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Seals Might Eavesdrop on Scientific Equipment to get Easy Meals

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istock

A single fish, or even a school of them, swimming through the vast ocean isn’t an easy thing to keep track of, so scientists often rely on a little gadget called an acoustic tag. These tags give off ultrasonic “pings” that researchers pick up on hydrophones and other instruments and turn into digital data. By attaching them to or implanting them inside a fish, scientists can use them to monitor fish location, movement and survival rates.

Great care is always taken to make sure that these tags don’t hinder the animals that are being tracked, and fish don’t appear to be able to hear the pings. But that doesn’t mean other species can’t, and that might be a problem for both the fish and the scientists studying them.

Seals and sea lions have shown that they can hear fish tags’ pings from hundreds of feet away, but it wasn’t clear if the noises meant anything to them. Now, a new study suggests that the tags may be like little dinner bells for seals, helping them find tagged fish more easily and turning research subjects into easy prey.

Researchers from the UK, led by Amanda Stansbury, set up an experiment with 10 grey seals born on Scotland’s Isle of May. The seal pups were just three months old, didn’t associate sound with food, and had never even been in the ocean before. One by one, the seals were released into a long pool to find fish that the researchers had hidden in 20 boxes lining the sides. One box contained a tagged fish, one had an untagged fish in it, and the other 18 were empty. The pups searched around, poked their heads in the boxes and got a snack if they could find it.

After a few days—during which each seal got 20 turns in the pool—the seals all got faster at finding both types of fish. They not only reduced the time they needed to discover their prize, but also the number of boxes they had to check, even as the fish were moved from one hiding place to another. While the seals didn’t find the tagged fish much faster than the untagged ones, they did find them with fewer box checks and returned to the boxes with tagged fish twice as often as any of the other boxes. The researchers thought that the seals could have quickly learned to associate the tags’ sounds with food, but they might have also just been following their noses and not using sound that much during their searches.

To control for smell and other chemical cues, Stansbury and her team tried two variations of their original experiment. The first was a “tag only” trial where the seals explored the pool with just a fish tag, but no fish, in one box and all the others left empty. Even with no fish and no chemical cues to follow, the seals still checked the box with the tag in it for food faster than they did any of the other boxes. In the second “all fish” trial, the researchers filled all the previously empty boxes with fish that the seals couldn’t grab. With a tagged fish, an untagged fish, and 18 inaccessible fish all giving off odors in the pool, the seals again found the noisy fish faster than the silent one.

“Gray seals quickly learn that hearing pinging fish tags give away the location of a nice meal,” the researchers say, and they might rely on these sounds even more in the wild, where the scent of a live swimming fish would be harder to follow. This complicates things for scientists using acoustic fish tags. If tagged animals are more vulnerable to being eaten, that’s not only unfortunate for the fish, but could skew the data being collected and point researchers towards erroneous conclusions. There’s already some evidence that wild salmon wearing acoustic tags are easier pickings for predators and have lower survival rates than ones wearing silent tracking tags. And while noisy prey might make things easier for predators, a hunter that’s been tagged itself could alert its quarry and have a harder time finding something to eat. The researchers say that acoustic tagging is becoming more common in studies on sharks, and the tags could give them away to their seal prey (though shark researcher Michelle Jewell notes that the noisiness of seal colonies seems to leave them oblivious to the sounds of nearby tagged sharks).

Stansbury says that the results of the study show how important it is to consider all the effects, both good and bad, that an artificial sound might have in an environment. If acoustic tags alter the way predators and prey interact, that doesn’t mean that they’re no longer useful. Rather, finding this unintended consequence helps scientists fine tune their methods to save both themselves and the animals they’re studying a lot of trouble.

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Good News, Dog Parents: You Can Teach Puppies as Well as Their Canine Moms Can
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iStock

If you’ve ever adopted a puppy, you probably know how frustrating it can be to teach your new family member the basic tenets of common decency, like not to pee on the carpet or tear up a whole roll of toilet paper.

In other areas, though, pups are rather impressive learners, capable of mimicking some human behaviors. In fact, for some tasks, they learn just as effectively from watching people as they do from watching other dogs, including their own mothers, a new study in Nature revealed.

Researchers from Hungary and the UK took 48 young puppies of various breeds and studied the conditions under which they can be taught to open a puzzle box containing food. The experiment revealed that the puppies were able to learn how to open the box regardless of whether the task was first demonstrated by a person, their mother, or an unfamiliar dog. In other words, not only are puppies capable of social learning, but they're able to learn tasks from humans they don't know—in this case, the experimenter.

However, researchers were surprised to learn that the puppies were more likely to learn how to open the box by watching an unfamiliar dog than by watching their own mothers. That may be because puppies spend more time looking at—and thus, learning from—an unfamiliar dog that intrigues them. This differs from other species such as kittens, which “learn to press a lever for food more rapidly from their mother than from an unfamiliar adult,” the study notes.

In addition, the puppies were able to perform the task again after a one-hour break, indicating that they had retained some memory of the learning experience.

The ability of dogs to learn from humans has been recorded in previous research. A 2015 study revealed that dogs learn better by demonstration (or the “do as I do” method) than training techniques that involve a system of punishments and rewards. The "do as I do" approach probably isn't the most practical method of teaching your pup to do its business outside, but if you already have an adult dog at home, your new puppy can follow the older dog's lead and learn by example.

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Michael Hutchinson
Spiders Can Fly Through the Air Using the Earth's Electric Field
A spider exhibiting ballooning behavior.
A spider exhibiting ballooning behavior.
Michael Hutchinson

Every so often, otherwise Earth-bound spiders take to the air. Ballooning spiders can travel hundreds of miles through the air (and, horrifyingly, rain down on unsuspecting towns). The common explanation for this phenomenon is that the spiders surf the wind on strands of silk, but there may be other forces at work, according to a new study spotted by The Atlantic.

In the research, published in Current Biology, University of Bristol scientists argue that Earth's atmospheric electricity allows spiders to become airborne even on windless days. To test their hypothesis, the researchers exposed spiders in the lab to electric fields similar to those naturally found in the atmosphere.

When the electric field was turned on, the spiders began to exhibit behavior associated with ballooning—they "tiptoed" on the ends of their legs, raised their abdomens, and released silk. Spiders only exhibit this behavior when ballooning. And when they did become airborne, the spiders’ altitude could be controlled by turning the electric field on and off. When the electric field was on, they rose through the air, but when it was off, they drifted downward.

This provides a potential explanation for why spiders take to the skies on certain days but not others, and how they can fly in calm, windless weather— something scientists have puzzled over since the early 19th century. (Even Darwin was flummoxed, calling it "inexplicable," The Atlantic notes.) However, the researchers note that these electric fields might not be totally necessary for ballooning—wind alone might work perfectly fine on some days, too. But understanding more about when and how spiders become airborne could help us predict when there will be large masses of arachnids flying through the skies (and hide).

[h/t The Atlantic]

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