Almost three-forths of the world's surface is covered in water. This water is home to over 20,000 different species of fish. The earliest fossils of fish date back over 400 million years.
There are a wide variety of fish — from the goby which is less than one half an inch long, to the whale shark which can be over 60 feet long.
Most fish breathe through gills. Gills perform the gas exchange between the water and the fish's blood. They allow the fish to breathe oxygen in the water.
Fishes are vertebrates that have a skeleton made of either bone or cartilage. About 95% of fishes have skeletons made of bone. These bony fishes have a swim bladder, a gas-filled sac, that they can inflate or deflate allowing them to float in the water even when not swimming. Fishes with a cartilage skeleton tend to be heavier than water and sink. They must swim to keep afloat. Cartilaginous (cartilage) fish include the ray and the shark.
Most fish swim using a tail fin. Muscles in the tail fin move it from side to side, forcing water backward, and propeling the fish forward. Other fins help the fish change direction and stop. Pectoral fins on their side help them swim up and down. Dorsal and anal fins on the top and bottom keep the fish upright. Pelvic fins on the underside help steer left and right.
Many fish eat plants, while others such as the shark, eat other fish.
From: http://www.kidport.com/RefLIB/Science/Animals/Fish.htm
Fish
Virginity
The obsession over female virginity traces its way back to the days where women were considered the property of men - and the heirs produced by a woman were the key reason of having her around. It was of critical importance that a man could guarantee that any child that came from the woman was "his" so that his land and wealth only went to his own offspring. This is why the woman had to be a virgin - so there was NO chance of her already having another child inside her when she married the man.
Luckily for men (I say this tongue in cheek), there was sort of a way to "prove" that a girl was a virgin. The way a man impregnates a woman is for him to put his male sex organ into her. The opening into which he puts his sex organ is protected from dust and dirt and such during her younger years by a thin membrane - a "hymen". This is sort of like your eyelid, it's a thin layer of skin that mostly closes off her opening to keep it clean. The very first time the man enters her, he breaks away this layer of skin. When it rips, it often hurts, and it also bleeds. So that blood from the ripped hymen is what a man would look for as "proof" that nobody else had entered her before he had.
Unfortunately for possessive guys, this is not a foolproof method. A hymen is just a piece of skin. It can easily break at other times too! Hymen are known to break from heavy exercise, from horseback riding, from bike riding, from many other activities. Tampons can rip them. A hymen is not a magical substance. It's just a piece of skin, and it can tear and rip. In some girls, the hymen is so thin that it wouldn't even bleed enough to be shown, even if it was there during the "first time".
There's no "proof" of virginity with a guy. Their organ is just the way it is. It can go in and out of a woman without any difference being shown.
In modern day society, virginity does not matter as a physical act. With birth control, it is very easy to have intercourse without worrying about having "heirs". And as we know, sperm are very mobile and a girl can easily get pregnant even if she is not actually entered. So NOT having been entered is no guarantee that she is not pregnant. What most people concern themselves with is the honesty of the FEELINGS between two individuals. You might have had sex in the past - but it could have been just casual, for fun. If the way you FEEL with each other is incredibly special - if that FEELING is one that you have never felt before, then that is what should be celebrated. It is that emotional contact, that feeling of oneness, that is the true sign of a special breakthrough that only you two share.
From: http://www.romanceclass.com/miscr/whatis/virginity.asp
What Is Love?
We live in a world where everything can be measured. Our scales give us our weight down to the tenth of a pound. The weather forecasters know the exact temperature. It's no wonder that we want some sort of a chart to use that says for sure "This is not love" and "this is love". Unfortunately for lovers, emotions are not an exact science.
Every single one of us is a unique human being, with unique backgrounds, unique parents, unique views of the world. This very much applies to the word "love". There is no set meaning for this word. It in fact means many different things naturally. You can love pizza. You can love Orlando Bloom. You can love your mom and dad, and love your dog. And you can love your boyfriend or girlfriend. All of these mean quite different things to you.
So one of the most important things you can learn as you grow up is where YOU draw that line. You, personally. It is fully, completely, and totally up to YOU what you choose to call "love". Others may and will probably try to influence you. But this is one of those "core personality traits" that you need to develop for yourself.
