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Generally speaking, plants and animals aren't huge fans of fire. The intense heat can damage living tissues and the smoke can irritate eyes and lungs. Not to mention the damage that a large fire can do to an organism's habitat. But it might surprise you to learn that there are some species that have turned fire into a friend. These plants and animals not only tolerate the flames, they thrive alongside them. My name is Johnny, and you're watching SciShow.
[♪ INTRO] To meet our first fire-loving species, you'll have to take a trip to the fynbos shrublands of southern Africa. There, if you're lucky, you'll spot a grove of beautiful flowers called fire lilies. At first, you might think the name just refers to their striking orange-red color, but it's more than that. These incredible flowers only appear after a fire. Wildfires are pretty common in this environment, and many of the local plants are really good at bouncing back after a fiery disturbance. But fire lilies, a species named Cyrtanthus ventricosus,
don't just survive fire, they rely on it. Fire lily bulbs sit dormant in the soil until conditions are right for them to grow. But the fire lilies aren't waiting for just any conditions, they're waiting for fire. These bulbs might remain dormant for over a decade, and only after a wildfire scorches the land above them will they finally grow, emerging from the ash like a baby phoenix. And when they do, they grow really fast. These flowers go from bulb to full bloom in just seven to nine days after a fire! This rapid growth is possible thanks in part to the flowers' hollow stem, which is sturdy but light on structural material. So if you do discover a grove of fire lilies,
you can be sure that a fire came through about a week earlier. But of course, the flowers wouldn't be the only evidence of a fire. The surrounding landscape would be full of burnt and dead plants. And that's exactly how the fire lilies like it. The main benefit of blooming after a fire is that all the other plants have been destroyed, giving the flowers unimpeded access to lots of sunlight and soil nutrients. On top of that, a field of bright flowers in an ashy landscape is super easy to see for animals like birds and butterflies, which are essential for the flowers' reproduction.
So it's pretty easy to see why fire lilies bloom right after a fire, but how they do it is more mysterious. Something about the fire is acting as a trigger for the bulbs to flower, and evidence suggests it's not the flames themselves, but the smoke. Many scientists suspect the culprit is ethylene gas, which is used by many plants to regulate their growth and development, but studies have found conflicting evidence for this. It's also possible that the bulbs are reacting to the heat or light from the fire, or a combination of some or all of these factors. Because of their beauty and their hardiness,
many people have tried to cultivate fire lilies, but they haven't had much success. As you might expect, flowers that require fire to grow are kinda tough to manage in your garden. Here in North America, fires aren't followed by blooms of fire lilies, but they are often accompanied by swarms of fire beetles. Insects, like plants, tend to be pretty flammable. So when bugs sense the heat or smoke from a fire, they usually get out of dodge. But beetles of the species Melanophila acuminata do the opposite - they fly towards the flames.
This behavior is so common, and the beetles are so widespread, that if there's a wildfire almost anywhere across the Northern Hemisphere, there's an excellent chance there will be fire beetles there. But the beetles aren't seeking to go out in a literal blaze of glory… They're looking for love. Wildfires serve as meeting places for these bugs to congregate, find a mate, and get intimate in the glow of the firelight. Who says insects can't be romantic? It turns out a fire is a pretty good place to mate. Not only do the flames create an easy-to-find meeting spot, they also keep away lots of predators and competitors who have the good sense to avoid the fire. And once mating is done and the fire dies down,
the beetles are left with an excellent nursery for their babies. They lay their eggs in the freshly burned bark of trees and shrubs, and when those eggs hatch, the little grubs make a meal out of the weakened plant tissues and the fungi growing on the dead wood. Fires can even speed up the beetles' development. Normally, it takes about a year to go from newly laid eggs to fully developed, pupating larvae. But one study reported that beetles developing in recently burned wood could grow up in just two months! Small pits on the underside of the beetles' thorax are extra-sensitive to heat.
These heat-sensors might be helpful for zeroing in on a fire, but also probably help the beetles keep a close eye - or pit - on changes in fire behavior while they're busy finding mates and laying eggs. That way they don't get caught by a sudden flare-up of flames. Besides their heat-sensing organs, the beetles can probably also detect smoke with their antennae and use their eyes to scout for flames on the wing. Using these tools, they can travel many miles to gather at a fire. Their attraction to fire is so strong that they've been known to swarm at lumber yards, smelting plants, and even at burning buildings, where they can be a real pain for evacuees and
firefighters - not only because of their loud buzzing, but also their painful bites. One report from the 1940s describes swarms of fire beetles hanging around football games at the University of California Berkeley, possibly attracted by the cigarette smoke from the crowd! Those fire bugs have a pretty good hustle going on - mate and grow where most other animals don't even want to be. But some species are wise to their tricks, like North American black-backed woodpeckers. These birds range all across the northern parts of the continent, but they live almost exclusively in areas that have recently experienced severe fires.
