Sea Cucumbers
0Loading crowd target
0Loading crowd target
6correct to beat the crowd
40 free Sea Cucumbers trivia questions with answers — trivia quiz, new questions added Oct 2026.
Sea cucumbers look like the least eventful animals on the seabed, which is exactly why the facts about them land so well. Their anatomy breaks most of the rules a person would expect an animal to follow, and their ways of dealing with a hungry crab are among the oddest in the ocean. This quiz covers the body and senses, the famous defences, the lodgers that move in uninvited, the swimmers and walkers of the deep sea, and the centuries-old trade that carries dried sea cucumber across Asia. Every answer comes with a short explanation, so each question doubles as a fun fact. It suits curious beginners, aquarium keepers, divers, students and anyone building a marine biology round for a quiz night.
30 of 40 questions with answers and explanations. Play the quiz
Q 01Sea cucumbers pump seawater in and out through the anus to carry out which vital function?
Breathing
Breathing is done by two branching respiratory trees just inside the anus, which draw oxygen from each gulp of seawater before it is squirted back out.
Q 02Which organ does every sea cucumber live its whole life without?
A brain
A brain is absent: the nerves form a ring around the mouth, and a sea cucumber can still move about after that ring has been surgically removed.
Q 03Some sea cucumbers scare off a crab by ejecting which parts of themselves, which later grow back?
Internal organs
Internal organs such as the gut are thrown out through the anus or a rupture near the mouth, a defence called evisceration. The animal lives off its reserves until replacements grow.
Q 04Which farm animal names Scotoplanes, the sea cucumbers that walk the deep seabed on stilt-like legs?
Pigs
Pigs give Scotoplanes the common name sea pigs, and the animals roam the abyssal plain in groups that early collectors counted in the hundreds.
Q 05Which slender, see-through fish is known for living inside the anus of a sea cucumber?
Pearlfish
Pearlfish shelter in the cloaca of a sea cucumber, and a few parasitic species go further and eat the host's gonads from the inside.
Q 06Some reef sea cucumbers defend themselves by firing what from the anus at an attacking crab or fish?
Sticky threads
Sticky threads called Cuvierian tubules swell to as much as 20 times their length in seawater and glue an attacker fast in under ten seconds while the sea cucumber crawls away.
Q 07A sea cucumber can pour itself through a narrow crack by loosening which protein in its body wall?
Collagen
Collagen fibres in the body wall can be unhooked until the animal all but liquefies, then locked together again so it sits firm inside its hiding place.
Q 08Enypniastes eximia, a swimming sea cucumber filmed off East Antarctica, goes by which unflattering nickname?
Headless chicken monster
Headless chicken monster is the popular name for this deep-sea swimmer, which uses webbed fins to rise as much as 1,000 metres above the seabed between meals.
Q 09Actinopyga sea cucumbers keep lodgers out of the anus with a ring of which hard structures?
Teeth
Teeth ring the anus of Actinopyga species, blocking the small fish, crabs and worms that set up home inside the bodies of other sea cucumbers.
Q 10Sea cucumbers belong to which animal phylum, along with starfish, brittle stars and sand dollars?
Echinoderms
Echinoderms share a five-part body plan, and in a sea cucumber it survives as five bands that run the length of the body from mouth to anus.
Q 11Campaigns against which soup ingredient made sea cucumber a popular replacement on Chinese menus?
Shark fin
Shark fin lost favour after campaigns against the soup, and sea cucumber, long served in Chinese soups and stews, stepped into its place.
Q 12Sea cucumbers drove the first recorded trade between Asia and the Indigenous peoples of which continent?
Australia
Australia's Arnhem Land coast drew fishing fleets from Makassar, in what is now Indonesia, which gathered sea cucumbers there to supply the markets of southern China.
Q 13Sea cucumbers, called namako in Japan, have inspired thousands of poems in which verse form?
Haiku
Haiku about namako run into the thousands, and a single English-language book translates almost 1,000 of them.
Q 21Dried sea cucumber is traded under which French name, a reshaping of the Portuguese bicho do mar?
Bêche-de-mer
Bêche-de-mer comes from the Portuguese bicho do mar, and the Pacific Community's long-running scientific bulletin on sea cucumbers takes the name for its title.
