Earth’s magical ecosystems might be on their way out, but they’re still full of awesome surprises — like these ten animal behaviors, each of which is so totally opposite to what you’d expect that they’re practically oxymoronic.
10. Flying squid
Often mistaken for flying fish, there are at least six known species of flying squid and possibly dozens more. But as seeing them in action is a blink-and-you’ll-miss-it kind of sight there’s not much for scientists to go on. Most reports come from sailors who find them on deck in the morning.
Marine biologist Silvia Maciá, however, got lucky. On holiday in 2001, she saw a torpedo-shaped Caribbean reef squid — alarmed by the noise of her boat — shoot out the water and arc through the air. Maciá estimated it reached a height of two meters and covered a distance of ten meters (50 times its own length). But this wasn’t just a jump. The squid “extended its fins and flared its tentacles in a radial pattern while airborne,” guiding its flight like an inside-out bird. As she and her husband later wrote in a paper with other biologists, “gliding” is too passive a term for it; “‘flight’ is more fitting because it implies something active.” One of Maciá’s co-authors even claimed to have seen squid flapping their fins as though wings. They also shoot water jets for extra propulsion, sometimes with enough force to keep up with boats. Sometimes they’re even seen flying in flocks.
We don’t know for sure why squid took to flying, but it probably saves them energy while escaping from predators.
9. Walking bats
Although mammals, bats have adapted so thoroughly to flight that their “legs” don’t allow them to walk. In most species, they’re little more than “attachment points for the surface of their wings.” Even crawling on the ground is an effort.
Of the 1,110 species of bat, only two have a true walking gait: the vampire bat and the lesser short-tailed burrowing bat. For the vampire bat, walking is vital. After landing near its sleeping prey, it has to stealthily creep over to feed on its blood. One type of vampire bat can even run, using its wings for additional thrust.
Less well known is the burrowing bat of New Zealand, whose adaptations for walking include grooves on the soles of its feet, clawed toes, and even pockets for keeping the wings in. In fact, this species is so well adapted for walking, it spends 40 percent of its time foraging on the ground. But it can still fly just as well as any other bat — unlike birds that are adapted for walking.
8. Bat-catching snakes
Since (most) bats can’t walk and snakes can’t fly, you’d think they’d have little to do with each other. But some snakes have actually taken to the air — at least in a manner of speaking.
In a cave in the Yucatan rainforest, a population of yellow-red rat snakes has established itself in ceiling cracks, dangling to catch bats in their mouths. Given the density of the bat swarms that issue nightly from the “Bat Cave”, as it’s known to locals, it’s a behavior that makes perfect sense.
And, interestingly, they’re not the only species to have filled this creepy niche. 1,000 kilometers away, across the Caribbean Sea, boas grab fruit bats from the air, likewise striking from the ceilings of caves. But even more surprisingly, they do so in packs — coordinating positions to boost their chance of a mouthful.
7. Fish-eating spiders
Although some spiders are known to eat frogs, rodents, and birds, what kind of spider eats fish?
According to a review of the existing literature, it’s not as unusual as it sounds. Species from as many as five genera, and every continent but Antarctica, are listed. In North America, semi-aquatic spiders catch small freshwater mosquito fish by anchoring their hind legs to a stone or plant and “fishing” with its front legs on the surface of the water.
After dragging a catch onto land, feeding often takes several hours. Why does it take so long? Because, on average, spiders catch fish at least twice as long as themselves.
6. Hornet-cooking bees
Stinging isn’t the only suicide attack deployed by nature’s boddhisattvas, the bees. When a hornet attacks a nest, hundreds of worker bees swarm into a ball around the intruder to roast it alive with their body heat. Surprisingly, this behavior, known as “hot defensive bee balls,” wasn’t documented until 1995 when it was studied in detail in Japan.
By rapidly vibrating their wing muscles for upwards of half an hour, bees are able to reach temperatures of 46 degrees Celsius, which is enough to kill the captive hornet. But while it’s just under bee-roasting point, it does seem to lower bees’ lifespan. It also seems to disinhibit them neurologically, making them more likely to join balls in the future than bees that were never involved.
Some bee species might also deploy non-heated balls to suffocate invaders, or else dance in waves to reflect shimmering signals that warn off would-be attackers. They have to act fast, though, whatever they do. Given time, hornets release pheromones to attract back-up.
