Fungi

	An Introduction to Fungi
The golden mushroom (Flammulina velutipes) grown using a home cultivation kit.

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Unlike bacteria, fungi are eukaryotes (i.e. their cells contain complex organelles such as nuclei which are also found in animal and plant cells). Although some fungi may superficially resemble plants recent molecular evidence suggests that fungi are probably more closely related to animals. Most fungi grow in the form of microscopic filaments called hyphae that extend and branch at their tips to form a vast network or mycelium. The familiar field and forest mushrooms are the fruiting structures that arise from such a network. To exploit new habitats fungi have to produce countless millions of spores since very few of these spores will successfully form new colonies. With gilled mushrooms the spores are produced on the surface of the gills. These delicate structures serve to increase the surface area available for the production of spores and are protected by the more robust cap. The presence or absence of a volva and ringare important characteristics used for identifying these types of fungi. Some species have pores, spines or blunt ridges instead of gills. However, the reproductive structures of many fungi do not have the characteristic mushroom shape at all and range in size from the giant puffball to the tiny conidiogenousstructures of moulds.

Classification of Fungi

The larger fungi are divided into two main groups (phyla) based on the way that they produce their spores. The Ascomycota produce their spores inside a long cell called an ascus. The Basidiomycota form their spores externally on a club-like cell called a basidium.

Role in nature

Fungi play a vital role in nature. Many are saprotrophs, living on dead organic matter such as leaf litter and have an important role in re-cycling. Others form symbiotic associations with trees and other plants (mycorrhizal fungi) which extend the plant root system assisting in the uptake of water and nutrients. Over 90% of plants have a fungus associated with their roots and many would not survive without their fungal partner. It has also been estimated that over 1000 species of insects and other creatures in the UK alone are dependent on fungi for food and shelter.

Applications of fungi

Some of the most important organisms used in biotechnology are fungi. Brewing and baking have been carried out for thousands of years and both are dependent on the conversion of sugar into alcohol and carbon dioxide by yeasts. In this century fungal fermentation has been harnessed to manufacture important therapeutic compounds, such as antibiotics and the cyclosporins used for preventing rejection of human organ transplants. Many enzymes are produced from fungi for use in the food, textile and other manufacturing industries. Indoor cultivation of edible mushrooms is a multi-billion dollar industry but so far limited to saprotrophic species.

 

Fungi growing in laboratory scale bioreactors at BTTG.

Number of species

In view of the importance of fungi it may be surprising to learn that it is not possible to say with any certainty how many species occur in a particular locality. Fungi differ from plants in that, with the exception of perennial species like some brackets, it is not possible to predict when or whether their fruiting structures will appear from year to year. They are also very easy to miss since most species produce fruit bodies that decay and disappear within a few days. The potential number of species that have to be considered when examining an unknown fungus does not help with identifications. For example, Pegler & Spooner (1992) estimate that there are more than 8,000 species of the larger fungi (i.e. fungi having fruit bodies large enough to pick and examine with the naked eye) in North America and Europe while Courtecuisse & Duhem (1995) describe 3,500 species in their field guide to the fungi of Britain and Europe. To put these figures in perspective consider the total number of birds or plants recorded in the UK given in the table below:

	Number of species recorded in the UK	Reference
Birds	552 (category A, B, C species)	British Ornithologists' Union
Mosses and Liverworts	1034 (including varieties)	Mosses and Liverworts in Wales
Wild flowers	2300 (approximate number)	The Wild Flower Page

The lack of knowledge about local fungal populations needs to be addressed since many types of fungi, especially those that grow in association with trees, appear to be in decline. For example, in Germany’s Black Forest once common species, such as chanterelles, are now reported to be completely absent. Recent concern has been expressed about the effects of commercial collection of edible wild fungi on fungal populations but the real culprit is probably pollution (Rotheroe, 1998). Loss of habitat is also of increasing concern.

Recording fungi

Recording of fungi is largely carried out by amateur mycologists in the UK. Although non-professional, many are expert field mycologists and most belong to local fungus recording groups who collect all the records together and produce distribution maps for their area. A selection of dot distribution maps from the Common Fungi Survey carried out by the North West Fungus Group are available from a site maintained by John Edmondson, Curator of Botany at Liverpool Museum. At a national level records are collated by the British Mycological Society (BMS) and put on the BMS Foray Records Database.

A list of the most frequently recorded fungi in our region is available as a text file from John Taylor's site.

Endangered species

A provisional list of nationally endangered species and some notes on locally (Northwest England) rare species is available from Mike Walton's site.

Guidance on the collection of fungi

On 4 September 1998 English Nature published the first ever Wild Mushroom Pickers' Code of Conduct in the UK and it can be viewed on-line thanks to the British Mycological Society. You should read this document before collecting fungi for scientific study or for the pot.

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Fungi are not plants.

Living things are organized for study into large, basic groups called kingdoms. Fungi were listed in the Plant Kingdom for many years. Then scientists learned that fungi show a closer relation to animals, but are unique and separate life forms. Now, Fungi are placed in their own Kingdom.

It is a hidden kingdom. The part of the fungus that we see is only the “fruit” of the organism. The living body of the fungus is a mycelium made out of a web of tiny filaments called hyphae. The mycelium is usually hidden in the soil, in wood, or another food source. A mycelium may fill a single ant, or cover many acres. The branching hyphae can add over a half mile (1 km) of total length to the mycelium each day. These webs live unseen until they develop mushrooms, puffballs, truffles, brackets, cups, “birds nests,” “corals” or other fruiting bodies. If the mycelium produces microscopic fruiting bodies, people may never notice the fungus. 

Most fungi build their cell walls out of chitin. This is the same material as the hard outer shells of insects and other arthropods. Plants do not make chitin.

