50 Fun Facts About Food Chains and Food Webs

Blue whales, the largest animals ever known, feed almost entirely on which swarming crustaceans?

Krill make up almost the whole diet of the blue whale, which lunges into a swarm at speed with its mouth gaping up to 80 degrees and strains them from the water.

Giant pandas belong to the meat-eating order Carnivora, yet about 99% of their diet is which plant?

Bamboo gives a giant panda little energy, because the animal still has the short, straight gut of a carnivore and so has to eat enormous amounts of it.

Which bog plant, native only to the Carolinas, flips the food chain by snapping shut on insects?

The Venus flytrap shuts only when two of its trigger hairs are touched within about twenty seconds, a check that stops it wasting effort on raindrops.

Which mammal guards Pacific kelp forests by eating the sea urchins that graze them bare?

Sea otters eat so many sea urchins that their teeth and bones can be stained purple, and where they vanish the urchins can mow whole kelp forests down.

Which predators, back in Yellowstone since 1995 after nearly seventy years away, prey mainly on elk?

Gray wolves were released in the Lamar Valley, and as their packs grew the elk herds shrank, easing the browsing pressure on the willows and aspens.

Which ocean predator, hunted by nothing itself, flips great white sharks over to eat their livers?

The killer whale rolls a great white onto its back, which sends the shark into a paralysis called tonic immobility, and then goes for the liver.

Which scavenging birds have stomach acid that can destroy the anthrax and botulism in rotten meat?

Vultures digest putrid meat in stomach acid of about pH 1, which lets them clean up infected carcasses that would be lethal to other scavengers.

Owls swallow mice whole and later cough up the fur and bones as what, often dissected in school?

Pellets hold the fur, bones and teeth an owl cannot digest, so picking one apart reveals exactly what the bird has been feeding on without harming it.

Which popular pet is an obligate carnivore, needing meat because it cannot make enough taurine?

The domestic cat cannot make enough taurine, and heart disease was common in cats fed commercial diets until a 1987 study traced it to a lack of that nutrient.

Koalas sleep up to twenty hours a day on a diet of the low-energy leaves of which tree?

Eucalyptus leaves are low in calories and contain toxins that put off most other mammals, which leaves koalas with a food supply few rivals want.

Almost every food chain on Earth, from pond to coral reef, gets its energy originally from where?

The Sun powers almost every food chain, yet plants capture only about one percent of the light that reaches them, and all animal life runs on that sliver.

Which name do ecologists give plants and algae, which start a food chain by making their own food?

Producers build their own food from light, air and water, so every animal in a food chain, even a lion that never touches a leaf, depends on them in the end.

Which food web role do soil bacteria fill by breaking dead plants and animals down into nutrients?

Decomposers return the nutrients locked in dead leaves, wood and bodies to the soil, where roots can take them up again and the cycle restarts.

Which term describes a tiger, a saltwater crocodile or any hunter at the top of its food chain?

Apex predator is the label for a hunter with few or no natural enemies, and by keeping prey and smaller hunters in check such animals can reshape a whole ecosystem.

Which process lets green plants turn light, water and carbon dioxide into sugar and oxygen?

Photosynthesis was discovered in 1779 by Jan Ingenhousz, who showed that plants need light, and not just soil and water, in order to grow.

On average, about what share of the energy in one link of a food chain passes on to the next link?

Only about 10% of the energy moves up each time, which is why a field of grass can feed many rabbits but those rabbits can feed only a few foxes.

In a food chain drawn as grass, then rabbit, then fox, each arrow stands for which phrase?

Is eaten by is how to read every arrow, because the arrowhead follows the energy as it leaves the food and enters the animal that swallows it.

Which shape do ecologists use to show each step of a food chain holding less energy than the last?

A pyramid fits because the broad base of plants supports ever narrower layers of animals above, and one drawn for energy can never be turned upside down.

Most energy an animal eats never reaches the next link in a food chain, leaving mainly as what?

Heat carries the energy away, given off as the animal's cells burn food to keep it moving, growing and alive, so it can never be passed up the chain.

In the food chain grass, grasshopper, frog, the insect-eating frog is which kind of consumer?

Secondary is the label for any animal that eats plant-eaters, and a snake that then swallowed the frog would sit one rung further up.

Which drifting organisms, too small to see, feed most ocean life and make half of Earth's oxygen?

Phytoplankton do about half of all the planet's food-making despite adding up to only about 1% of its plant mass, and nearly every ocean food web rests on them.

Which toxic metal climbs ocean food chains, which is why pregnant women are told to avoid swordfish?

Mercury is taken up by algae and handed on with every meal, so shark meat can hold more than ten times the concentration found in herring.

Which insecticide, building up in food chains, thinned bald eagle eggshells until a 1972 US ban?

DDT built up in the birds' prey, and their eggshells grew so thin that they often cracked before the chicks could hatch.

Monarch caterpillars eat only which plant, storing its toxins to make themselves poisonous to birds?

Milkweed sap is laced with heart poisons that the caterpillars store in their bodies, and their bright colors warn hunters of the foul taste.

Which insects, sacred in ancient Egypt, steer by the Milky Way while rolling away a ball of food?

Dung beetles bury and eat the droppings of larger animals, which returns nutrients to the soil, and one African species holds its course at night by the galaxy's glow.

