Vertebrates
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50 free Vertebrates trivia questions with answers — trivia quiz, new questions added Oct 2026.
Vertebrates are the animals with a backbone: fish, amphibians, reptiles, birds and mammals, humans included. They make up only a small share of all animal species, yet they include the biggest, fastest and longest-lived creatures on the planet. This quiz opens with the surprising record holders and oddities, then works through what an introductory biology unit covers: how the five classes differ, how they breathe, reproduce and keep warm, the bones and organs they share, and the fossils that connect one group to the next. A few questions cover the naturalists who first sorted these animals into groups. It suits students revising for a science test, teachers who want a ready-made multiple-choice round, and anyone curious about the animal kingdom. Every answer comes with a short explanation.
30 of 50 questions with answers and explanations. Play the quiz
Q 01Nearly all mammals, even giraffes, have seven neck vertebrae; which tree-dwellers are a rare exception?
Sloths
Sloths break the mammal rule: two-toed kinds have five or six neck vertebrae and three-toed kinds have nine. The only other known exception is the manatee, with six.
Q 02Which Australian mammal lays eggs, has webbed feet and a duck-like bill, and carries venomous ankle spurs if male?
Platypus
The platypus is one of only five living monotremes, the mammals that lay eggs; the other four are echidnas. A male's venom is strong enough to cause people severe pain.
Q 03Which sluggish fish can live for at least 270 years, longer than any other known vertebrate?
Greenland shark
The Greenland shark is aged by radiocarbon dating the lenses of its eyes, and the oldest one measured was put at roughly 390 years. It may not be ready to breed until about 150.
Q 04Which mammals, about a fifth of all mammal species, are the only ones capable of sustained flight rather than gliding?
Bats
Bats fly on a thin membrane stretched across long, spread-out fingers, which makes them more agile in the air than most birds. At least 1,500 species are known.
Q 05Which sea mammal, weighing up to about 190 tonnes, is the largest animal known ever to have existed?
Blue whale
The blue whale reaches about 30 metres in length, yet it feeds almost entirely on krill. It lunges at a swarm with its mouth wide open, then strains the water out through baleen plates.
Q 06Which living reptiles are the closest relatives of birds, the two groups being the only surviving archosaurs?
Crocodilians
Crocodilians also parent more like birds than lizards: they are unusual among reptiles in how much care they give their young after the eggs hatch.
Q 07Which Mexican salamander keeps its external gills for life and never leaves the water to live on land?
Axolotl
The axolotl can regrow lost limbs, gills and even parts of its brain without scarring. In the wild it is now limited to Lake Xochimilco, a remnant of canals hemmed in by Mexico City.
Q 08Which bird of prey is widely called the fastest animal on Earth because of its steep hunting dive, the stoop?
Peregrine falcon
The peregrine falcon is often credited with dives of over 320 km/h, though the highest speed reliably tracked by radar is 184 km/h. It soars to a great height, then drops steeply onto its prey.
Q 09Dolphins and porpoises evolved from land mammals; which pig-like living animal is their closest relative?
Hippopotamus
The hippopotamus and the cetaceans share an ancestor from which they split about 55 million years ago. Blood proteins, DNA and fossils all point to the same family tie.
Q 10Which birds can swivel their heads about 270 degrees, helped by having 14 neck vertebrae, twice as many as humans?
Owls
Owls have eyes fixed in bony tubes, so they cannot glance sideways and must turn the whole head instead. Extra-wide channels in the neck bones keep blood flowing to the brain as it twists.
Q 11Which flightless bird, the largest alive, lays the biggest eggs of any living bird and can sprint at about 70 km/h?
Ostrich
The ostrich is also the fastest animal on two legs, covering up to five metres in a single stride. Only extinct giants such as Madagascar's elephant bird laid bigger eggs.
Q 12Which Indonesian reptile, growing up to three metres long, is the largest living species of lizard?
Komodo dragon
The Komodo dragon lives wild on only a handful of Indonesian islands, among them Komodo, Rinca and Flores. The biggest males can weigh as much as 150 kg.
Q 13Which nectar-feeding birds of the Americas can hover and fly in any direction on wings beating up to 99 times a second?
Hummingbirds
Q 21Birds are the only living members of which group of reptiles, long believed to have died out 66 million years ago?
Dinosaurs
Dinosaurs live on as birds, which evolved from the two-legged theropods. The mass extinction that ended every other branch also killed off the flying pterosaurs.
