While some bats indeed suck blood and others carry viruses like COVID-19, we couldn't live without them. Pollinating hundreds of plant species and dispersing their seeds, bats are central cogs in diverse ecosystems.
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Bats have been mythologized for millennia as mystical, elusive and sometimes satanic creatures of the night. Indeed, the cave-dwelling superhero Batman is said to have been inspired by the Mayan "death bat," an animal god of darkness and sacrifice known as Camazotz.
This image has become more sinister in recent times as bats are said to be the source of zoonotic diseases such as Ebola, SARS and now COVID-19. But researchers say humans are the real culprits since they're destroying habitats and biodiversity that once insulated people from pathogens carried by animals.
Without the 1,400-odd species of bats that pollinate more plants across the planet than any other animal, biodiversity will continue to decline and the risk of disease increase.
No bananas without bats
Bats constitute 20% of all mammals on Earth. Without them, many ecosystems would collapse. It's bats, not the birds and the bees that pollinate flowers in vital food-producing plant species like banana, mango and agave. Bats also disperse and regenerate over 500 types of plants, including cacao beans, as they feed on fruits and spit seeds on the ground to germinate.
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But as they begin their migratory journeys across whole continents every spring, bat roosting habitats from Zambia to Germany continue to dwindle due to deforestation and development. Despite the fact that they do well finding hang-outs in buildings and parks in urban areas, their vast numbers are starting to dwindle. There were once some 200 species of flying fox or fruit bats, but eight are now extinct and another 22 are endangered. Fewer bats will lead to less biodiversity – and fewer bananas.
Bats: Secrets of the flying mammal
Bats get a bad rap for their links to the novel coronavirus and other diseases, but from pollinating plants to eating mosquitoes, these fascinating creatures of the night are an essential part of ecosystems.
From Australia's bush to Mexico's Pacific coast — hanging in trees, perched high up on mountains, hidden in caves, rock crevices, and rooftops—bats are the most widely distributed mammal on Earth, inhabiting every continent except Antarctica. Making up about 20% of all mammals, these nocturnal creatures are the second most common mammal after rodents, and the only one capable of sustained flight.
Image: Imago/Bluegreen Pictures
Leaf-dwelling, fig-eating, marshmallow puffs
Safely snuggled in the crease of a heliconia plant, these Honduran white bats have carefully cut the vein of this leaf to make it fall into a tent shape. One of only five types of white bats out of 1,400 species and only 4-5cm long, they're sometimes called the "marshmallow puff" of the bat family. As if that isn't cute enough, these tiny bats are frugivorous, surviving almost entirely on figs.
Although they've long been considered sinister creatures in many parts of the world, only three species of bat actually drink blood. They use their sharp teeth to shear away hair on the skin of their prey before making a small incision to lap up blood. Sleeping cattle and horses are their usual victims, but they have been known to feed on people, and can cause nasty infections and disease.
There's a very good reason for bats' beady eyes and comically large ears: echolation. Most bats have very poor eyesight and rely on sonar to find food in the dark. They generate extremely high-pitched sounds in their throat and project them forward. The bats' huge ears detect echoes from those sounds bouncing off the surroundings, enabling them to map their surroundings with great precision.
Image: picture-alliance/Mary Evans Picture Library/J. Daniel
Without bats, we wouldn't have avocados, mangos or bananas
Bats have incredible ecological importance, not least because of their role in pollination. More than 500 plant species depend on bats to pollinate their flowers, including banana, avocado, mango and agave plants. Some bats, like the tube-lipped nectar bat of Eduador, the Mexican banana bat and the long-nosed bat (pictured), are equipped with extraordinarily long tongues for this exact reason.
Image: picture-alliance/All Canada Photos
Perfect disease hosts
Bats are natural hosts for several viruses, such as SARS, MERS, SARS-CoV-2 and possibly Ebola, as well as Marburg, Nipah and Hendra. Scientists think their unique immune systems allow them to carry pathogens lethal to other species — a high body temperature and high levels of interferon (a substance that activates the body's antiviral state) are two characteristics thought to keep bats healthy.
Image: picture-lliance/Zuma
Invincible, just about
Although bats only have one pup a year, most of them outlive many other mammals. Some species' lifespans are 30 years, while the oldest bat on record lived to 41. They also don't age. Well, not really. Some scientific studies think the reason for their longevity is due to their unique ability to prevent and repair age-induced cellular damage, protecting them against cancer.
While most bat species feed on insects or fruit and pollen, there are also three kinds of blood-sucking vampire bats that are all indigenous to the Americas. On very rare occasions, these bats have been found with traces of human blood, though they almost exclusively feed on birds.
Yet in contrast to their sinister image, a team of German researchers has shown that these blood-suckers are also very community-minded. "They exhibit very complex social behavior," says biologist Simon Ripperger.
"They groom each other's hair," he added. "And they share their food. If a bat comes back hungry from the hunt, other bats in the roost will sometimes regurgitate the blood they've consumed and share it."
Such awareness includes social distancing in times of ill-health. When a bat is feeling unwell, it performs what Ripperberger calls "passive social distancing" whereby it becomes lethargic and is less likely to call out to its mates for social interaction — not unlike people staying at home instead of mingling with others during the current pandemic.
