Surfing The Wierd

Tuesday, January 29, 2008

sites for animals that change gender

  1. Uncovering Sex-change Secrets Of Black Sea Bassthe mechanismsms that determine sex in animals vary widely, involving actions of ... Of Sex (Apr. 5, 2002) — The genetic intricacies of salmon sexes and the ...
  2. Uncovering Sex-change Secrets Of Black Sea Bass

    ScienceDaily (Apr. 12, 2006) — In a former cowshed on the edge of the University of New Hampshire campus, David Berlinsky, assistant professor of zoology, peers into a big blue plastic tub. Inside, black sea bass circle slowly in the dim light. The converted barn is now an aquaculture research facility for the College of Life Sciences and Agriculture, and home to Berlinsky’s latest research.

    Black sea bass feature prominently on many menus, but wild populations of the fish are in decline and their availability is limited. Because of the high demand, they’re a good candidate for aquaculture on the east coast. Except, that is, for one problem: they have a tendency to change sex unpredictably in captivity.

    “In the wild, black sea bass are born as females and turn into males at around two to five years old,” Berlinsky explains. “When you bring them into captivity, they change into males more quickly.” Some captive-born fish emerge as males even before reaching adulthood, devoting energy toward reproductive development and away from growth. Such problems make breeding and growing the fish in captivity a tricky proposition.

    “Black sea bass is a wonderful fish to culture and to eat,” says George Nardi, vice president and director of GreatBay Aquaculture, a commercial fish farm in Newington, NH. But the sex change problem must be tackled if fish farmers are to bring a high-quality fish to market. “We invest in our brood stocks, the parents of the young fish, much as a thoroughbred horse farm invests in mares and stallions,” he says. “It doesn’t do us much good if we always have to go out and get new females.”

    With funding from NH Sea Grant, Berlinsky has teamed with Nardi and GreatBay Aquaculture to study what triggers sex reversal in black sea bass – and how to prevent it. Berlinsky and his colleagues have discovered that fish are more likely to become males if raised at constant temperatures. But temperature is hardly the only factor involved. Sex ratios and density also come into play. Berlinsky’s team found that females were more likely to change sex when no males were present in the tank. Additionally, the fish were more likely to turn into males when kept in crowded tanks.

    Berlinsky is continuing his experiments to clarify the role that water temperature plays and to further understand what factors determine the initial sex of captive-born fish. He’s also collaborating with Canadian researchers to study the underlying biochemical mechanisms that cause the fish to change sex. In female fish, estrogen plays the major role, he said. In males, a steroid hormone called 11-ketotestosterone is involved. The scientists are now studying those hormones as well as the enzymes that control them.

    By turning off estrogen production, Berlinsky says, he can turn a female fish into a male within a week. Giving 11-ketotestosterone to a female converts it into a male. “We’re studying the ways to control the enzymes that control sex reversal,” he explains. “We’re coming at the problem both behaviorally and biochemically.”

    Though he still has details to sort out, Berlinsky believes he has already made important steps. “We have already made progress, determining optimal sex ratios and delaying sex reversal by controlling density,” he notes. “We’ve already made strides toward making black sea bass aquaculture possible.”

    Adapted from materials provided by University of New Hampshire.

  3. Our results indicate that the relative size. of sex change is invariant across all animal ... Figure 2 Animals change sex at the same relative body size. ... - 147k - View as html
  4. ... concentrate on animals it should also be remembered that sex is also important ... It was widely believed that cocks that changed sex and laid eggs were ... - 32k - Cached
  5. Animals that did not copulate did not have distinct sexes in his view. ... change in animals there was no change of chromosomes when the animal changed sex. ... - 83k - Cached
  6. ... for animals that can procreate asexually and animals which change sexes in the ... creatures and creatures that change sexes in the absence of the opposite sex. ... - 167k - Cached

  7. Animals that are labeled male are individuals that changed sex— i.e., those that ... were predictive of which animal changed sex, we ran a logistical regression. ... - 81k
  8. "This suggests that there is a fundamental similarity across all animals ... to change gender when there is a serious imbalance between the sexes and it ...
  9. Species Switch Sex at Specific Size
    Male Today, Female Tomorrow
    Male Today, Female Tomorrow

    Oct. 27, 2003 — Species that automatically change sex do so when they reach nearly three-quarters of their maximum size, neatly proving a cornerstone of evolutionary theory, scientists said.

