My Science School

Freshwater habitats include both still and moving water. Living things within rivers and streams can travel through the water to different areas. Many underwater inhabitants of ponds and Lakes, however, cannot escape from what may be quite a small area of water. However, even a tiny pool may have a complete, self-contained ecosystem. As well as plants and fish, freshwater ecosystems support living things that visit the water but spend part of their lives on land, such as amphibians, birds and insects. Many mammals also spend time in and around the water. Finally, the kinds of wildlife found in freshwater ecosystems will be affected by the climate and landscape around it. For example, the crocodile may be the fiercest predator in an African river, but its place may be taken by an otter in a European stream.

Cast out your fishing line or scoop your net through the water. You are bound to catch something when you are along the river's edge or at the lake. Catching fish is always exciting, but while you wait for that fish to come along.

Freshwater ecosystems include lakes, ponds, rivers, streams, springs, and wetlands. You will find them in many different sizes, from very small to very large. The water within the ecosystem can be still (not moving), like in a pond, or it can be running (moving), like a river or stream.

Freshwater ecosystems are broken into three zones: littoral, open water and deep water - we'll talk more about these below. The plants and animals within the ecosystem interact with light, food, oxygen, weather, and climate in different ways.

Plants and animals grow in different zones in freshwater ecosystems. The littoral (or marsh) zone refers to the plants and animals that grow closest to the edge of the water. The plants in this area can make great hiding spots for animals to hide from predators. You might find snails, clams, or even eggs and larvae from reptiles and insects in this area. Common predators (animals who prey, or feed, on other animals) in this zone include snakes, ducks and swans.

The open water zone refers to plants and animals that live near the top of the water. Some float on top of the water and have tiny roots that go down into the water, like duckweed. Others have their roots down in the mud at the bottom of the pond and leaves that float at the top of the pond, like water lilies. These plants get lots of sunlight, which makes them the top energy producers for the animals in the water. Many fish also swim in this open water zone.

Freshwater ecosystems play a fundamental ecological role and provide economically important products and services. They provide critical habitats for a large number of aquatic plants, fishes, reptiles, birds and mammals. They host many migratory and threatened species of birds, reptiles and fish. The freshwater ecosystems are areas of tourist attraction by providing recreation sites for game and bird watching.

Freshwater ecosystems, especially vegetated wetlands, play an important role in mitigation against climate variability. They do so through a number of ecosystem functions including flood control, water purification, shoreline stabilization and sequestration of carbon dioxide. At landscape level, wetlands control soil erosion and retain sediments and in so doing concentrate nutrients in the wetland soil. They also provide economic benefits such as fresh water, fisheries, fuel-wood, building material, medicinal products, honey and foliage for livestock and wildlife. Wetlands provide fertile land for agricultural, mineral salts, sand and soil for making pottery and building bricks. Wetlands are central to rural subsistence economies and livelihood activities of many rural communities in Kenya. Freshwater ecosystems in general are critical to poverty alleviation and creation of employment and wealth.

Oceans offer various habitats at different depths below the surface. These are called zones. The euphotic zone is at the top, ending at a depth of about 200m (660ft). Below this, very little light from the Sun can reach. The bathypelagic zone below is totally dark, so no plants can live there, but a number of fish, squid and crustaceans do make this zone their home, feeding on waste material that sinks down from above and on each other. Deep-sea creatures cannot see in total darkness, but their other senses help them to find food. Some, such as angler fish, carry their own lights. They are not bright enough to search for food by, but they may lure other fish towards them and help fish of the same species to recognize each other.

When the ancestors of cave fish and certain crickets moved into pitch-black caverns, their eyes virtually disappeared over generations. But fish that ply the sea at depths greater than sunlight can penetrate have developed super-vision, highly attuned to the faint glow and twinkle given off by other creatures. They owe this power, evolutionary biologists have learned, to an extraordinary increase in the number of genes for rod opsins, retinal proteins that detect dim light. Those extra genes have diversified to produce proteins capable of capturing every possible photon at multiple wavelengths—which could mean that despite the darkness, the fish roaming the deep ocean actually see in color.

