'Hide or get eaten,' urine chemicals tell mud crabs

January 8, 2018, Georgia Institute of Technology

Psssst, mud crabs, time to hide because blue crabs are coming to eat you! That's the warning the prey get from the predators' urine when it spikes with high concentrations of two chemicals, which researchers have identified in a new study.

Beyond decoding crab-eat-crab alarm triggers, pinpointing these compounds for the first time opens new doors to understanding how chemicals invisibly regulate marine wildlife. Insights from the study by researchers at the Georgia Institute of Technology could someday contribute to better management of crab and oyster fisheries, and help specify which pollutants upset them.

In coastal marshes, these urinary alarm chemicals, trigonelline and homarine, help to regulate the ecological balance of who eats how many of whom—and not just crabs.

Blue crabs, which are about hand-sized and are tough and strong, eat the mud crabs, which are about the size of a silver dollar, and thin-shelled. Blue crabs also eat a few oysters, but mud crabs eat a lot more oysters than they do. When blue crabs are going after mud crabs, the mud crabs hide and stay still, so far fewer oysters get eaten than usual.

Humans are part of the food chain, too, eating oysters as well as blue crabs that boil up a bright orange. The blue refers to the color of markings on their appendages before they're cooked. Thus, the blue crab urinary chemicals influence seafood availability for people, as well.

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Fish found to communicate with one another using urine

February 2, 2017 by Bob Yirka

 (Phys.org)—A trio of researchers with the University of Bern in Switzerland has found that at least one species of fish communicates with others of its kind using chemicals in its urine. In their paper published in the journal Behavioral Ecology and Sociobiology, the team outlines experiments they conducted with a cichlid fish and what they discovered. 

Prior research has shown that some species of animals use urine as a means to communicate with one another. In this new effort, the researchers sought to learn if fish might also do so, because it seemed logical—they are not able to speak and could easily transmit chemicals through water via urine.

To find out, they inserted a partition in the middle of a fish tank that prevented fish on either side from interacting physically with one another. In some scenarios, the barrier had tiny holes to allow water to pass between the sides, while in others it did not. Also, some barriers were opaque and others were transparent. In addition, the researchers injected the fish with a blue dye that allowed them to see and measure urine being expelled by the fish once in the tank.

The researchers measured how much urine was expelled under a variety of situations—in which only one fish was in the tank; in which there were two but they could not see each other; in which there were two and they could see each other but were or were not able to communicate via urine through the barrier—the team also used a variety of fish sizes and noted fish behavior throughout each test.

The researchers looked at their results and noted that when two fish saw one another in the tank, they raised their fins and approached each other in an aggressive manner, and both emitted more urine than when they were not able to see another fish. Also, they found that only when the urine was allowed to move through the barrier was there a noticeable change in behavior of the fish—in such cases, the smaller fish generally reduced its aggressiveness, yielding to the larger one. Interestingly, the researchers also noted that when the urine was not able to pass through the barrier and the fish were able to see one another, both emitted more urine than in any other scenario, apparently aware that their message was not getting through.

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Glowworms Spit Out Urine Ingredient to Make Webs Sticky

By Laura Geggel, Senior Writer | December 15, 2016 02:35pm ET

Baby glowworms could be the interior designers of the cave world, if it weren't for their morbid machinations. These developing worms sit inside a tube of mucus on cave ceilings, sending out a curtain of sticky threads that look like sparkling beaded necklaces.

The purpose of the dazzling threads, rather than to enchant cave homes, is to trap unsuspecting insects. And now, researchers think they may have found the secret ingredient in the worms' traps: urea from their guts. 

The urea allows moisture in the humid cave to form droplets on the glowworms' secreted threads, the researchers found. These sticky, watery droplets trap insects drawn toward the blue-green light produced by the glowworms, the researchers said.

Baby glowworms could be the interior designers of the cave world, if it weren't for their morbid machinations. These developing worms sit inside a tube of mucus on cave ceilings, sending out a curtain of sticky threads that look like sparkling beaded necklaces.