Which kingdom of life does most of the work of rotting a fallen tree on the forest floor?

Fungi digest their food outside their bodies, threading fine hyphae deep into dead wood that bacteria can only work on from the surface.

Which soil animals, the subject of Charles Darwin's last book, drag dead leaves into burrows to eat?

Earthworms so fascinated Darwin that he made a trip to Stonehenge to see how far their castings had buried its fallen stones.

Grizzly bears have a carnivore's gut, but a diet of nuts, tubers, moths and meat makes them what?

Omnivores eat both plants and animals, and in Yellowstone a grizzly's menu is mostly pine nuts, tubers, grasses, rodents and moths.

Which bird of prey, the fastest animal on Earth in a dive, feeds almost entirely on other birds?

The peregrine falcon strikes its prey in mid-air after a dive of more than 320 km/h, and its menu runs from pigeons and ducks to songbirds and parrots.

Which reef fish scrape algae off coral rock and excrete it as the white sand of tropical beaches?

Parrotfish grind up the rock along with the algae between a second set of teeth in the throat, and the sand they pass helps to build beaches and small islands.

Which term, from a Greek word for nourishment, names each feeding step in a food chain?

Trophic level 1 holds the plants and level 2 the animals that eat them, and the count typically tops out with the fiercest hunters at level 4 or 5.

Robert Paine coined which term in 1969 for an animal whose removal reshapes its whole food web?

Keystone species take their name from the central stone of an arch, which bears the least pressure of any stone and yet brings the whole arch down if it is removed.

Which term describes a poison becoming more concentrated at each step up a food chain?

Biomagnification means a top hunter can carry far more of a pollutant than the water around it, because every meal adds the load stored by everything lower down.

Which pigment makes leaves green and captures the energy that plants turn into food?

Chlorophyll soaks up red and blue light and bounces back the wavelengths in between, which is why a leaf looks the way it does to our eyes.

Polar bears wait beside breathing holes in Arctic sea ice to ambush which animals, their main prey?

Ringed seals are the commonest catch because they are abundant and small enough for even a small bear to overpower, and bears also break into the lairs where pups are hidden.

Flamingos turn pink from pigments in algae and which small crustaceans they sieve from lakes?

Brine shrimp and algae are rich in carotenoids, which a flamingo's liver breaks down into the pigments laid into its feathers, and zoo birds turn pale without them.

The king cobra of Asia, placed in the genus Ophiophagus, hunts mainly which kind of prey?

Other snakes, including Indian cobras, kraits and even pythons, make up most of its diet, and it will eat smaller members of its own kind.

Which amphibian, released in Australia in 1935 to eat crop pests, poisons the predators that eat it?

The cane toad never did control the pests it was brought in to eat, while quolls, goannas and other native hunters that swallow one are killed by its poison.

Which African carnivore, often dismissed as a scavenger, in fact kills most of its own food?

The spotted hyena hunts for somewhere between half and 98% of its meals, and lions steal its kills more often than it steals theirs.

Which plates of fingernail-like keratin do toothless whales use to strain small prey from seawater?

Baleen works like a sieve: the whale gulps a mouthful, then pushes the water out through the plates and swallows the food left behind.

Deep-sea vent bacteria feed food chains by making sugar from hydrogen sulfide in which process?

Chemosynthesis explains the giant tube worms that the submersible Alvin found in 1977 around seabed vents on the Galapagos Rift, far beyond the reach of daylight.

Which tide-pool predators did Robert Paine remove from Washington rocks, letting mussels take over?

Starfish had been keeping the mussels in check, and within three years of their removal the pools' fifteen rock-clinging species had dwindled to eight.

Decades of fur-trade records show Canada lynx numbers rising and falling in step with which prey?

The snowshoe hare is the lynx's main prey, and their linked booms and crashes have made it a textbook case for biology students around the world.

A 2013 study of diets worldwide ranked humans beside pigs and which fish on the food chain?

Anchovies and humans both score about 2.21 on a scale that puts plants at 1 and meat-eaters at 3 and above, since most of what people eat is plants.

Which fish, dragged ashore by bears and eagles, carry ocean nitrogen into riverside forests?

Salmon fatten at sea, swim upriver to spawn and die, and the half-finished carcasses left on the banks feed the trees with nutrients gathered in the ocean.

Which 1962 Rachel Carson book warned that pesticides were climbing food chains and killing birds?

Silent Spring took its title from a poem by John Keats, and the chemical industry fought hard against the book in the weeks before it went on sale.

Which name did explorer William Beebe give the shower of dead plankton that feeds the deep sea?

Marine snow can sink for weeks before it touches the seabed, and most of it is consumed on the way down, within the first 1,000 metres.

Which fish, released into Lake Victoria in the 1950s, drove hundreds of native species to the brink?

The Nile perch fed first on the lake's native cichlids, and as they ran short it switched to smaller prey such as minnows.

Which Oxford zoologist's 1927 book Animal Ecology set out the modern idea of the food chain?

Charles Elton surveyed Arctic wildlife on Spitsbergen while still a student, and in 1932 he founded Oxford's Bureau of Animal Population to track rises and falls in animal numbers.

Which ecologist's study of Minnesota's Cedar Bog Lake showed how little energy climbs a food chain?

Raymond Lindeman died at 26, and his paper was at first rejected as too sweeping, reaching print only after colleagues talked the journal's editor round.