Some people fall in and out of love daily. They love every new person they meet - at least for a few hours. Some people only fall in love after dating for several months, after getting to know what a person is really like. And some people *like* everybody that is kind to them, but a real *love* is reserved for that one special person, and is only said when the next words are then going to be "and I want to marry you." So there are many different levels of how people choose to define love.
The most common way people define love for themselves is in the middle of the extremes. It involves REALLY knowing a person, inside and out. You have known them for several months. You have seen them at all times of emotion - you've seen them happy, you've seen them sad, you've seen them bored, you've seen them excited. You have been through good times together - but you've also been through bad times. You are out of the 'new love rush' that comes when relationships begin, and even in the "bright light of day" you still care for them. You SEE and ACCEPT their faults, you don't try to claim this person is perfect. But even with those faults, you accept the faults as a part of them.
Love is not a crush - love involves someone you really know fully, not someone you admire from afar. Love is not lust - love involves really wanting to care for and help someone, not just admiring their body and wanting to touch them.
If you love someone, you are content just sitting with them for the afternoon, not being "seen", not touching each other, but just spending time together. If you love someone, then you trust them fully. You readily share all your hopes, dreams and fears, and you are not "afraid" of talking about any topic with them.
From: http://www.romanceclass.com/miscr/whatis/love.asp
National Aeronautics and Space Administration (NASA)
NASA stands for National Aeronautics and Space Administration. NASA was started in 1958 as a part of the United States government. NASA is in charge of U.S. science and technology that has to do with airplanes or space.
What Does NASA Do?
NASA does a lot of different things. NASA makes satellites. The satellites help scientists learn more about Earth. NASA sends probes out into space. NASA scientists study things in the solar system, and even farther away. A new program will send humans to the moon, Mars and beyond. People at NASA work on ways to make air travel better for everyone on Earth, too. People at NASA also share the things they learn with others. This can help make life on Earth better.
Do you like science, math and learning new things? Would you like to be an adventurer? Would you like to plan future missions to other planets and outer space? People in NASA's Education Office work hard to share news about NASA's missions to learn about Earth and space with teachers. Then teachers work with students to get them ready to be engineers, scientists and astronauts. Learn more about what NASA has for students in grades K-4 on NASA's education Web pages.
Where Is NASA?
NASA Headquarters is in Washington, D.C. There are ten NASA centers all over the United States. There are also seven test and research facilities. More than 18,000 people work for NASA! Being an astronaut is probably the best-known job at NASA, but astronauts make up just a small part of the workforce. A lot of engineers and scientists work at NASA. People are doing other jobs, too, such as secretaries, writers, lawyers and even teachers.
What Has NASA Done?
From its start, NASA began to plan for human spaceflight. The Mercury, Gemini and Apollo programs helped NASA learn about flying in space. This led to the first human landing on the moon in 1969. Right now, NASA is working to finish the International Space Station. Space probes have visited every planet in the solar system. Scientists have looked far into space using telescopes. NASA satellites help people better understand weather patterns on Earth. NASA also helps develop and test new aircraft. Some of the airplanes have set new records. NASA works to make air travel faster and safer.
What Are NASA's Future Plans?
NASA is beginning a new program. Engineers are planning new rockets and a new spacecraft. That new spacecraft is called Orion. At first, Orion will take astronauts to the International Space Station. Later, it will be used to send astronauts back to the moon. By 2020, NASA plans for astronauts to have landed on the moon. They will set up an outpost there. That outpost will help NASA learn about living on other worlds. NASA will use what is learned on the moon to send humans to Mars. In the future, astronauts will travel even farther into the solar system.
http://www.nasa.gov/audience/forstudents/k-4/stories/what-is-nasa-k4.html
"Noah's Flood" Not Rooted in Reality, After All?
"Noah's Flood" Not Rooted in Reality, After All?
Bruce Dorminey, for National Geographic News
February 6, 2009
The ancient flood that some scientists think gave rise to the Noah story may not have been quite so biblical in proportion, a new study says.
Researchers generally agree that, during a warming period about 9,400 years ago, an onrush of seawater from the Mediterranean spurred a connection with the Black Sea, then a largely freshwater lake. That flood turned the lake into a rapidly rising sea. (See a map of the region).
A previous theory said the Black Sea rose up to 195 feet (60 meters), possibly burying villages and spawning the tale of Noah's flood and other inundation folklore.