The purpose of the dazzling threads, rather than to enchant cave homes, is to trap unsuspecting insects. And now, researchers think they may have found the secret ingredient in the worms' traps: urea from their guts. 

The urea allows moisture in the humid cave to form droplets on the glowworms' secreted threads, the researchers found. These sticky, watery droplets trap insects drawn toward the blue-green light produced by the glowworms, the researchers said. 

It's about time scientists solved this sticky mystery, said study co-lead researcher Janek von Byern, a postdoctoral fellow at the Institute of Zoology at the University of Vienna and the Ludwig Boltzmann Institute for Experimental and Clinical Traumatology in Austria.

Continued

Did Peeing Swimmers Kill 500 Fish?

(NEWSER) – It's a pisser. Swimmers who pee in a lake could be responsible for the death of 500 fish. Experts believe a significant amount of urine in popular Eichbaum Lake in northern Germany is linked to an algae bloom that poisoned the fish. "Swimmers who urinate in the lake are introducing a lot of phosphate," a spokesman for the Hamburger Angling Association told Bild newspaper. "We're calculating half a liter of urine per swimmer per day." Phosphate contributes to the build-up of blue-green algae. Swimmers are currently barred from the lake because of the algae bloom.

But swimming enthusiasts claim anglers are promoting the leaky urine-algae link because they want the swimmers out of the water. Some environmental observers think the problem may be caused in part by ice skaters who wake up the fish during hibernation. The fish can't find enough oxygen then under the ice, and their bodies are only now being found, reports the German Local. Hamburg's Urban Development and Environmental Authority is calling in the local university to test the pee-death theory.

http://www.newser.com/story/145940/did-peeing-swimmers-kill-500-fish.html?utm_source=part&utm_medium=huffpo&utm_campaign=strangestuff_rss

Sexy monkeys wash with own urine

By Matt Walker
Editor, Earth News

Capuchin monkeys have what at first glance appears to be an odd habit: they urinate onto their hands then rub their urine over their bodies into their fur.

Now scientists think they know why the monkeys "urine wash" in this way.

A new study shows that the brains of female tufted capuchins become more active when they smell the urine of sexually mature adult males.

That suggests males wash with their urine to signal their availability and attractiveness to females.

We reasoned that urine washing by males might provide chemical information to the females
Primatologist Dr Kimberley Phillips

Details of the finding are published in the American Journal of Primatology.

A number of New World monkey species, including mantled howler monkeys, squirrel monkeys and the few species of capuchins, regularly "urine wash", urinating into the palm of the hand, then vigorously rubbing the urine into the feet and hindquarters.

Several hypotheses have been put forward as to why they do it, including that it may somehow help maintain body temperature or allow other monkeys to better identify an individual by smell.

Most studies into the behaviour have been inconclusive.

"But one study reported that when being solicited by a female, adult males increased their rate of urine-washing," said Dr Kimberley Phillips, a primatologist at Trinity University in San Antonio, Texas, US.

"Since female capuchins [when they are most fertile] actively solicit males, we reasoned that urine washing by males might provide chemical information to the females about their sexual or social status," she told BBC News.

To investigate, Dr Phillips and her colleagues scanned the female monkeys' brains while the animals sniffed adult male and juvenile male urine.

These magnetic resonance imaging (MRI) scans revealed that female tufted monkeys' brains became significantly more active when they sniffed the scent of urine produced by adult males compared to that from juveniles.

Since adult males are sexually mature, they excrete higher concentrations of the male sex hormone testosterone in their urine.

The concentration of this testosterone is also linked to their social status; higher status males tend to produce more.

"Female capuchin monkey brains react differently to the urine of adult males than to urine of juvenile males," said Dr Phillips.

"We suggest that this is used as a form of communication to convey social and or sexual status."

She added that it was surprising that capuchin monkeys appeared to respond to these cues, because the species is not known for using communication based on smell.

Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/earth/hi/earth_news/newsid_9404000/9404757.stm

Published: 2011/02/24 08:47:37 GMT