The finding "really shakes up the dogma of deep-sea vision," says Megan Porter, an evolutionary biologist studying vision at the University of Hawaii in Honolulu who was not involved in the work. Researchers had observed that the deeper a fish lives, the simpler its visual system is, a trend they assumed would continue to the bottom. "That [the deepest dwellers] have all these opsins means there's a lot more complexity in the interplay between light and evolution in the deep sea than we realized," Porter says.

At a depth of 1000 meters, the last glimmer of sunlight is gone. But over the past 15 years, researchers have realized that the depths are pervaded by faint bioluminescence from flashing shrimp, octopus, bacteria, and even fish. Most vertebrate eyes could barely detect this subtle shimmer. To learn how fish can see it, a team led by evolutionary biologist Walter Salzburger from the University of Basel in Switzerland studied deep-sea fishes' opsin proteins. Variation in the opsins' amino acid sequences changes the wavelength of light detected, so multiple opsins make color vision possible. One opsin, RH1, works well in low light. Found in the eye's rod cells, it enables humans to see in the dark—but only in black and white.

Salzburger and his colleagues searched for opsin genes in 101 fish species, including seven Atlantic Ocean deep-sea fish whose genomes they fully sequenced. Most fish have one or two RH1 opsins, like many other vertebrates, but four of the deep-se species stood apart, the researchers report this week in Science. Those fish—the lantern-fish, a tube-eye fish, and two spinyfins—all had at least five RH1 genes, and one, the silver spinyfin (Diretmus argenteus), had 38. "This is unheard of in vertebrate vision," says K. Kristian Donner, a sensory biologist at the University of Helsinki.

To make sure the extra genes weren't just nonfunctional duplicates, the team measured gene activity in 36 species, including specimens of 11 deep-sea fish. Multiple RH1 genes were active in the deep-sea species, and the total was 14 in an adult silver spinyfin, which thrives down to 2000 meters. "At first it seems paradoxical—this is where there's the least amount of light," Salzburger says.

While many fish swim in shoals, eating plankton as they flash through the water, others spend most of their time on the ocean bed. As the fish evolved, their eyes developed on the same side, so that both can see into the water above.

These quick-change artists have eyes on top of their heads, yet marvelously mimic the surfaces they sit on. This prompted Clayton Louis Ferrara to ask Weird Animal. Flatfish have eyes on the top of their heads, how do they see what's going on the ocean floor?”

Flatfish, found all over the world, range from the angler fin whiff which is about three inches (eight centimeters) to the Pacific halibut, which can get up to around nine feet (three meters) long. This fish group includes species familiar to seafood lovers—not only halibut, but flounder, sole, and turbot.

All flatfish have eyes on the end of stalks, so they pop out of the head “kind of like the eyes we saw in cartoons—ba-boing!” 

Flatfish eyes can also move independently, widening their field of vision. Once flatfish eyes get the lay of the land, they message the brain, which in turn sends signals back to the skin. This organ contains color-changing cells such as melanophores, which either expand or contract according to the background the fish is trying to match.

For instance, expanding their cells would make their color darker. All this neurological relaying is “a pretty sophisticated thing to do,” Burgess says—not to mention it takes flatfish between two and eight minutes to blend in.

Even more impressive than how the eyes work is how they get on top of the head in the first place. Flatfishes don’t start out flat. They start out looking like regular fish, kind of diamond shaped, and “as larvae, the eyes are in regular position on each side,” As they develop “the eye begins to migrate, moving over the top of the head, eventually settling on one side or the other”. This also requires the bones in their heads to move.

The flatfish’s bones are pretty pliable at this point, like the soft spot on an infant’s skull, so “as the eye moves, the bones in the head warp in that direction,” An additional bone, found only in flatfish, develops right under the migrating eye, giving them that goofy asymmetrical look.

Pearl oysters are molluscs. Their soft bodies are protected by a tough outer shell, hinged at one side. When a piece of grit becomes embedded in the soft body of the oyster, it protects itself by building up layers of a shiny, shell-like material around the foreign body. This happens naturally, but today many pearls are cultivated in oyster farms, where “seeds” are injected into the oysters so that they will form pearls.

Most jewelry is fashioned out of precious metals and jewels that are found buried in the Earth, but pearls are found inside a living creature, an oyster. Pearls are the result of a biological process -- the oyster's way of protecting itself from foreign substances.