    Dozens of animal species, from types of fish and crustaceans to mollusks and worms, spontaneously change sex as a result of the pressures for survival and reproduction.

    In the case of the clownfish, a favorite of aquarium-lovers, the gender bending is taken to extremes — males can not only switch to female, but also increase in size to become the alpha-breeder in their piscatorial group.

  10. Biologists David Allsop and Stuart West of Edinburgh University in Scotland studied 77 sex-changing species, ranging from a tiny shrimp, the Thor manningi, to a 1.5-meter (5-foot) fish called a black grouper.

    They found that the creatures swapped gender when they reached 72 percent of maximum size, regardless of mating system, sex-change mechanism and other factors.

    "This suggests that there is a fundamental similarity across all animals ... in the underlying forces that select for sex change," they wrote in Thursday's issue of Nature, the British weekly science journal.

    Under evolutionary theory, an individual is at most pressure to change gender when there is a serious imbalance between the sexes and it has reached an age and size where it can do the switch successfully and contribute quickly to the gene pool.

  11. Animals that did not copulate did not have distinct sexes in his view. ... change in animals there was no change of chromosomes when the animal changed sex. ... - 128k - Cached
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  1. Why write a FAQ about African Dwarf Frogs? What is an African Dwarf Frog (ADF) ... do not change their gender or sex if you have a tank full of only one gender. ... - 89k - Cached
  2. In Depth Information on Common Aquatic Clawed Frogs. For Sale. In Depth African Clawed Frog Diet ... 4-6 months depending on size, gender and age of frog. ... - 39k - Cached
  3. African Union Monitor. 16 Days of Activism Against Gender Violence. Women and Gender ... Is it possible to study climate change effects on things you don't know even ... - 20k - CacV
  4. Vanishing frogs
    ... group of frog-like amphibians that are usually distinguished from frogs by the ... of these animals to adapt to changing conditions has resulted in the large ... - 19k - Cached
  5. Frogs help hunt down the gender benders - 06 June 1998 - New Scientist
    THE spread of sex-change chemicals in the environment could soon be tracked with a test that uses tadpoles and ... from the African clawed frog Xenopus laevis ... - 38k - Cached
  6. Natural Habitat
    African clawed frog site with lots of info. Facts, care instructions, pictures, links. ... states that since African Clawed Frogs are adapted to stagnant ... - 15k - Cached
  7. ... first time in a cold-blooded vertebrate, the South African clawed frog Xenopus. ... Gray's medical work called world-changing. Rains offer hope for bird ... - 47k - Cached
  8. *Click here for a larger view of all the pics on this page.* TANK CARE &nbsp. page created with Easy Designer ... - 23k - Cached
  9. ... symbolic expressions and musical meaning, gender, religion, and social change. ... frogs (the largest frogs in the world) in Cameroon and the African penguins ... - 82k - Cached
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Change Sexes - Sheephead Fish

Sheephead Fish Change Sexes You might find a California sheephead like this one roaming the rocky reefs and kelp forests that line the shore from the Channel Islands to Monterey. Amazingly, sheephead are all born females! It is only later in life that all of the fish will go through a change that transforms them into males.


Saturday, January 26, 2008

Aggression as Good as Sex, Dope & Rock and Roll

Aggression feels as good as sex, drugs, and rock and roll

Everyone gets a rise out of watching the 5 foot 8 receiver get jacked up by the 250 pound linebacker. Here's why 16 million viewers of Sunday Night football can't help but love watching the big hits.

The brain processes aggression as a reward, similar to the way it reacts to sex, food and drugs, according to new research.

In a series of experiments on mice, scientists discovered that mice will literally push the button willingly to introduce more aggression into their lives. Behaving just as they would for the good stuff.

"Aggression occurs among virtually all vertebrates and is necessary to get and keep important resources such as mates, territory and food,” says Craig Kennedy, professor of special education and pediatrics at Vanderbilt University. “We have found that the ‘reward pathway’ in the brain becomes engaged in response to an aggressive event and that dopamine is involved.”

In the experiments, a male and a female mouse were housed in a cage. Next door, five hungry males waited eagerly for a chance at the lady. The scientists then removed her from the cage and introduced an intruder male mouse in her place.