Fungi feed by absorbing nutrients from the organic material in which they live. Fungi do not have stomachs. They must digest their food before it can pass through the cell wall into the hyphae. Hyphae secrete acids and enzymes that break the surrounding organic material down into simple molecules they can easily absorb. 

Fungi have evolved to use a lot of different items for food. Some are decomposers living on dead organic material like leaves. Some fungi cause diseases by using living organisms for food. These fungi infect plants, animals and even other fungi. Athlete’s foot and ringworm are two fungal diseases in humans. The mycorrhizal fungi live as partners with plants. They provide mineral nutrients to the plant in exchange for carbohydrates or other chemicals fungi cannot manufacture.

You probably use fungal products every day without being aware of it. People eat mushrooms of all shapes, sizes and colors. Yeasts are used in making bread, wine, beer and solvents. Drugs made from fungi cure diseases and stop the rejection of transplanted hearts and other organs. Fungi are also grown in large vats to produce flavorings for cooking, vitamins and enzymes for removing stains.

GLOSSARY

• hyphae (hí - fee) plural: the threads that form the body of a fungus (mycelium)
• mycelium (my - sée - lee - um): see hyphae
• mycorrhiza (my - koh - rý - zuh) singular; mycorrhizae (my - koh - rý - zee) plural: a beneficial combination between a fungus and a living plant root
• symbiosis (sim - by - óh - sis) singular; symbioses (sim - by - óh - sees) plural: a partnership formed between two living organisms.

Gemstones

Gifts from the Earth:
Where Do Gemstones Come From? 

For thousands of years humans have collected, hoarded, traded, stolen and looted cut and polished stons of various sorts. By far, the stones most highly prized by cultures around the world are those we classify asgemstones. Wars have been waged, and families torn apart by their allure while the mystique and power we have imbued in these glittering stones have spawned legends. Unmatched beauty, purity, rarity, and endurance are the ultimate qualities of the most highly prized gemstones. Join us as we profile the rarest and most precious of gemstones and explore the geologic processes that forge them...

Click on any of the images to see the source and find more fascinating information about these beautiful gems

Corundum
Al2O3; Aluminum Oxide

This is not a mineral you often hear about, but it is the second hardest natural mineral known to man. Aluminum Oxide, as it is known in mineralogy circles, is formed by both volcanic processes deep in the earth and the high pressure and temperature, conditions of metamorphic processes. As liquid magma deep within the earth slowly cools the minerals dissolved within cool into crystals. The purest and most translucent forms of corundum are created by recrystallization of minerals during the metamorphosis of rocks that are of igneous origin. It is a process that takes millions of years and only a few places in the world have rock outcrops where these rare crystals are exposed by weathering.

The pure form of the mineral corundum is clear and colorless, but mineral 'impurities' that seep into the Aluminum Oxide as the rock cools give it its fabulous colors. The distinctive colors of many gemstones are caused by the presence of transition metals as impurities in an otherwise transparent crystal lattice. This is a called crystal-field or, a ligand-field effect. Corundum comes in many different colors, all of which are highly prized if they are free of intrusions and translucent or transparent. When trace amounts of titanium and iron get into the Al2O3 crystal lattice during its formation a beautiful blue sapphir is formed.

ANTARCTICA

Coldest Place.... 
ANTARCTICA

A Really "Cool" Place to Be a Scientist

You want to talk about world records, Antarctica is the land of extremes. It is the coldest, windiest, andhighest continent anywhere on earth. With an average elevation about 7,544ft/2,300 meters above sea level it is the highest continent. Even though it is covered in ice it receives some of the least amount of rainfall, getting just slightly more rainfall than the Sahara Desert, making it the largest desert on earth. Most people have the misconception that a desert is a hot, dry, sandy, lifeless place, but the true definition of a desert is any geographical location that receives very, very little rainfall. Even though there's ice on the ground in Antarctica, that ice has been there for avery long time.

Antarctica is the only continent that has never had an indigenous population of humans because it has always been such an extreme environment. Just the boat ride getting to the continent is over the most treacherous seas anywhere in the world. The inaccessibility of the place and the lack of reliable food and means for constructing shelter has kept humans away for thousands of years. But the new technologies developed over the last 200 years made it possible for people to reach these icy shores to explore and study the Antarctic for the first time in human history.

Since there are no people who claim Antarctica as their homeland, exploration of the continent has been shared by all nations of the world. Scientists from all over the world - Russia, Japan, the United States, United Kingdom, Australia, New Zealand, South America, and many others - come to this place in an internationally cooperative agreement to study the truly unique qualities of Antarctica. Many scientific stations have been constructed on Antarctica to provide shelter and supplies for scientists doing field work there.

Meet a scientist who's been to Antarctica - even went diving under the ice!

Some scientists actually live on Antarctica for part of the year to conduct their research. Very few scientists stay there more than six months at a time. The sun rises and sets only once a year at the South Pole, which means there are six months of daylight, followed by six months of darkness. During the winter when there is no sun, the Antarctic becomes an even more hostile place to be - colder than cold, BONE-CHILLING cold, and no daylight. Can you imagine living in darkness 24 hours a day? That would almost be like living out in space! Hey.....

The World's Biggest Laboratory

At first, the scientific value of studying the Antarctic was just for the sake of understanding this strange place. Recently, scientists have theorized that the conditions in the Antarctic are similar to those on Mars. Because of the similarities exploration of the Antarctic has taken on a new meaning for the search for signs of life in the most extreme environments. Antarctica is not only fascinating itself, but serves as an excellent laboratory for studying the effects of space travel, developing new technologies for exploring other planets and finding extraterrestrial (yeah, alien) life.

Many, many fascinating things have been discovered in the Antarctic that have challenged some of our most basic ideas about what life on earth means. Some really cool factoids:

Deepest Earth Depression: The lowest point on earth is located in the basin of the Bentley Subglacial Trench. At -2,555 meters (8,325 feet) below sea level it is the world's lowest elevation not under seawater. It is not accessible because it is buried under the thickest ice yet discovered.

