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7 Clever Hunting Tricks Used in the Animal Kingdom

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The animal world is full of predators with some impressive tricks up their sleeves.

1. Sun-tracking sharks

Great white sharks are the largest predatory fish in the world, and perhaps the most famous of sharks, thanks to their starring role in the Jaws franchise. But new research suggests these creatures are also quite clever. Scientists from Flinders University in Australia now say white sharks can use the sun’s positioning to their advantage when hunting. On sunny mornings, the sharks strike from the east with the rising sun directly behind them. In the afternoons, they switch directions to approach from the west. “This would suggest that the sharks are capable of tracking the sun, which is quite an impressive feat,” says Dr. Charlie Huveneers, an ecologist who led the research. By putting the sun behind them, the sharks are avoiding glare and making their unlucky prey easier to see. 

2. Bait-fishing green herons

This beautiful bird knows the best way to catch a fish is with a little bait. They’re sometimes observed dropping bits of bait—bread, for example—into the water to lure curious victims to the surface before striking. For other herons, little fish become the bait itself, used to trick bigger fish looking for a meal. Watching a heron fish with such precision and ingenuity is a creepy reminder that birds are actually really smart.

Not to be outdone by its green cousin, the black heron has another smart tactic for finding dinner: it shapes its wings into an "umbrella" that creates shade. This allows it to see down into the water by reducing the sun’s glare, but serves the dual purpose of attracting fish, which are drawn to dark areas of vegetation. You can see this ingenious trap at work here.

3. Color-changing crab spiders

Call them the chameleons of the arachnid world. The female whitebanded crab spider can change its own color from white to yellow and back again to avoid being detected while it waits patiently on flower petals before ambushing prey. Males, sadly, aren't blessed with this talent.

4. Bubble-blowing humpback whales

These giant creatures work together to corral large schools of krill or herring into one place for a massive meal. The whales swim in an upward spiral below the fish and release columns of air bubbles, which the fish won’t swim through, essentially creating a bubble net around the prey. Researchers say this hunting skill is passed on from whale to whale.

5. Sneaky crocodiles

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Mugger crocodiles in India and some American alligators have been observed lying completely still just beneath the surface of the water for long periods of time, their snouts deliberately covered by sticks. It seems these reptiles have learned that, during heron mating season, the birds need sticks to build their nests. By hiding beneath something that’s in high demand, the crocodiles and alligators nearly guarantee themselves a meal if they can wait long enough. “If the crocodylians really are using the sticks as bait to attract their bird prey,” writes Darren Naish at Scientific American, “this is tool use, since the sticks are objects that are being employed for a specific function.”

6. The fish that plays dead

Possums aren’t the only animals that play dead. In East Africa, a species of cichlid fish uses this skill to catch smaller fish for dinner. In shallow waters, the fish sinks to the ground as if dead. Some fish spend up to 15 minutes in this position, waiting for someone to take the bait. Smaller fish, convinced by the act, nibble on the corpse of the cichlid. If they come close enough, the faking fish snaps to life and nabs a meal. But this hunting method comes with a cost: Some cichlid fish sustain lifelong injuries to their fins from essentially using their own bodies as bait.

7. Mimicking jungle cats

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Mimicry is a well-utilized and impressive skill in the animal world. One good example is the morgay, or tree ocelot, in the Amazonian forests of the Reserva Florestal Adolpho Ducke in Brazil. This jungle cat mimics the call of baby pied tamarin monkeys to attract curious adult monkeys. "Cats are known for their physical agility, but this vocal manipulation of prey species indicates a psychological cunning which merits further study," says Wildlife Conservation Society researcher Fabio Rohe.

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Animal Welfare Groups Are Building a Database of Every Cat in Washington, D.C.
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There are a lot of cats in Washington, D.C. They live in parks, backyards, side streets, and people's homes. Exactly how many there are is the question a new conservation project wants to answer. DC Cat Count, a collaboration between Humane Rescue Alliance, the Humane Society, PetSmart Charities, and the Smithsonian Conservation Biology Institute, aims to tally every cat in the city—even house pets, The New York Times reports.

Cities tend to support thriving feral cat populations, and that's a problem for animal conservationists. If a feline is born and grows up without human contact, it will never be a suitable house cat. The only options animal control officials have are to euthanize strays or trap and sterilize them, and release them back where they were found. If neither action is taken, it's the smaller animals that belong in the wild who suffer. Cats are invasive predators, and each year they kill billions of birds in the U.S. alone.

Before animal welfare experts and wildlife scientists can tackle this problem, they need to understand how big it is. Over the next three years, DC Cat Count will use various methods to track D.C.'s cats and build a feline database for the city. Sixty outdoor camera traps will capture images of passing cats, relying on infrared technology to sense them most of the time.

Citizens are being asked to help as well. An app is currently being developed that will allow users to snap photos of any cats they see, including their own pets. The team also plans to study the different ways these cats interact with their environments, like how much time pets spend indoors versus outdoors, for example. The initiative has a $1.5 million budget to spend on collecting data.

By the end of the project, the team hopes to have the tools both conservationists and animal welfare groups need to better control the local cat population.

