Getting your questions ready
Getting your questions ready
Beat the crowd
10 questions No timer
50 free Sea Life trivia questions with answers — trivia quiz, new questions added Aug 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 50 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 50 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; a female keeps travelling and hunting with her pod for decades after her last calf.
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 reinforced with goethite, an iron mineral, and tested at a tensile strength of up to 6.5 GPa, beating spider silk's 4.5 GPa.
Q 06Seahorses must eat almost constantly because their very simple gut lacks which organ?
A stomach
A stomach is missing from the seahorse's extremely simple gut, so food passes through fast and it must keep feeding to stay alive.
Q 07Which fish was filmed in 2023 at 8,336 m in the Izu–Ogasawara Trench, deeper than any fish had been seen before?
A snailfish
A snailfish took the record from earlier snailfish filmed at 8,145 m and 8,178 m in the Mariana Trench in 2014 and 2017; the deepest species have no swim bladder, so they do not burst when raised.
Q 08The green sea turtle takes its name from the colour of which part of its body, not its shell?
Its fat
Its fat is green from a diet of seagrass, lying in a layer between the organs and the shell, while the carapace 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 13How many eyes does a box jellyfish have, set in clusters on four sensory structures called rhopalia?
24
24 eyes in total sit at the ends of sensory structures called rhopalia, which are wired to the jellyfish's ring nerve.
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 sunfish, was found dead in 2021 off which Atlantic islands?
The Azores
The Azores fish was a Mola alexandrini, a species that reaches 3.3 m; it beat the previous record, a 2,300-kg sunfish caught off Kamogawa, Japan, in 1996, by nearly half a tonne.
Q 23Which sea turtle's flexible carapace is built to withstand the pressure of dives to 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 entire chewing apparatus carries the name because Aristotle described it in his History of Animals, in a passage later translated by D'Arcy Thompson.
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 transverse teeth that turn it into a saw, and sawfish are rays rather than sharks despite their shark-like build.
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 280-kg bluefin tuna for a record 333.6 million yen in January 2019?
Tokyo
Tokyo's new-year auction is a publicity contest, which is why the 280-kg Pacific bluefin went for about US$3.1 million on 5 January 2019, far above its market value.
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, head just below or at the surface or pointing straight down, a habit researchers have watched in whole pods.
Leatherback turtles have a carapace of unique design, and the flexible skin over it may let them grow and shrink insulating stores for deep dives and long migrations.
Q 24Human eyes carry four types of photoreceptor cell; a mantis shrimp's eyes have up to how many?
16
16 types at the top of the range (12 at least) let mantis shrimp see from deep ultraviolet to far-red and also detect polarised light.
Q 25The naval torpedo took its name from a genus of which fish, itself named from the Latin for 'numb'?
Electric rays
Electric rays of the genus Torpedo deliver a shock that leaves the victim numb, which is what torpidus means; the weapon simply borrowed the fish's 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 whale shark caught in 1996 carried roughly how many pups, proving whale sharks bear live young?
300
300 or so pups in one female showed that whale sharks are ovoviviparous: the eggs hatch inside the mother and the young are born live.
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, or a 'smuck', is the collective noun; jellyfish are built mostly of mesoglea, a jelly that is 95% or more water with collagen fibres.