Animals, plants and ecosystems

45 to explore

• Watch Try it What If? Lab What if elephants talked with very low sounds? Elephants really do talk with very low rumbles, some too low for people to hear. Turn the pitch down in our sound model and see what changes about the wave, then find out how far real elephant calls can carry.
• Watch Try it What If? Lab What if fish had no swim bladder? Most bony fish carry a gas-filled pouch called a swim bladder. It makes the fish almost exactly as heavy for its size as the water around it, so it can stay at one depth without sinking or floating up. Use a floating-and-sinking model to see what happens when the gas is taken away.
• Watch What If? Lab What if there were no decomposers? Bacteria, fungi, earthworms and millipedes break down dead leaves, wood and dead plants and animals, and give their nutrients back to the soil. National Geographic calls them Earth's cleanup crew. Imagine a world without them, and follow what might pile up, what might run short, and who does the work.
• Watch What If? Lab What if we could understand animal sounds? Animals pass messages with sounds, smells, movements and touch. Scientists have already worked out what a honey bee's dance means, and they are listening hard to whales. Imagine understanding three animals, a bee, a whale and a dog, and find out how much we really know.
• Watch What If? Lab What if there were no fungi? Fungi are a whole kingdom of living things, with about 144,000 known species, from tiny yeasts to big mushrooms. They puff up our bread, ripen some cheeses, rot dead wood and team up with plant roots. Imagine a world with no fungi at all and follow what might change.
• Watch What If? Lab What if animals did not hibernate? Winter brings two big problems for animals: less food and lots of cold. Bats, groundhogs, dormice and bears get through it by slowing their bodies right down. Imagine they couldn't, and follow what might change for finding food, saving energy and the famous winter sleepers.
• Watch What If? Lab What if a cactus grew in a rainforest? Desert cacti are built to save every drop of water. A rainforest gets rain almost all year. Move a desert cactus into the rainforest and its water-saving tricks could turn into trouble, because soggy soil can make its roots rot. Yet some cacti really do live in rainforests, high up in the trees!
• Watch What If? Lab What if a caterpillar never became a butterfly? A caterpillar is an eating machine. Inside its chrysalis it rebuilds its whole body into a butterfly that can fly, find a mate and lay eggs. Imagine a caterpillar that never changed: what would it miss, and what would happen to the next generation?
• Watch What If? Lab What if a forest grew back after a fire? In 1988, fires passed through about a third of Yellowstone National Park. Today, the young trees that sprouted afterward have grown into new forests. Follow the forest's comeback: the first plants, the pine cones that open with heat, and the animals that return.
• Watch Try it What If? Lab What if a greenhouse got too hot? Plants grow best when it is warm, but not too warm. Heat up a model leaf from a comfortable 25 °C to a scorching 45 °C and watch two things change at once: the leaf makes sugar more slowly, and it burns sugar faster. At some point it burns more than it makes.
• Watch Try it What If? Lab What if a habitat lost its water supply? Water makes plants grow, and plants feed animals. In our model, a dry spell cuts the plant food from 50 tonnes a year to 20, so the land can feed far fewer deer. Watch the herd shrink to fit, then find out how drought affects real wildlife and how people help.
• Watch Try it What If? Lab What if a plant lived in a dark cave? A green leaf makes sugar from light, water and air, but it also uses up a little sugar all the time just to stay alive. Carry our model leaf from bright sunshine into a dim cave and watch what happens when the sugar it makes drops below the sugar it uses.
• Watch What If? Lab What if all flowers were the same color? Flower colors are signals. Bees go for blue and yellow, hummingbirds for red, and night-flying moths for white. Imagine a world where every flower was the same color: how would pollinators find the right flowers, and what might happen to the plants?
• Watch What If? Lab What if an invasive species entered an ecosystem? An invasive species is a living thing that ends up somewhere it doesn't naturally live and causes harm there. In this thought experiment, follow two real stories from Australia: cane toads, brought to eat beetles in sugar cane fields in 1935, and rabbits, which probably spread mostly from 24 brought in 1859. Then find out how people try to keep ecosystems in balance.
• Watch Try it What If? Lab What if animal populations grew beyond available food? Land can only feed so many animals. In our model, a herd of deer grows until it nears that number. But what if the deer react to crowding late? Watch the herd shoot past what the food can feed, then fall back, and meet real herds that did the same.
