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Andy Turko, University of Guelph
Andy Turko, University of Guelph

To Cool Off, This Fish Gets Out of the Water

Andy Turko, University of Guelph
Andy Turko, University of Guelph

If you can’t stand the heat, get out of the water. That’s one fish’s strategy, anyway. New research shows that the mangrove rivulus fish (Kryptolebias marmoratus) flings itself onto land when the water gets too hot.

Plenty of fish split their time between surf and turf. Amphibious fish like K. marmoratus and the mudskipper can breathe and scoot around in the water and on land, which gives them an advantage when conditions in either place become uncomfortable or dangerous. 

But even among its weird amphibious brethren, the mangrove rivulus fish is unique. The little fish, which can be found in waters from Florida to Brazil, holds the record for the longest time spent on land. Researchers in South America found K. marmoratus living on land for up to 66 days at a time in crab burrows, beer cans, and even hollow logs. 

“We kicked over a log and the fish just came tumbling out,” one researcher memorably told Reuters

Getting out of the water can be tricky with no arms or legs, but K. marmoratus has it down to a science. The fish flings itself upward like an acrobat and flips, end over end, eventually landing on its belly. From there, it wriggles into a comfortable spot.

Why do they do this? For the same reason we jump into a swimming pool: to cool off. Researchers at the University of Guelph discovered that the fish leave the water when it gets too warm. In a paper published this week in Biology Letters, the scientists reported that the body temperature of an overheated fish drops within a few seconds of the fish leaving the water. It’s called evaporative cooling: as a fish’s wet skin dries, its body temperature drops.

This self-propelled air conditioning is an impressive and important adaptation for the fish, which live in waters that regularly reach 100.4°F.

“If the fish are prevented from jumping out of the water, they would die,” lead author Patricia Wright said this week in a press release.

Wright and her colleagues also found that, given a few days to acclimate, K. marmoratus quickly adapts to warmer water. This will serve the fish well as climate change dials up the heat in waters worldwide.

The ability to adapt is vital in an age of rapidly changing environments. K. marmoratus’s methods may be unorthodox, but they work. In time, we may just find that the weird will inherit the Earth.

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There May Be an Ancient Reason Why Your Dog Eats Poop
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Dogs aren't known for their picky taste in food, but some pups go beyond the normal trash hunting and start rooting around in poop, whether it be their own or a friend's. Just why dogs exhibit this behavior is a scientific mystery. Only some dogs do it, and researchers aren't quite sure where the impulse comes from. But if your dog is a poop eater, it's nearly impossible to steer them away from their favorite feces.

A new study in the journal Veterinary Medicine and Science, spotted by The Washington Post, presents a new theory for what scientists call "canine conspecific coprophagy," or dogs eating dog poop.

In online surveys about domestic dogs' poop-eating habits completed by thousands of pet owners, the researchers found no link between eating poop and a dog's sex, house training, compulsive behavior, or the style of mothering they received as puppies. However, they did find one common link between the poop eaters. Most tended to eat only poop that was less than two days old. According to their data, 85 percent of poop-eaters only go for the fresh stuff.

That timeline is important because it tracks with the lifespan of parasites. And this led the researchers to the following hypothesis: that eating poop is a holdover behavior from domestic dogs' ancestors, who may have had a decent reason to tuck into their friends' poop.

Since their poop has a high chance of containing intestinal parasites, wolves poop far from their dens. But if a sick wolf doesn't quite make it out of the den in time, they might do their business too close to home. A healthier wolf might eat this poop, but the parasite eggs wouldn't have hatched within the first day or two of the feces being dropped. Thus, the healthy wolf would carry the risk of infection away from the den, depositing the eggs they had consumed away in their own, subsequent bowel movements at an appropriate distance before the eggs had the chance to hatch into larvae and transmit the parasite to the pack.

Domestic dogs may just be enacting this behavior instinctively—only for them, there isn't as much danger of them picking up a parasite at home. However, the theory isn't foolproof. The surveys also found that so-called "greedy eaters" were more likely to eat feces than dogs who aren't quite so intense about food. So yes, it could still be about a poop-loving palate.

But really, it's much more pleasant to think about the behavior as a parasite-protection measure than our best pals foraging for a delicious fecal snack. 

[h/t The Washington Post]

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What Makes a Cat's Tail Puff Up When It's Scared?
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Cats wear their emotions on their tails, not their sleeves. They tap their fluffy rear appendages during relaxing naps, thrash them while tense, and hold them stiff and aloft when they’re feeling aggressive, among other behaviors. And in some scary situations (like, say, being surprised by a cucumber), a cat’s tail will actually expand, puffing up to nearly twice its volume as its owner hisses, arches its back, and flattens its ears. What does a super-sized tail signify, and how does it occur naturally without help from hairspray?

Cats with puffed tails are “basically trying to make themselves look as big as possible, and that’s because they detect a threat in the environment," Dr. Mikel Delgado, a certified cat behavior consultant who studied animal behavior and human-pet relationships as a PhD student at the University of California, Berkeley, tells Mental Floss. The “threat” in question can be as major as an approaching dog or as minor as an unexpected noise. Even if a cat isn't technically in any real danger, it's still biologically wired to spring to the offensive at a moment’s notice, as it's "not quite at the top of the food chain,” Delgado says. And a big tail is reflexive feline body language for “I’m big and scary, and you wouldn't want to mess with me,” she adds.

A cat’s tail puffs when muscles in its skin (where the hair base is) contract in response to hormone signals from the stress/fight or flight system, or sympathetic nervous system. Occasionally, the hairs on a cat’s back will also puff up along with the tail. That said, not all cats swell up when a startling situation strikes. “I’ve seen some cats that seem unflappable, and they never get poofed up,” Delgado says. “My cats get puffed up pretty easily.”

In addition to cats, other animals also experience piloerection, as this phenomenon is technically called. For example, “some birds puff up when they're encountering an enemy or a threat,” Delgado says. “I think it is a universal response among animals to try to get themselves out of a [potentially dangerous] situation. Really, the idea is that you don't have to fight because if you fight, you might lose an ear or you might get an injury that could be fatal. For most animals, they’re trying to figure out how to scare another animal off without actually going fisticuffs.” In other words, hiss softly, but carry a big tail.

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