Things got nasty.

Later, the lone male mouse was taught how he could poke at a target and introduce an intruder into his cage, all by himself. Each day, when the target was introduced, the lone mouse couldn't help himself but pull the trigger.

When the guy was treated with a drug that suppressed his dopamine receptors, he stopped inviting trouble into his home.

"It is well known that dopamine is produced in response to rewarding stimuli such as food, sex and drugs of abuse," said Maria Couppis, who conducted the study. "What we have now found is that it also serves as positive reinforcement for aggression."

The Vanderbilt experiments are the first to demonstrate a link between behavior and the activity of dopamine receptors in response to an aggressive event.

“We learned from these experiments that an individual will intentionally seek out an aggressive encounter solely because they experience a rewarding sensation from it,” Kennedy said. “This shows for the first time that aggression, on its own, is motivating, and that the well-known positive reinforcer dopamine plays a critical role.”

COMMENTS: I wonder if Bushie-Baby gets his dopamine fix via proxy - the aggression of his wars, the violence of fighting and dying of so many thousands of people. WOW! What a rush!


Intelligent Design vs Darwinism

Intelligent Design documentary film is so good its creators will pay you to see it

6bb7c_expelled-250x250.jpg Well, not you, specifically, but if you're a gullible Christian student, get on the money train and see Expelled: No Intelligence Allowed, to earn sweet cash for your Christian school. The producers of this Intelligent Design doc are offering cash donations to Christian schools in return for ticket stubs proving attendance (or at least purchased tickets). Breaks down like this (from the website):

* 0-99 ticket stubs submitted = $5 per ticket stub * 100-299 ticket stubs submitted = $1,000 donated to your school * 300-499 ticket stubs submitted = $2,500 donated to your school * 500 ticket stubs submitted = $5,000 donated to your school

"Each school across the nation will be competing for the top honor of submitting the most ticket stubs with that school having their $5,000 donation matched for a total donation of $10,000!"

So is this movie, hosted by Ben Stein and featuring appearances from Richard Dawkins (man just can't resist a pissing match) and science hacks Jon Wells and Michael Eignor, worth being paid to see? Check the trailer after the jump.

(The trailer's You Tube site has been acting buggy all day, so if it do


Cloak of Silence

Physicists introduce a "cloak of silence"

In 2006, invisibility cloaks took the world by storm, thanks to a joint effort by mathematicians, physicists and Harry Potter.

This year, however, the physicists have another surprise: you can be invisible AND silent!


Two independent teams of scientists came up the plans for a “cloak of silence,” a device which will be able to create a pocket of silence around an object by redirecting sound waves. Some physicists used to think such a device was mathematically impossible, but the two teams, one from Duke and the other from the Hong Kong University of Science and Technology, say their equations check out. (Image courtesy of Duke.)

The technology can be used by engineers to build better concert halls or hide submarines from sonar, but it’s unlikely that the scientists will come up with a cloak you can throw over your neighbor’s noisy dog. (And if a tree fell in the forest and everyone was wearing an acoustic cloak, would it make a noise?)

A Spanish physicist has taken up the task of actually building a cylindrical acoustic cloak.

From the physicsworld article:

The considerable challenge of building an acoustic cloak has been taken up by José Sánchez-Dehesa and colleagues at the Polytechnic University of Valencia in Spain. The team has calculated that a cylindrical cloak can be made by surrounding the region to be cloaked with a matrix of cylindrical rods (to be published in New Journal of Physics). By choosing rods with the right elastic properties and by varying the radius and spacing of the rods , Sánchez-Dehesa believes that cloaking can be achieved over a wide range of acoustic frequencies. The team are now looking for an appropriate material for the rods.

Sánchez-Dehesa told that the theoretical breakthroughs in the US and Hong Kong mean that it should be possible to build a spherical cloak by surrounding a region with a matrix of spheres in a manner consistent with the recipe proposed by Cummer, Chen and Chan.

Also see:


Creating Life? Fundies Will Squall Like Panthers!

Video: How to make man-made DNA come alive

Synthetic biology has been in the news lately - i.e., building designer genomes from scratch, leading (as people like Craig Venter hope) to fully man-made, programmable life forms.

But it took nature billions of years to make inanimate chemicals "jump to life." How are WE gonna do it?