• Watch What If? Lab What if animals could change color like an octopus? Octopuses and cuttlefish change the color and texture of their skin in the blink of an eye, using thousands of tiny color cells. They use it to hide and to send signals. Imagine if many more animals could do it: who would hide better, what would they say with color, and what would it cost them?
• Watch What If? Lab What if ants left no trails? Many ants mark the way to food with a scent trail, and their nestmates follow it. Because old scent fades, the colony often ends up on the shortest path. Computer scientists even copy the trick. Imagine ants that left no trails and follow what might change.
• Watch Try it What If? Lab What if beavers built no dams? Beavers eat willow and aspen, and they also build dams that turn streams into ponds. Take the beaver out of our forest food web and the model finds only one change. Then find out why scientists call beavers nature's engineers, and what a food web leaves out.
• Watch Try it What If? Lab What if bees disappeared? Many fruits and vegetables only grow well when bees and other animals carry pollen between their flowers. In our model farm, turn the pollinators down to zero and watch which harvests shrink, which hardly change, and why wheat, rice and corn don't mind. Then meet the people helping pollinators.
• Watch What If? Lab What if birds forgot how to build nests? Nests keep eggs and chicks safe from predators and the weather, and birds build them in amazing ways: from twigs, grass, mud, hair and even spider silk. Imagine every bird forgetting how to build one. Then meet the birds that already manage without, from cliff-ledge murres to emperor penguins.
• Watch What If? Lab What if cats had no whiskers? A cat's whiskers are not just for looks. They are touch sensors that feel air moving, things brushing past, and the edges of gaps. Imagine a cat with no whiskers: how would it find its way in the dark or know if it fits through a hole?
• Watch What If? Lab What if cows could not digest grass? A cow's own body can't break down the tough stuff in grass. Tiny microbes living in its huge stomach do it instead, and the cow chews its food twice to help them. Imagine those helpers gone and follow what might change.
• Watch What If? Lab What if dinosaurs still lived today? Most dinosaurs died out 66 million years ago, after a huge asteroid hit Earth. One group survived: birds, which scientists count as living dinosaurs. Imagine the other dinosaurs had survived too. Where could they live, what would they eat, and how would they fit into today's world?
• Watch What If? Lab What if elephants stopped shaping the savanna? African elephants change the land around them. They feed on and push over trees, dig wells in dry riverbeds that other animals drink from, and carry seeds farther than almost any other land animal. Imagine elephants stopped doing all that: how might the savanna change?
• Watch What If? Lab What if every animal slept at night? Night is busy. Barn owls hunt by sound in the dark, moths and bats take over the night shift of pollination, and fennec foxes leave their burrows once the hottest hours have passed. Imagine every animal sleeping at night: who would go hungry, who would overheat, and what jobs would be left undone?
• Watch What If? Lab What if every animal were the same size? The smallest bird weighs less than 2 grams; a big elephant weighs more than three million times as much. Size decides what an animal can eat, how it keeps warm and how fast its body runs. Imagine every animal squeezed or stretched to one size, and see what would go wrong.
• Watch What If? Lab What if forests became grasslands? Forests and grasslands are next-door neighbors in many places, and fire, grazing animals and rain decide where one ends and the other begins. Imagine a forest becoming a grassland: who would move in, what would happen to the soil, and where would all the carbon in the trees go?
• Watch Try it What If? Lab What if foxes became better hunters? In a meadow model, rabbits and foxes rise and fall in turns. Make every fox twice as good at catching rabbits and you might expect a meadow full of well-fed foxes. The model says the opposite: in the long run there are fewer foxes, not more. Find out why, and how real predators and prey compare.
• Watch What If? Lab What if honeybees could not dance? When a honeybee finds great flowers, she flies home and dances on the honeycomb. The dance tells other bees which way to fly and how far. Scientists have even tested hives where the dance can't point the way. Imagine bees that could not dance and follow what might change.
• Watch Try it What If? Lab What if insects vanished? Insects eat plants, and birds, mice and bears eat insects. In our forest food web, take the insects out and see who could go hungry and who could change. Then find out why scientists are counting insects carefully, and how people help them.