Q 22Which reptiles have backbones of 200 to 400 vertebrae or more, far outnumbering the 33 found in a human?
Snakes
Snakes have ribs along almost the whole body, because nearly every vertebra in front of the short tail is built like a chest vertebra. Only a few neck bones go without.
Q 23Which reptiles have ribs that grow sideways into broad bony plates, leaving the shoulder blades inside the rib cage?
Turtles
Hummingbirds include the bee hummingbird, the world's smallest bird at about 2 grams. The hum that gives the family its name is the sound of those rapidly beating wings.
Q 14Which bird breeds during the Antarctic winter, the male balancing a single egg on his feet for about two months?
Emperor penguin
The emperor penguin male eats nothing while he guards the egg and loses around 12 kg before it hatches. The female spends those weeks feeding at sea.
Q 15Kangaroos, koalas and opossums belong to which mammal group, whose tiny newborns usually finish growing in a pouch?
Marsupials
Marsupials are not only Australian: about 30 percent of the species live in the Americas, though the Virginia opossum is the only one found north of Mexico.
Q 16Which order of gnawing mammals, from tiny mice to the capybara, makes up about 40 percent of all mammal species?
Rodents
Rodents are set apart by pairs of sharp incisors that never stop growing, which they use to gnaw food, dig burrows and defend themselves. Most species weigh less than 100 grams.
Q 17Which process, driven by the hormone thyroxin, turns a legless tadpole into a four-legged adult frog?
Metamorphosis
Metamorphosis does not shed the tadpole's tail: the tail is absorbed back into the body through programmed cell death. Lungs for breathing air develop along the way.
Q 18Skates and stingrays have boneless skeletons made of which tough, elastic tissue that also shapes the human nose?
Cartilage
Cartilage is the main skeletal tissue of every vertebrate early in development, and in most it is later largely replaced by bone. Skates and their kin simply never make the switch.
Q 19Which bundle of nerves, about 45 cm long in adult humans, is protected by a canal running through the vertebrae?
Spinal cord
The spinal cord does more than relay messages: it contains reflex arcs that can control some reflexes independently, without waiting for the brain.
Q 20Which organ has two chambers in fish, three in amphibians and four in birds and mammals?
Heart
The heart of a fish is a single pump that sends blood once through the gills and straight on to the body. Birds and mammals have two pumps in one, with four chambers in total.
Turtles can never leave their shells, because the upper shell, or carapace, is fused to the ribs and backbone. Even the hip bones sit inside it.
Q 24Which fish hatch in fresh water, grow up at sea, then return to the stream of their birth to spawn?
Salmon
Salmon find their home stream so reliably that tracking studies have shown the old folklore to be mostly true, though a share of every run strays to spawn elsewhere.
Q 25Which South American river fish, a knifefish despite its common name, can stun prey with shocks of up to 860 volts?
Electric eel
The electric eel must also rise to the surface to breathe air, which lets it live in water low in oxygen. Its main organ alone can discharge at least 600 volts.
Q 26Which fish, thought extinct for over 60 million years, turned up alive off South Africa in 1938?
Coelacanth
The coelacanth has fleshy, lobed fins and is more closely related to four-legged land animals than to most other fish. Its return made it the best-known Lazarus taxon, a lineage that reappears after vanishing from the fossil record.
Q 27Which jawless fish, the only living animals with a skull but no vertebral column, fend off predators with slime?
Hagfish
Hagfish slime clogs an attacker's gills, and the hagfish then cleans itself by tying its body into a knot and sliding the knot from head to tail.
Q 28Which forked bone, usually formed from two fused collarbones, braces a bird's chest against the strain of flight?
Wishbone
The wishbone also works like a spring, flexing between the shoulders in flight, as films of flying starlings have shown. Its formal name, furcula, is Latin for little fork.
Q 29Birds have no teeth, so which thick-walled, muscular part of the stomach grinds their food, often with swallowed grit?
Gizzard
The gizzard does the chewing that a toothless bird cannot, crushing food against swallowed stones. It can also pass a meal back to the true stomach and take it in again.
Q 30Lungless salamanders, the largest family of salamanders, have no lungs and take in oxygen mainly through which organ?
Skin
Skin is a major breathing surface in every amphibian that has been measured, not only the lungless ones. Oxygen passes straight through it into the blood.