Lisa LaFontaine, president and CEO of the Humane Rescue Alliance, said in a statement, “The reality is that those in the fields of welfare, ecology, conservation, and sheltering have a common long-term goal of fewer free-roaming cats on the landscape. This joint effort will provide scientific management programs to help achieve that goal, locally and nationally."

[h/t The New York Times]

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How Does Catnip Work?
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If you have a cat, you probably keep a supply of catnip at home. Many cats are irresistibly drawn to the herb, and respond excitedly to its scent, rubbing against it, rolling around on the floor, and otherwise going nuts. There are few things that can get felines quite as riled up as a whiff of catnip—not even the most delicious treats. But why does catnip, as opposed to any other plant, have such a profound effect on our feline friends?

Catnip, or Nepeta cataria, is a member of the mint family. It contains a compound called nepetalactone, which is what causes the characteristic catnip reaction. Contrary to what you might expect, the reaction isn’t pheromone related—even though pheromones are the smelly chemicals we usually associate with a change in behavior. While pheromones bind to a set of specialized receptors in what’s known as a vomeronasal organ, located in the roof of a cat's mouth (which is why they sometimes open their mouths to detect pheromones), nepetalactone binds to olfactory receptors at the olfactory epithelium, or the tissue that lines the mucus membranes inside a cat’s nose and is linked to smell.

Scientists know the basics of the chemical structure of nepetalactone, but how it causes excitement in cats is less clear. “We don’t know the full mechanisms of how the binding of these compounds to the receptors in the nose ultimately changes their behavior,” as Bruce Kornreich, associate director of the Cornell Feline Health Center, tells Mental Floss. Sadly, sticking a bunch of cats in an MRI machine with catnip and analyzing their brain activity isn’t really feasible, either from a practical or a financial standpoint, so it’s hard to determine which parts of a cat’s brain are reacting to the chemical as they frolic and play.

Though it may look like they’re getting high, catnip doesn’t appear to be harmful or addictive to cats. The euphoric period only lasts for a short time before cats become temporarily immune to its charms, meaning that it’s hard for them to overdo it.

“Cats do seem to limit themselves," Michael Topper, president of the American Veterinary Medical Association, tells Mental Floss. "Their stimulation lasts for about 10 minutes, then it sort of goes away.” While you may not want to turn your house into a greenhouse for catnip and let your feline friend run loose, it’s a useful way to keep indoor cats—whose environment isn’t always the most thrilling—stimulated and happy. (If you need proof of just how much cats love this herb, we suggest checking out Cats on Catnip, a new book of photography from professional cat photographer Andrew Martilla featuring dozens of images of cats playing around with catnip.)

That said, not all cats respond to catnip. According to Topper, an estimated 70 percent of cats react to catnip, and it appears to have a genetic basis. Topper compares it to the genetic variation that causes some individuals to smell asparagus pee while others don’t. Even if a cat will eventually love the smell of catnip, it doesn’t come out of the womb yearning for a sniff. Young kittens don’t show any behavioral response to it, and may not develop one until several months after birth [PDF].

But some researchers contend that more cats may respond to catnip than we actually realize. In one 2017 study, a group of researchers in Mexico examined how cats might subtly respond to catnip in ways that aren’t always as obvious as rolling around on the floor with their tongue hanging out. It found that 80 percent of cats responded to catnip in a passive way, showing decreased motor activity and sitting in the “sphinx” position, an indicator of a relaxed state.

There are also other plants that have similar effects on cats, some of which may appeal to a wider variety of felines than regular old catnip. In a 2017 study in the journal BMC Veterinary Research, researchers tested feline responses to not just catnip, but several other plants containing compounds similar in structure to nepetalactone, like valerian root, Tatarian honeysuckle, and silver vine. They found that 94 percent of cats responded to at least one of the plants, if not more than one. The majority of the cats that didn’t respond to catnip itself did respond to silver vine, suggesting that plant might be a potential alternative for cats that seem immune to catnip’s charms.

Despite the name, domestic cats aren’t the only species that love catnip. Many other feline species enjoy it, too, including lions and jaguars, though tigers are largely indifferent to it. The scent of the plant also attracts butterflies. (However, no matter what you’ve heard, humans can’t get high off it. When made into a tea, though, it reportedly has mild sedative effects.)

The reason Nepeta cataria releases nepetalactone doesn’t necessarily have to do with giving your cat a buzz. The fact that it gives cats that little charge of euphoria may be purely coincidental. The chemical is an insect repellant that the plant emits as a defense mechanism against pests like aphids. According to the American Chemical Society, nepetalactone attracts wasps and other insect predators that eat aphids, calling in protective reinforcements when the plant is in aphid-related distress. That it brings all the cats to the yard is just a side effect.

Because of this, catnip may have even more uses in the future beyond sending cats into a delighted frenzy. Rutgers University has spent more than a decade breeding a more potent version of catnip, called CR9, which produces more nepetalactone. It’s not just a matter of selling better cat toys; since catnip releases the compound to ward off insects, it’s also a great mosquito repellant, one that scientists hope can one day be adapted for human use. In that case, you might be as excited about catnip as your cat is.

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