Q 22Which Indonesian word for sea cucumber gave English its name for gathering the animals by hand from small boats?
Trepang
Trepang gave English the verb trepanging, and the dried catch has to be boiled and soaked for days before it is soft enough to cook.
Q 23Which animals, the only other living class in their subphylum, are sea cucumbers' closest relatives?
Sea urchins
Q 14Which Greek philosopher's 'holothurion' gave sea cucumbers their scientific class name, Holothuroidea?
Aristotle
Aristotle listed the holothurion among sea creatures that seemed to lack sensation, alongside sponges, though nobody can be sure the animal he meant was a sea cucumber.
Q 15Holothurin, the toxin a stressed sea cucumber releases, behaves much like which household product?
Soap
Soap is the closest match: holothurin is a saponin, a surfactant that ruptures red blood cells and can kill other animals nearby.
Q 16Scientists first mistook Pelagothuria natatrix, the only sea cucumber that never visits the seabed, for which animal?
A jellyfish
A jellyfish is what a 2011 NOAA expedition thought it had photographed. The animal drifts beneath an umbrella-like veil and was only identified three years later.
Q 17Which fruit names the sea cucumber that crowds rock walls in New Zealand's Fiordland by the thousand?
Strawberry
Strawberry sea cucumbers pack together at up to 1,000 animals per square metre, which is why one stretch of Fiordland is known as the strawberry fields.
Q 18One sea cucumber can swallow more than 45 kilograms a year of which material, cleaning the seabed as it feeds?
Sediment
Sediment goes in at one end and comes out finer and purer at the other, once the animal has digested the organic scraps mixed into it.
Q 19Many sea cucumbers have flattened, disc-shaped cells in their body fluid that carry which oxygen-binding pigment?
Hemoglobin
Hemoglobin in those cells turns both the blood and the body-cavity fluid red in many species, a pigment only a handful of their brittle star relatives share.
Q 20Which country set up the world's first conservation reserve for sea cucumbers, in its Lakshadweep islands?
India
India protects sea cucumbers under the same wildlife schedule as tigers and lions, and the Lakshadweep reserve was created to curb smuggling to black markets abroad.
Sea urchins and sea cucumbers both lack arms and share a body plan based on a globe, stretched into a tube in one and armoured with spines in the other.
Q 24When the water grows too warm, some temperate sea cucumbers stop feeding and enter which state of dormancy?
Aestivation
Aestivation shrinks the animal as well as slowing it: the gut wastes away and it loses weight, then rebuilds itself once the sea cools.
Q 25The skeleton of most sea cucumbers is reduced to microscopic ossicles in the skin, made of which mineral?
Calcium carbonate
Calcium carbonate ossicles come in shapes such as tables and buttons that differ between species, so biologists can name a sea cucumber from a scrap of skin under a microscope.
Q 26Round, colourful Pseudocolochirus sea cucumbers, sought after for marine aquariums, are named after which fruit?
Apples
Apples lend their name to these sea apples, which can poison a whole tank with their toxin and swell to nearly twice their size by gulping seawater.
Q 27The deep-sea sea cucumber Psychropotes longicauda, with its upright tail-like lobe, is nicknamed the 'gummy' what?
Squirrel
Squirrel is the comparison that stuck, because the animal looks like a squirrel-shaped gummy sweet. Its eggs, 4.4 mm across, are the largest of any animal in its phylum.
Q 28Holothuria scabra, a tropical sea cucumber widely farmed for food, goes by which misleading common name?
Sandfish
Sandfish burrow into the seabed, and the older animals, which are more sensitive to temperature, dig in to escape the cold.
Q 29Which name did 18th-century English give to sea cucumbers before it passed to a group of molluscs?
Sea slugs
Sea slugs was the name the Oxford English Dictionary records for sea cucumbers in the 1700s, before it passed to the nudibranchs and their kin.
Q 30Compared with a starfish, whose mouth faces the seabed, a sea cucumber spends its life in which position?
Lying on its side
Lying on its side is the normal posture: the mouth is at one end and the anus at the other, so three of its five rows of feet face down and do the walking.