alone outlasts most octopuses' entire lives.
Q 28A 10.6-metre female found carrying about 300 embryos proved that which shark bears live young?
Whale shark
The whale shark's breeding was long debated: an egg found in the Gulf of Mexico in the 1950s suggested it laid them, until this female showed the eggs hatch inside the mother.
Q 29Millions of glowing firefly squid gather each spring to spawn in which Japanese bay, lighting its shores blue?
Toyama Bay
Toyama Bay fills with firefly squid on their yearly breeding migration; they flash blue light from photophores, and the glowing run draws tourists as well as fishing boats.
Q 30A group of jellyfish drifting together is known by which collective name?
A smack
A smack is the collective noun, and a big one can do damage: in 2011 a mass of jellyfish clogged the seawater filters at Scotland's Torness nuclear plant, and both reactors were shut down.