90% of the ice on earth is located in Antarctica. There is so much ice there you could carve up a block of ice the size of the Great Giza pyramid for every human being on the planet! 98% of Antarctica is covered in ice.

Marine Life: Some species of fish that live in the waters around Antarctica are specially adapted to life in near-freezing waters. Most living creatures on this planet have hemoglobinin their blood, which gives it that red color we all know so well. These particular species of fish, however, have extremely low levels of hemoglobin in their blood. So low that their blood isn't even red! They also have natural antifreeze in their bodies to protect them from freezing to death. (Even if you're a fish and the water in all the cells of your body freezes and turns to ice crystals, you die. 'Nuff said). If you were to catch one of these fish and cut it open the blood, gills and all the organs would be WHITE.

Weather: Yes, the Antarctic has the coldest temperatures on the earth, but that shouldn't surprise you. (Coldest reported temperature ever was -89.4°C/-129°F.) What most people don't know is that the South Pole has the clearest, calmest weather anywhere on earth. Most of the wickedly high winds that everyone associates with the cold and the ice of the Antarctic are around the edges of the continent at the shores. These winds are so fast and so fierce they are world-famous and they have a special name, too - katabatic winds - and they can blow with hurricane force up to 304kmh/190 mph!

Believe it or not with all the ice in the Antarctic, there is very little actual snowfall or precipitation. It does snow on the ice during the austral winter, but measured on an annual basis the Antarctic is as dry as the Sahara Desert.

Antarctic Ice - The Ultimate Cool

Many scientists study Antarctic ice because it is more than just ice. It has accumulated over time, layer upon layer, building up over the millennia to create a type of sedimentary rock. Yes, rock. Ice crystals can be considered a type of mineral, and glacial ice is composed of crystals of the "mineral" water. Just like sedimentary rock is created over time by the repeated layering of particles of clay or sand, glacial ice builds up over millions of years by the build up of snow that never melts.

Scientists drill down deep into the ice with a drill that works kind of like a cookie cutter, only it cuts out somereally deep cookies of ice. These core samples contain many layers of ice that represent what the earth's atmosphere was like at the time each layer of ice was formed. By studying the layers of ice in the core samples scientists can learn about how the earth's atmosphere has changed over geologic time.

In the winter time the ocean around Antarctica freezes for thousands of miles in all directions. This vast expanse of ice surrounding the already immense Antarctic ice sheet covers over eleven million square kilometers. The annual freezing of the ocean around Antarctica generates deep ocean currents worldwide. Differences in ocean temperature are what cause weather all over the globe. Some scientists fear that if the global climate gets too warm or too cold it could affect the formation of Antarctic ice, changing the climate as we know it all over the world.

How Plate Tectonics Works

How Plate Tectonics Works

Way back in 1912 a scientist by the name of Alfred Wegener came up with a crazy idea. He noticed that all of the continents seemed to fit together like the pieces of a giant puzzle. He thought, "Maybe they were once all joined together in a single, giant landmass that broke up and drifted apart over time?". He decided to give this supercontinent a name and called it Pangea, meaning, "all lands". At the time he presented his idea to the scientific community it came to be known as continental drift theory. Wegener was unable to find solid evidence to support his theory, so the other scientists laughed him off as a crackpot. One of his suggestions for the cause of continental drift was thatcentrifugal force from the rotation of the earth caused the continents to slide into each other and move around on the surface. They all calculated that there wasn't enough force generated by the earth's rotation to cause shifting of the crust and nobody took him seriously. They were all convinced the earth was rock-solid and immovable.

But then in 1929, along came a scientist named Arthur Holmes who didn't think that Wegener's theory of continental drift was too farfetched. "Now wait just a minute. Maybe he's got something here", he told them. He mentioned one of Wegener's other theories about the source of continental drift; the idea that the molten mantle beneath the earth's crust experiences thermal convectionand that the movement of these convection currents in the mantle could cause an upwelling beneath the crust, forcing it to break apart and move. Now, that sounded like a semi-reasonable explanation for the movement of the earth's crust. As a matter of fact, if you looked closely at this idea it explained a lot of things, not just the continental puzzle idea. It also explained how mountain ranges were formed - by continents crashing into each other and 'rumpling up rock'. Still, the other scientists just nodded and said, 'Yeah. Fine. Whatever'. And the theory was neatly tucked away and ignored.

Scientists are trained to be skeptical. They were all waiting for a preponderance of evidence that backed up this harebrained theory.

Over the next thirty years a lot of new and surprise discoveries were made as new technologies were developed for exploring the ocean floor . The discovery of volcanic activity on the ocean floor in the middle of the Antlantic that turned out to be part of a long, unbroken mountain chain of undersea volcanoes was the most ground-breaking discovery that supported the theory of continental drift. Scientists developed instruments for measuring earthquakeactivity around the world and began plotting the locations of earthquakes. They all got together and started drawing a new map of the world that showed volcanic and seismic (earthquake) activity was concentrated along certain areas that looked like the margins of huge crustal plates. During the 1960s several scientists published papers that reviewed the preponderance of evidence that had been gathered for the theory of continental drift and it soon came to be known as the theory of plate tectonics. The evidence that supports the theory consists of the following discoveries;

Mid-ocean Ridges
A spreading boundary is where the tectonic plates are separating. Some spreading boundaries are places where the crust is sinking downward as it is stretched thin - like in the East Rift Valley of Africa, where the Dead Sea is located. Many of the spreading boundaries are located deep in the ocean on the sea floor. These are places where volcanic activity is at a premium because the crust is being torn apart. New crust is forming when magma from the mantle deep down is forced upward out of the cracks where the plates are coming apart. Long chains of undersea mounts (the world's longest is the mid-Atlantic Ocean Ridge) and volcanic islands typically characterize these type of plate margins.