• Watch What If? Lab What if migratory animals couldn’t reach their destinations? Every year, birds, butterflies, deer and pronghorn travel huge distances between their summer and winter homes. Along the way they need stopover places to eat and rest, and clear paths across the land. Imagine those stops disappearing or those paths blocked by roads and fences, then meet the wildlife bridges and protected places that help animals travel.
• Watch What If? Lab What if mosquitoes disappeared? Nobody enjoys an itchy mosquito bite. But mosquitoes are also food for fish, dragonflies, birds and bats, and some even pollinate flowers. Some kinds can also carry germs that make people sick. Imagine every mosquito gone: what would we gain, what might we lose, and why aren't scientists sure?
• Watch What If? Lab What if penguins could fly? Penguins are birds whose wings became stiff flippers for swimming. Their ancestors flew, but today's penguins are superb divers instead. Imagine a penguin that could fly: what would it need to change, and what might it lose underwater?
• Watch What If? Lab What if plants ate insects everywhere? Carnivorous plants catch insects to get nutrients their soggy, poor soil can't give them. They still make food from sunlight. Imagine if every plant everywhere caught insects: would it help them, and why do so few plants bother?
• Watch What If? Lab What if plants could walk? A plant can't get up and walk to a sunnier spot or a new home. Instead, its seeds travel by wind, water and animals, its roots hold it firmly in the ground, and its stems and leaves slowly turn and bend. Imagine a walking plant: what would it gain, and what would it give up?
• Watch What If? Lab What if plants glowed in the dark? Some living things make their own light: fireflies, a few kinds of mushrooms, and many animals in the deep sea. It's called bioluminescence. Garden plants don't glow, but scientists have now made a few plants that do. Imagine a world of glowing plants: how bright would it be, and what might it change?
• Watch Try it What If? Lab What if plants had more carbon dioxide? Leaves build sugar out of carbon dioxide from the air, using the energy in light. Some greenhouse growers add extra carbon dioxide on purpose. Raise the carbon dioxide around a model leaf from today's level to more than double and see how much faster it makes sugar, and why it soon stops helping as much.
• Watch Try it What If? Lab What if plants received less light? Green leaves use light to turn water and carbon dioxide into sugar, their food. In our model leaf, cut the light to a quarter and watch how much sugar it still makes, then find out how some forest trees manage to live in deep shade.
• Watch Try it What If? Lab What if rabbits had more babies? Rabbits are famous for having lots of babies. So if every rabbit in a meadow had babies twice as fast, you would expect a meadow full of rabbits. In our rabbit and fox model, something surprising happens instead: the extra rabbits mostly end up feeding more foxes.
• Watch What If? Lab What if seeds could not travel? Seeds ride the wind, float on water, hide in fruit that animals eat, and cling to fur and socks. What if every seed simply dropped under its parent plant? Explore crowded seedlings, wind and animal helpers, and the burrs that gave people an idea.
• Watch Try it What If? Lab What if there were no predators? In a meadow, rabbits have babies and foxes hunt them, so both numbers rise and fall in turns. Take every fox away in our model and watch what the rabbits do, then find out what happened in a real park when its wolves were taken away and brought back.
• Watch What If? Lab What if there were no spiders? Spiders around the world catch an estimated 400 to 800 million tons of prey every year, mostly insects. They also spin some of the toughest materials in nature. Imagine a world with no spiders: what would happen to all those insects, and what would we lose?
• Watch What If? Lab What if trees never lost their leaves? Every autumn, maples, birches and many other trees drop their broad leaves, while pines and spruces stay green. Imagine broad-leaved trees keeping their leaves all winter: what would happen to their water, to their branches in a snowstorm, and to the bright autumn colors?
• Watch What If? Lab What if trees shared food underground? Almost every tree has a fungus partner living on its roots. The fungus brings water and minerals; the tree pays it in sugar. Some people say the fungi also link trees together so they can share food. Explore what scientists have measured, and why some of them say the 'sharing' story has gone further than the evidence.
• Watch Try it What If? Lab What if wolves returned to a park? For nearly 70 years, Yellowstone National Park had no wolf packs. In 1995, people brought wolves back. Start with a model park that has no wolves, put the wolves back into its food web, and see what changes for the elk, the willows and the animals that need them. Then find out what scientists in the real park are still working out.