But the new study—largely focused on relatively undisturbed underwater fossils—suggests a rise of no more than 30 feet (10 meters).
New Flood Evidence
Marine geologist Liviu Giosan and colleagues carbon-dated the shells of pristine mollusk fossils, which the researchers say bear no evidence of epic flooding.
Found in sediment samples taken from where the Black Sea meets the Danube River, the shells "weren't eroded, agitated, or moved," said Giosan, of the Woods Hole Oceanographic Institute in Massachusetts. "We know the mud is exactly the same age as the shells and so can determine what the sea level was about 9,400 years ago."
The results suggest the Black Sea rose 15 to 30 feet (5 to 10 meters), rather than the 150 to 195 feet (50 to 60 meters) first suggested 13 years ago by Columbia University geologist William Ryan and colleagues. Ryan declined to be interviewed for this story.
Dueling Theories of Noah's Flood
In 1993 a Black Sea expedition found evidence of former shorelines and coastal dunes at depths of up to 390 feet (120 meters).
Researchers said these areas had been flooded when the Mediterranean and the Sea of Marmara—which lies between the Mediterranean and the Black Sea—breached a rocky barrier across the Bosporus, the Turkish strait that links the Maramara with the Black Sea.
Before such a flood, Ryan and colleagues said the flooded regions may have been rife with agricultural settlements. His research supports the notion that the flood submerged some 62,000 square miles (100,000 square kilometers), driving out farmers in droves, thereby supercharging the agricultural development of Europe, to the west.
However, Giosan's new study, which appears in the January issue of the journal Quaternary Science Reviews, indicates a less catastrophic influx, submerging only about 1,240 square miles (2,000 square kilometers).
That's because, according to the new study, the Black Sea's pre-flood water levels were significantly higher than Ryan's study suggested. As a result, there may have been much less water cascading through the Bosporus and onto the exposed continental shelf surrounding the Black Sea.
The ages of the shell fossils detailed in Giosan's report hint that the pre-flood sea surface was only 95 feet (30 meters) lower than it is today. Columbia's Ryan, by contrast, suggests the Black Sea's rise has been at least 150 feet (50 meters) since reconnecting with the Mediterranean some 9,400 years ago.
Nail in Noah's-Flood Coffin?
Giosan's analysis points to a reconnection that was "quite mild," said Mark Siddall, an oceanographer at the University of Bristol in the U.K. who was not involved with the study.
"It looks like the connection may have involved an overspill from the Sea of Marmara of just a few meters," Siddall added.
Tony Brown, a paleo-environmentalist at the University of Southampton in the U.K., said he fully supports Giosan and colleagues' new findings.
"This seems to be a further nail in the coffin of the Ryan hypothesis," Brown said.
"I hope this will counter some recent catastrophist and misguided accounts of the spread of farming across Europe by what is likely a mythical flood."
New Swarm Theory: The Weak Can Lead the Strong
New Swarm Theory: The Weak Can Lead the Strong
Ker Than, for National Geographic News
February 11, 2009
They might not win many presidential elections, but mavericks are often leaders among flocks of birds, herds of beasts, and other creatures, a new swarm theory says.
A new computer model suggests animals don't need to be fast or strong to lead their swarms, only willing—or desperate enough—to break from their neighbors and go their own way.
Swarm "leaders are not necessarily the weakest and most vulnerable, but they can be," said study team member Larissa Conradt of University of Sussex in the United Kingdom.
The model suggests that a few very hungry birds in a well-fed flock of thousands can alter the flight path of their entire group simply by veering off to search for food.
Creatures that fly, swim, and run together are hardwired to stay together, Conradt explained.
Swarm living provides protection against predators and a convenient supply of potential mates, so members rarely perform actions that could tear the group apart.
"If some group members are desperate to reach their optimal destination, while others care relatively less whether they reach theirs or not, the desperate ones will lead," said Conradt, whose new research will be detailed in an upcoming issue of the journal American Naturalist.
Biologist David Sumpter studies collective animal behavior at Uppsala University in Sweden and did not participate in the research.
The new study is interesting, Sumpter said, because it shows how "a small number of highly motivated leaders can manipulate the group dynamics significantly for their own purposes but without destroying the cohesive motion of the flock."
From: http://news.nationalgeographic.com/news/2009/02/090211-swarm-theory-leaders.html