Geomagnetic Anomalies
New rock formed from magma records the orientation of Earth's magnetic field at the time the magma cooled. By collecting and measuring samples of rock from various locations along the Mid-Atlantic Ridge, scientists have discovered that the newest, youngest crustal rocks are located in the center of the ridge, while the rocks get older as you move away from the ridge center. This supports the idea that oceanic crust continues to be pulled apart, while new crust is formed along the edges of the plates.

Deep Sea Trenches
At the same time, some of the oldest ocean crust occurs in deep sea trenches, which run parallel to continental mountain ranges. A lot of very large earthquakes have been plotted along deep ocean trenches, suggesting that these are seismically active areas (meaning the crust is moving). Scientists put two and two together, noting that the youngest oceanic crust was along the mid-ocean ridges and the oldest ocean crust was along the very bottoms of deep sea trenches. That neatly defined the edges of the tectonic plates and showed the direction of their movement. Where the deep sea trenches were found came to be called converging boundaries.

A converging boundary is the opposite of a spreading boundary. Typically you will see a converging boundary on a tectonic plate that is on the opposite side of a spreading boundary. As a plate moves in one direction it collides with the adjacent plate on its "front" end in a deep sea trench, while the trailing end of the plate is being pulled and stretched (spreading) from the plate on the other end at a mid-ocean ridge. For example, look at the Pacific plate. The entire plate is moving north and westward as the top edge converges with the North American and European plates. You can see the left side of the Pacific plate is converging with the Indian plate. Then if you look at the bottom and right edges of the plate you can see it's spreading apart from the Antarctic and Nazca plates.

Sometimes you'll see volcanic activity at converging boundaries where plates are crashing into each other. When one plate (usually the lighter continental crust) rides up over the top of the other it's called a subduction zone - because one plate margin is being subducted under the other.

A good example of this type of plate margin is where the Nazca and South American plates are crashing into each other. The lighter continental South American plate is riding up over the heavier oceanic Nazca plate. Deep down where the leading edge of the Nazca plate is diving down under the South American plate it's making contact with the molten magma of the earth's mantle. The long cordillera, or chord-like chain of volcanic mountains known as the Andes, are a result of the rumpling of the South American plate where the Nazca plate crashes into it, and the volcanoes that have formed from the increased seismic activity on the Nazca plate margin deep down.

In other converging boundaries, there is no volcanic activity because the tectonic plates are both continental plates, weighing the same. No subduction happens along these margins, just massive deformation of the edges of the plates. A good example of this is the Himalayan Mountains where the European and Indian plates meet. The two plates have continued ramming into each other, causing the crust to buckle, wrinkle, and uplift into thehighest mountain range on earth.

The few transverse boundaries are places where the two plates are just sliding past each other. In many of these boundaries there is a lot of tension and strain where the two plates are sliding and scraping past each other. The resulting strain from the sliding action of the plates causes cracks in the crust called faults. As the larger plates move past each other some chunks of crust and overlying rock are broken into fault blocks. When there is a big enough movement along the cracks or faults in the earth's crust we feel it in the form of earthquakes.

One of the most famous faults is the San Andreas, which runs along the west coast of California. It's famous for generating many of the larger quakes in California, including the world-renowned San Francisco earthquake of 1906. Funny thing is, the 1906 earthquake itself didn't do nearly as much damage as the fires that burned the city afterwards - all the water mains had burst and broken during the 'quake so there was no water to put out the fires!

Hot Spots

About 30 years ago a Geophysicist named J. Tuzo Wilson came up with an idea to explain why there was volcanic activity out in the middle of the Pacific Ocean, in the middle of the huge Pacific Plate. At the time, scientists thought that volcanoes only happened at plate boundaries, but nobody could explain why they were happening out in the middle of a tectonic plate. Dr. Wilson said that there are "hot spots", under the earth's crust in some places. These are called hot spots because they are places where a lot of heat is concentrated in a small area. The heat causes the overlying rock to melt. Since the magma is liquid and is lighter than the surrounding rock it "floats" to the surface and forces its way out of fissures in the crust. once magma erupts through the crust it is known as lava. Over time, the continual outpouring of lava can form a sea mount or island volcano if the hot spot is under the ocean floor, as in the case of the Hawaiian Islands. There is just one hot spot that never moves. But the Pacific Plate continually (and slowly) moves north over the hot spot, forming a new volcano on the overlying plate each time.

Doing the Science

Scientists had a lot of questions about why there were volcanic islands way out in the middle of the Pacific plate. It just didn't seem to fit in with their theory of plate tectonics. Dr. Wilson's idea of hot spots helped the island volcanoes to fit into the theory of plate tectonics. If the Pacific plate was moving over a hot spot, then that would explain why a chain of sea mounts and volcanoes had formed as the plate moved. If this was true, then the volcanoes should be of different ages, from oldest to youngest in a single direction.

In order to test his theory, Dr. Wilson took samples of volcanic rock from each of the volcanic islands in the Hawaiian chain and tested them to see how old they were on a geologic time scale. He found that the oldest rocks were from the northernmost island of Kauai, which also had the most weathering of rock. He also found that progressively younger rocks were found on the Hawaiian islands the further south he went (see map). The youngest rocks of all were found on the big island of Hawaii, the southernmost island. In fact, new "rocks" are still forming on the island of Hawaii, making it the youngest volcano in the island chain. There is even more evidence to support his theory because there is a new volcano forming on the sea floor south of Hawaii, called Loihi. Right now it's just a sea mount, but if the lava continues to build up on its slopes, someday it will be a new island.