One study in the northwestern United States counted almost 200 sightings of these woodpeckers, and all but six were in burned forests. These birds don't just like burned forests, they specialize in living there. Just like the fire beetles, the woodpeckers are probably taking advantage of the general lack of predators and competition in the wake of a forest fire. But while the bugs are feeding on the dead plants, the woodpeckers are feeding on the bugs! Thanks to the reproductive habits of all those fire-loving insects, the wood of burned trees is full of delicious grubs.
And woodpeckers are experts at getting bugs out of bark. As scientists continue to study these environments, it's becoming clear that burned habitats support unique and complex ecosystems all their own. This is really valuable knowledge for conservation and wildlife management. It's easy to think of a burned forest as a destroyed habitat, but in reality, it's just a different one. But before we get to the rest of our dedicated fire-lovers, let's go to a quick break. Thanks for watching SciShow and learning new science stuff with us! After all, learning doesn't just have to happen in school.
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Click the link below or scan the QR code to try Brilliant for free. You can upgrade to Premium to unlock all courses. And right now, SciShow viewers can save 20% off an annual subscription at brilliant.org/scishow. Clearly, living life in the aftermath of a fire is a winning strategy for lots of plants and animals. But some clever predators have found that the best time to go hunting is while the fire is still burning. For a long time, naturalists around the world have noticed that a wildfire is an especially good place to spot predatory birds.
Here in North America, for example, one study observed bird activity during 25 fires in Oklahoma in 2013 and 2014. They found that one particular species, Swainson's Hawks, seemed to really like hanging out around the fires. At times, these birds could be seven times more abundant during fires compared to before and after them. And they weren't just hanging around to enjoy the heat - they were hunting. While animals are running from a fire, they're not hiding from predators. During those Oklahoma fires, the hawks were seen snatching up rodents and lizards that were either flushed out by the flames or injured by them. That study referred to this behavior as pyric carnivory - actively hunting around fire.
But Swainson's hawks aren't the only ones. That study also noted species like red-tailed hawks and Mississippi kites gathering to hunt near the fire. And other species around the world have shown similar behaviors. Meanwhile, other birds, like storks and buzzards, have been known to follow behind fires, picking off dead or injured prey left behind by the blaze. For these predators, the devastation of a fire can save them a lot of time and effort they'd otherwise spend seeking, and chasing prey. And some birds have even been reported to intentionally spread fires.
All across northern Australia, there have long been reports of kites and falcons flying into active fires, where they pick up burning sticks and then fly off to drop them somewhere else, thereby spreading the flames and flushing out even more prey. So far, there haven't been any scientific studies that have directly documented this fire-spreading activity, so the details are unclear. But this behavior is widely known to Indigenous communities in the region, and people who manage brush fires are often wary of birds that might carry flames to new areas. Firefighters really can't catch a break this episode. So far, we've mentioned plants and animals that thrive in the aftermath of a fire,
and some that even take advantage of the chaos during a fire. But the last entry on our list is a group of life that makes its living being fuel for fire. And this isn't some obscure lifeform… It's grass. Many grasses live humble lives in small patches on the forest floor or poking out of a sidewalk. But some are far from humble, forming massive grasslands that stretch to the horizon, some of the most extensive biomes on our planet. And these grasslands exist because of fire. In fact, without fire, our world would have a lot less grass and a lot more trees.
Grasses tend to do pretty well with fire. They're just as flammable as other plants, but they grow very quickly, so they can bounce right back after a fire. Trees, on the other hand, are slower to rebound. So grasslands are especially successful in fire-prone regions, especially in parts of Africa and South America. With such regular fires, forests don't get the chance to grow, and grasslands take over. But the opposite is also true. In regions where humans have suppressed natural fires, grasslands are gradually replaced by forests.
This relationship between fire and foliage is thought to be a major reason why the Earth is so grassy. See, grasslands are a pretty young feature of our planet. Fossil evidence shows that they only started to spread widely about eight million years ago. At the same time, the fossil record also shows a significant increase in burned plant remains. This environmental shift is related to the climate. During this time period, the Earth experienced the onset of monsoon-style climate patterns, creating habitats with distinct wet and dry seasons, and that's great for fire.
Plants grow profusely during the wet season, and when they dry out or die off in the dry season, they create lots of fuel, which clears space for more growth in the next wet season. As this climate pattern became more common, ancient forests were replaced with the hot new thing: grasslands. One study in 2004 ran a simulation that modeled the relationships between vegetation growth, climate conditions, and fire regimes around the world. When the simulation mimicked modern-day environmental conditions, it predicted grasslands and forests pretty much where we have them in the real world, as expected. But when they removed fire from the equation,
they found that more than half of the world's grasslands were overtaken by forest. The conclusion: without fire, we'd have a lot less grassland. Without grassland, we'd have a lot fewer species that evolved to live there, including big herbivores like horses and bison, and their predators like lions and wolves. Not to mention … us! A lot of the grasslands that disappeared in those "fire off" simulations were in Africa. And the spread of those grasslands in particular is thought to have been a major factor that
encouraged our ancestors to move out of the forests and into more open, grassy habitats. Long before we learned to wield it for ourselves, fire played a crucial role in setting the stage for the evolution of our own species! [♪ OUTRO]