Animals practice social distancing too
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Don't blame bats
While vampire bats probably get more attention than their relatively small numbers deserve, many more bat species do host viruses and spread them through the animal kingdom — and increasingly to humans. Ebola, SARS, MERS (Middle East Respiratory Syndrome) and COVID-19 are believed to have originated with bats.
In part due to their high body temperatures, bats have high immunity and can tolerate infectious diseases. In their feverish state, they can host and pass on viruses that then mutate as they spread to other animals.
The role of bats in the spread of infectious disease is not surprising given that they are both the second most populous mammal after rodents, and are also highly mobile. The only mammal that can sustain flight, bats cover distances of up to 2,000 kilometers on their migratory journeys.
But while bats are being blamed for pandemics, it is in fact humans who have made themselves more vulnerable to zoonotic diseases, says the #DontBlameBats campaign.
Recent studies have shown that a sharp reduction in biodiversity, especially through deforestation, has reduced the buffer between humans and wildlife that spread pathogens originating in bats.
In some countries there's a push to cull bats because of their association with zoonotic diseases. But bats in fact will be key to re-establishing the biodiversity that will limit the spread of viruses to humans. Bats also devour huge masses of disease-spreading insects, including mosquitoes. Some bats eat more than 1,000 insects per hour.
They plant forests too
Fruit-eating bats are vital in dispersing the seeds needed to regenerate deforested areas globally. Helping to reforest tropical areas of Southeast Asia, busy bats have also been aiding in the regrowth of African woodland at a rate of around 800 hectares annually.
Meanwhile, bat species in Madagascar that feast on insect plagues that threaten rice crops are also aiding in the regeneration of deforested lands.
Research by University of Cambridge zoologist Ricardo Rocha shows how rice farmers in Madagascar were cutting down more forest to compensate for crop losses to pests. But with bats (36 species are endemic to the island) helping to save crops by feasting on plagues of insects, Rocha believes there will be less incentive to fell more trees to make way for farming.
The incredible journeys of migratory animals
From the Arctic to the Serengeti, whales, butterflies and other animals on the move make some extraordinary journeys. They mainly travel for food or sex, but some even set off in search of exfoliating skin treatments.
Image: picture-alliance/blickwinkel/McPHOTO/E. u. H. Pum
Pole to pole
It isn't unusual for animals to migrate to avoid harsh winters, but the sun-seeking Arctic tern takes this strategy to extremes. The small seabird flies between the Arctic and Antarctic to take in two summers each year and more daylight hours than any other animal. Making a round trip of 35,000 kilometers (21,748 miles), the tern breaks all records for migratory distances traveled.
Image: picture-alliance/blickwinkel/McPHOTO/E. u. H. Pum
Uphill struggle
If the tern takes prize for distance, the salmon surely deserves special commendation for effort. Hatching in rivers, they swim downstream to spend most of their lives at sea. But the hard work comes as they battle against the current and leap up waterfalls to make it home. If this wasn't struggle enough, hungry bears, eagles and people lie in wait for the exhausted fish as they near their goal.
Image: Imago/ZUMA Press/J. Mather
Midnight wanderers
By day, straw colored fruit bats hang from Africa's city trees like assemblages of broken umbrellas. But at twilight, they take gracefully to the air, traveling up to 180 kilometers before dawn and dispersing seeds and pollen as they feed. They span even greater distances by season, and in colossal numbers. Each fall, around 10 million of these "megabats" arrive in Zambia's Kasanka National Park.
Image: imageBROKER/picture-alliance
Spa break
Many whales hunt in polar regions but can travel 18,000 kilometers each year to enjoy warmer waters. Scientists had assumed they prefer to give birth in the tropics. But new research suggests they might be migrating for the sake of their skin. Whales need to molt, and in icy waters where their blood supply is drawn away from the skin, dead cells build up and put them at risk of infection.
It's hard to imagine a creature as tiny and fragile as a butterfly undertaking epic migratory journeys. And yet, surfing air currents, the monarch butterfly can travel up to 3,000 kilometers. In summer, they're at home in northern regions of the US, but when temperatures fall, they head south to California or Mexico to overwinter. Roosting together in large numbers helps them keep warm all year.
Image: M. Watson/picture-alliance/Mary Evans Picture Library
Third eye
Leatherback turtles travel up to 10,000 kilometers, from Canada to the Caribbean and Alaska to Indonesia. No one knows how they find their way from feeding grounds rich in their favorite foods like jellyfish to the beaches where they breed. But scientists believe a spot on top of the animal's head may allow light to reach its pineal gland, triggering its journey at the right moment of the year.
Image: Imago/Nature Picture Library
Following the herd
The mass movement of wildebeest across the African plains is perhaps the planet's greatest migration spectacle. With no real beginning or end, their circular route takes 1.5 million wildebeest, and a good number of zebras, gazelles and other grazers, through the Serengeti-Mara — crossing crocodile-infested rivers and dodging lions and packs of painted wolves —- in search of fresh food and water.
Image: S. Meyers/picture-alliance/blickwinkel
Slow food
Famous for their parental devotion, emperor penguins lay their eggs a good 100 kilometers from the Antarctic ocean where they feed. Mother and father must take turns to travel across the ice, fill up on fish, and make the long shuffle back to regurgitate it for their young. Their partner, meanwhile, goes hungry for weeks to shield the chick from cold that would otherwise kill it in minutes.