Read about a scientist who "chases" volcanoes

Life in the Deep

Life in the Deep

Many species of deep ocean fish have special adaptations to living in extremely high pressure, low light conditions. Viper fish(Mesopelagic - found at 80-1600 meters - about a mile down) are some of the most wicked looking fish dredged up from the depths. Some of them are black as night all over with light organs (calledphotophores) in strategic places on their bodies, including one on a long dorsal fin that serves as a lure for the fish it preys upon. Some viperfish (and many other deep ocean fish species) don't have anypigment (color) at all - they're "see through". They also have enlarged eyes, presumably for gathering as much light as possible where there is little or no light at all. The light organs create lights by using a chemical process called bioluminescence. Other deep ocean fish, such as the the gulper eel

have a hinged skull, which can rotate upward to swallow large prey. They also have large stomachs which can stretch to accommodate a fish much larger than itself. The gulper eel is particularly well-known for its impossibly large mouth - big enough to get its mouth around (and swallow!) creatures much bigger than itself. Fish that live down here must adapt to a very low food supply, eating only "scraps" that sink down from above, or sometimes eating each other.

Here's an up close and personal view of the wicked-looking Viper fish (Chauliodus macouni). Check out the teeth and the bug eyes on this guy! Click on the photo to see a much larger picture...
(photo courtesy of Paul Yancey,
Biology Dept., Whitman College, 
Walla Walla Washington)

 

A Fangtooth - scientists still aren't exactly sure why so many bony fishes of the deep have such enlarged, daggerlike teeth.

GREAT WHITE SHARK

Biggest Carnivorous Fish...
GREAT WHITE SHARK

Solitary Leviathans 
Great white sharks are still a mystery, as scientists are still trying to unravel the lifestyle of these denizens of the deep. They are solitary creatures roaming the ocean in constant search of food. Scientists are still unsure how to tell the age of a great white shark or how long they live, how often and where they breed, and how quickly they grow.

It is widely held among shark experts that the great whites take a long time to reach the fearsome proportions of record and that over fishing of these incredible creatures has led to a rapid decline in their numbers. No one knows how long it would take for the world's great white shark numbers to rebound if we were to completely halt fishing of this species. We are now beginning to realize the important role they play in their ecosystem, eliminating the weak and the sick from their environment and keeping seal and sea lion numbers in check. Lack of great white sharks to control the sea lion population may be one of the contributing factors to the declining salmon populations along the coast of California and Oregon.

What scientists have been able to study in great whites is their predatory and feeding behavior. In the Farallon Islands, off the coast of California, scientists are videotaping and documenting attacks on pinnipeds (seals and sea lions - the sharks' favorite prey) to understand how these awesome killing machines operate. By studying shark attack behavior, scientists hope to understand and predict how and when a great white will attack. People who "use" the ocean can use this information to protect themselves from being attacked by a great white shark.

Expert Killing Machines

The teeth of the great white are perfectly designed for slashing flesh and mortally wounding prey with a minimum of effort. If a tooth is lost during an attack, another quickly grows forward to replace it.

Great white sharks have a number of adaptations (behaviors and anatomical features) that make them such efficient killers:

For sensing - specialized sensory organs called ampullae of Lorenzini located in the shark's snout, which can detect electrical currents of as little as .005 millivolts that are generated by every living creature in the water

Extremely acute and sensitive sense of smell, allowing the great white to detect the most miniscule amounts of blood in the water up to 5km away - blood means injured victim = less effort required for the meal (Efficiency!)

For stalking - the coloring of the great white makes for excellent camouflage in the ocean - dark above, and light below makes it difficult to be detected while swimming on the bottom (great whites strike from below)

For striking - a large, powerful body and specially designed tail that provides for enormous bursts of energy for striking with such tremendous strength that the first bite is frequently a death blow

Several rows of razor sharp teeth that are continually replaced to ensure an entire jaw of efficient, lacerating implements

Scientists who study the Great White Shark have found that when attacking their prey, the strategy of the great white is usually to strike from below in one powerful blow (some human shark attack victims have likened the experience to being hit by a car), inflicting a lethal bite to head or trunk of its victim. The shark then swims away a short distance to let its victim bleed to death so that it will not have to struggle with its meal. This brief respite after the initial chomping is what allows many human victims (but not all) to escape being eaten alive by the great white predator.

Other Great Sharks

The largest great white on record measured 21 feet long. Some claim a 23 footer was caught in the Mediterranean, but that report has not been authenticated. Since great whites are such elusive and mysterious creatures, it's entirely possible there may be even bigger ones out there we have yet to meet.

Paleontologists have found the fossilized jaws of an ancient ocean predator that is an ancestor of the great white, called Charcharodon megalodon. The size of the jaws indicate the size of the creature may have been as large as 50 feet long! Some scientists argue that it's possible these monsters still exist in the ocean deeps, that we just haven't found them yet.

Read about the world's deadliest creature!

There are other large species of living sharks that have reputations for ferocity that rival the great white. The bull shark, white tip reef sharks, blue sharks, tiger sharks, seven gill sharks, and some monsters of the deep that can get up to 20 feet long - sleeper sharks and primitive six gill sharks. These species of sharks may rival the ferocity of the great white, but none of them have been found to grow as large. Carcharodon carcharias holds the world record for largest carnivorous fish, but there are even bigger ocean predators than the Great White roaming the ocean...

Greatest River....

Greatest River.... 
AMAZON

How Great is the Amazon River?

The Amazon is the greatest river in the world by so many measures; the volume of water it carries to the sea (approximately 20% of all the freshwater discharge into the oceans), the area of land that drains into it, and its length and width. It is one of the longest rivers in the world and, depending upon who you talk to, is anywhere between 6,259km/3,903mi and 6,712km/4,195mi long.

For the last century the length of the Amazon and the Nile Rivers have been in a tight battle for title of world's longest river. The exact length of the two rivers varies over time and reputable sources disagree as to their actual length. The Nile River in Africa is reported to be anywhere from at 5,499km/3,437mi to 6,690km/4,180mi long. But there is no question as to which of the two great rivers carries the greater volume of water - the Amazon River.