5. Sea-faring spiders
You’d think spiders would be wary of water. But many species live close to and even in it. The so-called diving bell spider, for instance, lives underwater in a silken base filled, bubble by bubble, with air from the surface. Once established, oxygen levels remain stable thanks to diffusion from aquatic plants nearby.
More surprisingly, coastal spiders (Amaurobioides) are able to travel by sea — which explains how they reached South Africa from South America in the Miocene. They also got to Australia and New Zealand. Using their legs as sails and silk as an anchor, coastal spiders can travel the world.
First described in 2015, this behavior explains the mystery, noted by Darwin, of spiders blowing onto ships even miles away from the shore.
4. Immaculately-conceiving Komodo’s
In 2006 a strange report in the biology journal Nature described two cases where female komodo dragons — both captive at zoos in England — reproduced without mating a male. One laid 11 eggs, eight of which were developing normally, while the other laid 22, four of which hatched. Because the second dragon had actually mated two and a half years previously, researchers initially assumed she’d simply held onto the sperm, as some reptiles can. However, genetic analysis revealed that her offspring was identical to her, only male. The other dragon, meanwhile, had never mated.
Known as parthenogenesis, asexual reproduction is extremely rare. In the absence of sperm to provide the other half of her offspring’s chromosomes, the mother just doubles up her own. Only 0.1 percent of vertebrates are capable of this feat. The reason komodo dragons are among them is thought to be their isolated habitat, the islands of Indonesia — since parthenogenesis allows (at least in principle) females washed up on an island to found a new colony on their own.
Unfortunately, however, the offspring produced in this way are, being genetically less diverse, more prone to disease. They’re also exclusively male, since, unlike in humans, two of the same chromosomes in komodo dragons (namely ZZ) produces a male. So parthenogenesis isn’t really an advantage for this endangered species of monitor lizard.
3. Bird-catching fish
Sharks aside, the relationship between birds and fish is pretty much always top-down. Fish don’t pluck birds from the air.
Or do they? In 2014, a group of researchers in South Africa saw a tigerfish leap from a lake and catch a swallow in flight. It all happened so fast, they weren’t sure at first what they’d seen. As it turned out, it was the first ever confirmed sighting of a freshwater fish preying on a bird in mid-air. And it wasn’t their last. Before they left, the team saw as many as 20 such strikes every day. The anecdotal reports were correct: fish preying on birds is common in the region, it’s just not all that well studied.
It happens elsewhere too. Another bird-catching species is the silver arowana, a flying fish that preys not only on birds, but also bats and even mice in what’s left of the Amazon rainforest.
2. Land-stalking fish
Birds aren’t even safe from fish on dry land. On the River Tarn in Albi, France, there’s a small island where pigeons come to preen — and where catfish come to hunt them.
The European catfish is actually pretty formidable. Usually measuring between 1 and 1.5 meters long but with outlier specimens known to reach 3 meters, they’re the continent’s biggest freshwater fish. And, despite their relatively “primitive” state of evolution, their great adaptability keeps them at the top of their food chain.
To stalk the pigeons on land, catfish swim nearby, detecting vibrations with their upper jaw barbels (or “whiskers”).Then they flop out of the water and onto the island, grabbing any pigeon that moves before retreating into the depths. The whole thing takes less than four seconds.
1. Tree-climbing fish
Further making a mockery of the old saying “a fish out of water,” some species actually prefer it. By holding bubbles of water in their gill chambers, Asian mudskippers are able to breathe on dry land for up to two days, taking oxygen not only through their gills but also through their skin — as long as its wet. Specially adapted fins allow them to walk (or hop) along the ground and even their eyesight is better on land.
But humans have known this for a while. A more recent discovery by scientists catching up with local knowledge is that some can also climb trees. The dusky-gilled and slender mudskippers are two of the tree-climbing species. According to researchers, they use a combination of suction, friction, and slug-like secretions, as well as their fins, to make their way vertically up tree trunks.
Even more surprising, though, was their movement across water. Recordings of the dusky-gilled mudskipper in Java revealed it hopping off vertical inclines, such as mangrove roots, onto water, then from the water to another vertical incline on land. Using its body for propulsion, it reached speeds of 1.7 meters per second.