Instant Egghead to the rescue!

Written, produced and edited by John Pavlus / Camera by Steven Boling


Researchers a step closer to synthetic life

Researchers at the Venter Institute in Rockville, Md., have completed phase two of a three-part plan to create synthetic life.

Craig Venter, the scientist-entrepreneur who founded the institute and jump-started the race to map the human genome, announced the achievement Thursday.

The research team succeeded in creating a man-made copy of the genome for a bacterium, the first time that's been done. A genome is the complete set of DNA in the chromosomes of a living organism, the instruction set for how an organism works.

But while they were able to copy the genome of an existing organism, they weren't able to create a brand new one. Essentially, they managed to write the "software code" for a bacterium but they haven't yet figured out how to turn it on and make it live.

Once that's possible, it opens the door to building made-to-order organisms that could do things natural organisms don't: plants that take up large amounts of carbon from the atmosphere to slow global warming, microbes that turn grass clippings into fuel, bacteria that eat sugar and produce medicine.


Some researchers believe that's a long way off.

"These guys have not synthesized a brand new life form," says Jim Collins, a professor of biomedical engineering at Boston University. Science still has a long way to go to understanding the underlying biology of life necessary to do that, he says.

There are "multiple barriers to this," Venter acknowledges. "But we're confident that they can be overcome."

Another worry: Once this technology becomes commonplace, it can be used to create both good organisms and dangerous ones, says David Magnus, director of Stanford University's Center for Biomedical Ethics.

Venter's team has already genetically modified the bacterium to make it non-infectious.

Their report appears in today's issue of the journal Science.


Wierd Amphibians

Top 100 weirdest amphibians list launched

Movie Camera
  • 09:58 21 January 2008
  • news service
  • Catherine Brahic
Click here for a gallery of weird and wonderful amphibians They have tentacles coming out of their heads, live underground for months on end, do not need to feed for up to 10 years, and survived whatever killed the dinosaurs. The Zoological Society of London in the UK has launched the top 100 list of the world's weirdest, most wonderful and rarest amphibians "They're extraordinary survivors," says Helen Meredith of ZSL. "Ninety percent of our top 100 amphibians survived the extinction of the dinosaurs." Yet they are also in dire need of help to ensure they will continue to survive. Meredith coordinates the society’s new EDGE Amphibians initiative, a follow up of the EDGE mammals initiative, which was launched in 2007. Using the World Conservation Union's list of endangered amphibians and a complete family tree of amphibians, the group has determined which amphibians are rare and threatened with extinction, as well as genetically distinct. Skin breather Of a total 6000 amphibian species, EDGE has identified 799 rare and unique ones. It will focus its conservation efforts on the top 100, raising funds and awareness and running conservation projects. "An alarming 85% of the top 100 are receiving little or no conservation attention and will become extinct if action is not taken now," says Meredith. Her personal favourite is the Chinese giant salamander, a slimy lizard-like animal which breathes through its skin. At 1.8 metres in length, it is the world's largest amphibian, and the last remaining example of the giant amphibians that once roamed the Earth. The Chinese giant salamanders emerged a whopping 100 million years before Tyrannosaurus rex appeared. Some 200 million years later, their flesh is now a delicacy in Asia, contributing to the decline of the species. Although the reasons for the disappearance of some amphibians are clear, "a lot of them decline completely enigmatically because they are very sensitive to changes in their environment that we can barely perceive," says Meredith, who refers to amphibians as the "canary in the coalmine". "If the amphibians start to decline on a global scale we know we are inhabiting a dying planet," she adds. 'Cute' creatures Other strange creatures on the list include a cave-dwelling salamander from Europe, known as the olm, which is blind, has transparent skin, and can live for up to 10 years without feeding. What is thought to be the smallest frog in the world is also on the EDGE list –the Gardiner's Seychelles frog grows to just 11mm long. The Gardiner's frog's closest relative is the purple frog from India, which lives most of the year up to 4 metres underground and only comes to the surface during the monsoon, when it can't breathe in the waterlogged soils. Meredith, finds amphibians just as charismatic as more “cuddly” creatures like the slender loris. "If everyone had tentacles coming out of the sides of their heads we wouldn't think they were so unusual," she says. "To me, the amphibians are just as gorgeous as cute mammals and in some ways more interesting." Endangered species – Learn more about the conservation battle in our comprehensive special report.