At its widest point the Amazon River can be 11km/6.8 mi wide during the dry season. The area covered by the Amazon River and its tributaries more than triples over the course of a year. In an average dry season 110,000 square km of land are water-covered, while in the wet season the flooded area of the Amazon Basin rises to 350,000 square km. When the flood plains and the Amazon River Basin flood during the rainy season the Amazon River can be up to 40km/24.8 mi wide. Where the Amazon opens at its estuary the river is over 325km/202 mi wide!

Because the Amazon drains the entire Northern half of the South American continent (approx. 40% landmass), including all the torrential tropical rains that deluge the rainforests, it carries an enormous amount of water. The mouth of the Amazon River, where it meets the sea, is so wide and deep that ocean-going ships have navigated its waters and traveled as far inland as two-thirds the way up the entire length of the river.

 

The Amazon - Home of Extremes 

The Amazon River is not only the greatest in the world, it is home to many other "Extremes" of the natural world. Have you ever seen a catfish? They're usually found in warm, slow moving waters of lakes and streams, and some people keep them as pets in aquariums. Catfish are pretty creepy looking fish with big flat heads and "whiskers" on either side of their heads (hence the name, catfish). Most catfish that we're familiar with here in the U.S. are anywhere from eight inches long to about five feet, weighing in at up to 60 pounds. But the catfish that live in the world's greatest river have all the room in the world to grow as big as nature will allow - they have been captured weighing over 200 pounds! One of the largest freshwater fish in the world is found living in the waters of the Amazon River. Arapaima, also known locally as Pirarucu, Arapaima gigas are the largest, exclusively fresh water fish in the world. They have been found to reach a length of 15 ft/4m and can weigh up to 440lbs/200kg. (Read about the biggest freshwater fish in the world.)

Moon

The Moon is the only natural satellite of Earth:

        orbit:    384,400 km from Earth         diameter: 3476 km         mass:     7.35e22 kg

Called Luna by the Romans, Selene and Artemis by the Greeks, and many other names in other mythologies.

The Moon, of course, has been known since prehistoric times. It is the second brightest object in the sky after the Sun. As the Moon orbits around the Earth once per month, the angle between the Earth, the Moon and the Sun changes; we see this as the cycle of the Moon's phases. The time between successive new moons is 29.5 days (709 hours), slightly different from the Moon's orbital period (measured against the stars) since the Earth moves a significant distance in its orbit around the Sun in that time.

Due to its size and composition, the Moon is sometimes classified as a terrestrial "planet" along with Mercury, Venus, Earth andMars.

The Moon was first visited by the Soviet spacecraft Luna 2 in 1959. It is the only extraterrestrial body to have beenvisited by humans. The first landing was on July 20, 1969 (do you remember where you were?); the last was in December 1972. The Moon is also the only body from which samples have been returned to Earth. In the summer of 1994, the Moon was very extensively mapped by the little spacecraft Clementine and again in 1999 by Lunar Prospector.

The gravitational forces between the Earth and the Moon cause some interesting effects. The most obvious is thetides. The Moon's gravitational attraction is stronger on the side of the Earth nearest to the Moon and weaker on the opposite side. Since the Earth, and particularly the oceans, is not perfectly rigid it is stretched out along the line toward the Moon. From our perspective on the Earth's surface we see two small bulges, one in the direction of the Moon and one directly opposite. The effect is much stronger in the ocean water than in the solid crust so the water bulges are higher. And because the Earth rotates much faster than the Moon moves in its orbit, the bulges move around the Earth about once a day giving two high tides per day. (This is a greatly simplified model; actual tides, especially near the coasts, are much more complicated.)

But the Earth is not completely fluid, either. The Earth's rotation carries the Earth's bulges slightly ahead of the point directly beneath the Moon. This means that the force between the Earth and the Moon is not exactly along the line between their centers producing a torque on the Earth and an accelerating force on the Moon. This causes a net transfer of rotational energy from the Earth to the Moon, slowing down the Earth's rotation by about 1.5 milliseconds/century and raising the Moon into a higher orbit by about 3.8 centimeters per year. (The opposite effect happens to satellites with unusual orbits such as Phobos and Triton).

The asymmetric nature of this gravitational interaction is also responsible for the fact that the Moon rotatessynchronously, i.e. it is locked in phase with its orbit so that the same side is always facing toward the Earth. Just as the Earth's rotation is now being slowed by the Moon's influence so in the distant past the Moon's rotation was slowed by the action of the Earth, but in that case the effect was much stronger. When the Moon's rotation rate was slowed to match its orbital period (such that the bulge always faced toward the Earth) there was no longer an off-center torque on the Moon and a stable situation was achieved. The same thing has happened to most of the other satellites in the solar system. Eventually, the Earth's rotation will be slowed to match the Moon's period, too, as is the case with Pluto and Charon.

Actually, the Moon appears to wobble a bit (due to its slightly non-circular orbit) so that a few degrees of the far side can be seen from time to time, but the majority of the far side (left) was completely unknown until the Soviet spacecraft Luna 3 photographed it in 1959. (Note: there is no "dark side" of the Moon; all parts of the Moon get sunlight half the time (except for a few deep craters near the poles). Some uses of the term "dark side" in the past may have referred to the far side as "dark" in the sense of "unknown" (eg "darkest Africa") but even that meaning is no longer valid today!)

The Moon has no atmosphere. But evidence from Clementine suggested that there may be water ice in some deep craters near the Moon's south pole which are permanently shaded. This has now been reinforced by data from Lunar Prospector. There is apparently ice at the north pole as well. A final determination will probably come from NASA's Lunar Reconnaissance Orbiter, scheduled for 2008.

The Moon's crust averages 68 km thick and varies from essentially 0 under Mare Crisium to 107 km north of the crater Korolev on the lunar far side. Below the crust is a mantle and probably a small core (roughly 340 km radius and 2% of the Moon's mass). Unlike the Earth, however, the Moon's interior is no longer active. Curiously, the Moon's center of mass is offset from its geometric center by about 2 km in the direction toward the Earth. Also, the crust is thinner on the near side.