Bull Sized Rodent Bull-Size Rodent Discovered -- Biggest Yet Click here to find out more! James Owen for National Geographic News January 16, 2008 A one-ton "fossil rat" has been discovered in South America, scientists announced today. (See pictures of the giant rodent.) The prehistoric, bull-size creature—the world's largest recorded rodent—has been identified from a well-preserved skull. The megarodent lived in lowland rain forests between two and four million years ago, perhaps using its massive teeth to fend off saber-toothed cats and giant, flightless, meat-eating birds, researchers say. The newfound species, called Josephoartigasia monesi, is reported today in a study led by Andrés Rinderknecht of the National Museum of Natural History and Anthropology in Montevideo, Uruguay. The rodent weighed about 2,200 pounds (1,000 kilograms), based on an analysis of its 21-inch-long (53-centimeter-long) skull, according to the study, published in the new issue of the journal Proceedings of the Royal Society: B. Found by an amateur paleontologist in a cliff face along Uruguay's southern coast, the skull suggests that the species was twice as heavy as any other known rodent, Rinderknecht said in an email. "The future can bring big surprises. But at present J. monesi is the largest recorded rodent," he said. A relative of rats, mice, and guinea pigs, the creature measured some ten feet (three meters) long, nose to tail. The ancient animal looked a lot like the capybara, the world's largest living rodent, also from South America. (Watch video of an anaconda hunting a capybara.) But the prehistoric mammal belonged to a rodent family with a single surviving member—the pacarana (see photo)—the study says. A rare species weighing up to 33 pounds (15 kilograms), the pacarana is confined to tropical forests in central South America. J. monesi inhabited forests around river deltas or estuaries, the study suggests. Fruit Feeder "It probably fed on aquatic plants and fruits, because its molars are small and not good for grass or other abrasive [vegetation]," Rinderknecht said.

"But a mystery is the extremely broad incisors," he added. "We are working on a biomechanical model to estimate the bite force of this giant."

The rodent's fearsome front teeth and large size may have been used to fight over females for breeding rights, assuming it was a male, he said.

The may also have helped defend against predators, including carnivorous marsupials, saber-toothed cats, and so-called terror birds, which grew up to ten feet (three meters) tall (photo of a terror-bird model), he said.

Larger mammals also have the advantage of access to low-quality food resources, such as wood, that smaller species are unable to digest, the researcher added.

"There are many advantages for a big mammal," he said. "Some of these reasons could be the explanation" for J. monesi's size.

The fossil discovery takes the title of rodent heavyweight champion away from another extinct South American species, Phoberomys pattersoni. Likened to a giant guinea pig, P. pattersoni weighed an estimated 1,500 pounds (700 kilograms). (See pictures of the prehistoric "giant guinea pig".)

The previous record holder was described in 2003 from remains found in Venezuela by paleontologist Marcelo Sánchez-Villagra from the University of Zurich, Switzerland.

Of the latest find, Sánchez-Villagra said, "This undoubtedly is the largest rodent that we know of. It's quite remarkable. But I'm not envious—I think it's great.

"I suspected there would be larger rodents out there," he said. "There are probably others that are bigger still."

The latest find is further evidence of the incredible diversity seen in South American fossil rodents, Sánchez-Villagra said.

"There were many species with no equivalent today, especially in terms of size," he added.

The likely reason for such variety is that South America's rodents evolved in isolation, the paleontologist said.

Rodent Island

"For most of the last 65 million years, since shortly after the dinosaurs became extinct, South America was an island," he said.

But around three million years ago the Panama land bridge formed, linking North and South America. New types of mammals flooded in from the north, perhaps sending bizarre species such as J. monesi scurrying to extinction.

Newcomers included predatory cats and bears that were previously absent in South America, Sánchez-Villagra said.

"Large herbivores from North America probably competed with the big rodents," he added.

Climate change likely also contributed to the demise of massive rodents, the paleontologist said.

The new discovery should provide important new clues to the growth processes that produced such massive rodents, he said.

Rinderknecht, the study author, said the team is now investigating the fossil skull to work out the animal's hearing and smelling capabilities.

"We are also looking for more remains of the rodent," he said.