There are two primary types of terrain on the Moon: the heavily cratered and very old highlands and the relatively smooth and younger maria. The maria (which comprise about 16% of the Moon's surface) are huge impact craters that were later flooded by molten lava. Most of the surface is covered withregolith, a mixture of fine dust and rocky debris produced by meteor impacts. For some unknown reason, the maria are concentrated on the near side.

Most of the craters on the near side are named for famous figures in the history of science such as Tycho, Copernicus, andPtolemaeus. Features on the far side have more modern references such as Apollo, Gagarin and Korolev (with a distinctly Russian bias since the first images were obtained by Luna 3). In addition to the familiar features on the near side, the Moon also has the huge craters South Pole-Aitken on the far side which is 2250 km in diameter and 12 km deep making it the the largest impact basin in the solar system and Orientale on the western limb (as seen from Earth; in the center of the image at left) which is a splendid example of a multi-ring crater.

A total of 382 kg of rock samples were returned to the Earth by the Apollo and Luna programs. These provide most of our detailed knowledge of the Moon. They are particularly valuable in that they can be dated. Even today, more than 30 years after the last Moon landing, scientists still study these precious samples.

Most rocks on the surface of the Moon seem to be between 4.6 and 3 billion years old. This is a fortuitous match with the oldest terrestrial rocks which are rarely more than 3 billion years old. Thus the Moon provides evidence about the early history of the Solar System not available on the Earth.

Prior to the study of the Apollo samples, there was no consensus about the origin of the Moon. There were three principal theories: co-accretion which asserted that the Moon and the Earth formed at the same time from the Solar Nebula; fission which asserted that the Moon split off of the Earth; and capture which held that the Moon formed elsewhere and was subsequently captured by the Earth. None of these work very well. But the new and detailed information from the Moon rocks led to the impact theory: that the Earth collided with a very large object (as big as Mars or more) and that the Moon formed from the ejected material. There are still details to be worked out, but the impact theory is now widely accepted.

The Moon has no global magnetic field. But some of its surface rocks exhibit remanent magnetism indicating that there may have been a global magnetic field early in the Moon's history.

With no atmosphere and no magnetic field, the Moon's surface is exposed directly to the solar wind. Over its 4 billion year lifetime many ions from the solar wind have become embedded in the Moon's regolith. Thus samples of regolith returned by the Apollo missions proved valuable in studies of the solar wind

Full Story on the Moon

There's an old saying that the moon is made of green cheese. Of course, that came from a time when people didn't really know what the moon is made of. Scientists have learned a lot about the moon in the last fifty years. Most importantly, we've even traveled to the moon and collected a sample of some of that green cheese. You know what they found? It's not made of cheese at all! It's made out ofrock.

Scientists have theorized about the origin of the moon for centuries, and many implausible theories abound. But there is one very plausible explanation about the birth of the moon, which not only answers where it came from, but explains the earth and moon's rotation and current orbit. Called the Big Impact Theory, it states that the moon was created when another celestial body about the size of mars crashed into the earth. It was such a cataclysmic event that the earth swallowed up the body that crashed into it, absorbing it into its own mass and increasing it to its current size. Another major side effect of the collision was the ejection of a large chunk of earth's rock which was sent into orbit around the earth, becoming its moon.

The rocks that were collected from the moon have been studied extensively for their mineral composition. Examination of "moon soil" samples (called regolith) have revealed some strikingly similarities to earth's geology. Rocks made of basalt from volcanic eruptions and minerals, such as plagioclase feldspar and olivine, are exactly the kinds of rocks we find here on earth. In striking contrast to the true soils that we have here on earth, there are no organic materials in moon dust. Organic materials come from the breakdown of living things, such as trees and animals. Since there's nothing living on the moon, the soil is not a true soil like we're used to here. It's gray with very fine grained particles like sand or even dust and extremely dry because there is no water on the moon. (Although scientists have theorized that there is water ice trapped in the polar regions of the moon). Because the moon has no atmosphere to protect it from solar wind, molecules (like hydrogen, helium, neon, carbon and nitrogen) from the sun impact the moon's surface directly and are implanted into mineral grains. Scientists estimate that about 50% of the moon's surface composition is oxygen, bound up in silicate minerals!

 FULL MOON FACTS

The full moon is a lunar phase occurring when the moon is on the opposite side of the earth from the sun and all three bodies are aligned in a straight line. It appears as an entire circle in the sky.

The only month that can occur without a full moon is February.

The world's tidal ranges are at their maximum during the full moon when the sun, earth and moon are in line.

The full moon is given different names, depending on when it appears:

• January - Moon After Yule, Wolf Moon, or Old Moon
• February - Snow Moon or Hunger Moon
• March - Sap Moon, Crow Moon, Worm Moon or Lenten Moon
• April - Grass Moon, Frog Moon or Egg Moon
• May - Milk Moon or Planting Moon
• June - Rose Moon, Flower Moon, or Strawberry Moon
• July - Thunder Moon or Hay Moon
• August - Grain Moon or Green Corn Moon
• September - Fruit Moon or Harvest Moon
• October - Harvest Moon or Hunter's Moon
• November - Hunter's Moon, Frosty Moon, or Beaver Moon
• December - Moon Before Yule or Long Night Moon.

The Sun The Sun as seen in X-rays (from the Yohkoh satellite) The Sun is a star. It is a rather ordinary star - not particularly big or small, not particularly young or old. It is the source of heat which sustains life on Earth, and controls our climate and weather. It is the closest star to Earth, and the most closely studied. From it we have learned a great deal about the physical processes which determine the structure and evolution of stars in general. Below we discuss the regions of the Sun's atmosphere which we can observe and measure. The Sun's Outer Layers Only the Sun's outer layers, collectively referred to as the solar 'atmosphere', can be observed directly. There are distinct regions to the solar atmosphere: the photosphere, the chromosphere, and the corona. These three regions have substantially different properties from each other, with regions of gradual transition between them. The Photosphere The Sun has basically the same chemicalelements as found on Earth. However, the Sun is so hot that all of these elements exist in the gaseous state. There is not really a "surface" to the Sun. Think of it this way: the Sun is a bunch of gas which gets denser and denser as you move from space toward the solar core. The photosphere would then represent the depth at which we can see no deeper toward the core. Think of what a thick cloud looks like when you look down on it from an airplane - it looks solid, but it isn't. The Parts of a Star The Sun's atmosphere changes from being transparent to being opaque over a distance of only a few hundred kilometers. This is remarkable given the size of the Sun, and represents such a huge change that we often think of it as a true boundary. When we speak of the size of the Sun, we usually mean the size of the region surrounded by the photosphere. The photosphere is slightly different from one place on the Sun to another, but in general is has a pressure about a few hundredths of the sea-level pressure on Earth, a density of about a ten-thousandth of the Earth's sea-level atmospheric density, and a temperature in the range 4500-6000 Kelvin. The Chromosphere The gases which extend away from the photosphere make up the chromosphere. These gases are transparent to most visible radiation. The chromosphere is about 2500 km thick. The density of the gases decreases as you move away from the photosphere into the chromosphere, but the temperature increases! From the bottom to the top of the chromosphere, the average temperature goes from 4500 to 10,000 Kelvin! Needless to say, this rise was not anticipated by scientists when they first measured it. Throughout the rest of the Sun, temperature decreases as you move further away from the core. The Solar Corona seen during a total eclipse The Corona The chromosphere merges into the outermost region of the Sun's atmosphere, the corona. The corona extends for millions of miles into space above the photosphere. Usually, we cannot see the corona because of the brightness of the photosphere. However, during a total solar eclipse, the corona shines beautifully against the dark sky. The corona has a density about 0.0000000001 times that of the Earth's sea-level atmosphere. It is very hot - millions of Kelvin. Because of this high temperature, the bulk of the radiation from the corona is emitted at ultraviolet and X-ray wavelengths. Magnetic fields on the Sun seem to play an important part in heating the gas to such a high temperature. However, the exact way that this happens is not well understood. The image you see to the left was taken during a solar eclipse in 1980; light from the photosphere is blocked out by the Moon (the dark disk). A Few Other Solar Features The Solar Wind The solar wind is nothing more than a stream of charged particles flowing outward from the Sun with an average velocity of about 400 km/sec. It is a natural consequence of the Sun being so hot - the corona gas has too much energy to be gravitationally bound to the Sun. Sunspots and Their Cycle Sunspots are cooler regions on the Sun's photosphere (about 1500 K cooler) and so appear to be darker than the photosphere. A given sunspot can have a lifetime ranging from a few hours to a few months. It consists of two parts - the dark inside region called the umbra and the surrounding less dark region called the penumbra. Their sizes vary over a wide range, with a few having been measured to be 50,000 km in diameter! A German amateur astronomer, Heinrich Schwabe, published a paper in 1851 which stated that the number of sunspots visible on average varied with a period of about 10 years. This conclusion has been substantiated by observations over the 140 years since. The period of repetition on average is 11.1 years, but has been as short as 8 years and as long as 16 years. A plot of the relative number of sunspots as a function of time from 1645 until 1991. During the maximum of the cycle, more than 100 sunspots can be seen on the Sun at once. During the minima, the Sun sometimes has no spots at all. This cycle is closely related to the magnetism of the Sun. In fact, it is the changing magnetic field of the Sun which governs many aspects of solar activity. Life-Giving Star Compared with the billions of other stars in the universe, the sun is unremarkable. But for Earth and the other planets that revolve around it, the sun is a powerful center of attention. It holds the solar system together; pours life-giving light, heat, and energy on Earth; and generates space weather. The sun is a big star. At about 864,000 miles (1.4 million kilometers) wide, it could hold 109 planet Earths across its surface. If the sun were a hollow ball, more than a million Earths could stuff inside it. But the sun isn't hollow. It's filled with scorching hot gases that account for more than 99.8 percent of the total mass in the solar system. How hot? The temperature is about 10,000 degrees Fahrenheit (5,500 degrees Celsius) on the surface and more than 28 million degrees Fahrenheit (15.5 million Celsius) at the core. Deep in the sun's core, nuclear fusion reactions convert hydrogen to helium, which generates energy. Particles of light called photons carry this energy through the sun's spherical shell, called the radiative zone, to the top layer of the solar interior, the convection zone. There, boiling motions of gases (like in a lava lamp) transfer the energy to the surface. This journey takes more than a million years. The sun's surface, or atmosphere, is divided into three regions: the photosphere, the chromosphere, and the solar corona. The photosphere is the visible surface of the sun and the lowest layer of the atmosphere. Just above the photosphere are thechromosphere and the corona, which also emit visible light but are only seen during a solar eclipse, when the moon passes between the Earth and sun. Solar Wind and Flares In addition to light, the sun radiates heat and a steady stream of charged particles known as the solar wind. The wind blows about 280 miles (450 kilometers) a second throughout the solar system. Every so often, a patch of particles will burst from the sun in a solar flare, which can disrupt satellite communications and knock out power on Earth. Flares usually stem from the activity of sunspots, cool regions of the photosphere related to a shifting magnetic field inside the sun. Like many energy sources, the sun is not forever. It is already about 4.5 billion years old and has used up nearly half of the hydrogen in its core. The sun will continue to burn through the hydrogen for another five billion years or so, and then helium will become its primary fuel. The sun will expand to about a hundred times its current size, swallowing Earth and other planets. It will burn as a red giant for another billion years and then collapse into a white dwarf about the size of planet Earth.