Oysters are not the only type of mollusk that can produce pearls. Clams and mussels can also produce pearls, but that is a much rarer occurrence. Most pearls are produced by oysters in both freshwater and saltwater environments. To understand how pearls are formed in oysters, you must first understand an oyster’s basic anatomy.

Oysters are bivalves, which mean that its shell is made of two parts, or valves. The shell's valves are held together by an elastic ligament. This ligament is positioned where the valves come together, and usually keeps the valves open so the oyster can eat.

As the oyster grows in size, its shell must also grow. The mantle is an organ that produces the oyster's shell, using minerals from the oyster's food. The material created by the mantle is called nacre. Nacre lines the inside of the shell.

­The formation of a natural pearl begins when a foreign substance slips into the oyster between the mantle and the shell, which irritate­s the mantle. It's kind of like the oyster getting a splinter. The oyster's natural reaction is to cover up that irritant to protect itself. The man­tle covers the irritant with layers of the same nacre substance that is used to create the shell. This eventually forms a pearl.

So a pearl is a foreign substance covered with layers of nacre. Most pearls that we see in jewelry stores are nicely rounded objects, which are the most valuable ones. Not all pearls turn out so well. Some pearls form in an uneven shape -- these are called baroque pearls. Pearls, as you've probably noticed, come in a variety of various colors, including white, black, gray, red, blue and green. Most pearls can be found all over the world, but black pearls are indigenous to the South Pacific.

Cultured pearls are created by the same process as natural pearls, but are given a slight nudge by pearl harvesters. To create a cultured pearl, the harvester opens the oyster shell and cuts a small slit in the mantle tissue. Small irritants are then inserted under the mantle. In freshwater cultured pearls, cutting the mantle is enough to induce the nacre secretion that produces a pearl -- an irritant doesn't have to be inserted. While cultured and natural pearls are considered to be of equal quality, cultured pearls are generally less expensive because they aren't as rare.

It is like that life on our planet began in the oceans. As much more of the Earth is covered with water than with land, and the sea can be thousands of metres deep, there is simply more space for living things in the oceans. However, the conditions that they experience there are not so varied, so there are fewer different species than there are on land. Well over 90% of the living things that thrive in the oceans are found in the fairly shallow waters around the continents. However, scientists have found that there is life even in the deepest oceans, although it is not easy to study wildlife in such remote areas.

The deep sea is an extremely harsh environment. It is dark, below 200m the light levels are too low for photosynthesis (the twilight zone), and not a glimmer of sunlight remains beyond 1,000m (the midnight zone). The water is very cold (37-50oF/3-10oC) and consequently has low levels of oxygen. The pressure at a depth of 2.5 miles is about 400 atmospheres, 400 times the pressure on the surface and equivalent to half a tonne per square centimeter. The density of organisms is therefore low. 25% of the estimated 8,700,000 species on earth live in the ocean depths, and 91% of those have yet to be discovered, described and catalogued (CoML). Many of these could potentially hold cures and new treatments for cancer, arthritis and other diseases.

The organisms of the deep sea are truly amazing and extraordinary, with every journey down uncovering more of the mysteries. This month a study published in Proceedings B of the Royal Society described a new species of deep-water acorn worms found 2,700m deep near the Mid-Atlantic Ridge with extremely long "lips" to help them capture prey in a habitat deficient of food.

Living in an environment where food is scarce, organisms need to be able to eat anything and everything that comes their way, the fangtooth (Anoplogaster cornuta) accomplishes this with its large cavernous mouth, and large dagger-like teeth (in fact, the teeth are so large is it difficult to close its mouth).

The deep sea anglerfish (Melanocytes Johnson) is aptly named for its elongated dorsal spine that extends forwards and lures prey towards its wide mouth and sharp teeth, with a glowing lure (containing bioluminescent symbiotic bacteria). The density of organisms in the deep sea is so low, that finding a mate in the right place at the right time can be quite a challenge. To avoid this potential problem, when they do meet, the male anglerfish will bite onto the female, their blood vessels fuse, and he will spend the rest of his life as a sperm producing appendage.

In the mesopelagic (twilight zone) where light levels are low, large eyes and reflective retinas are advantageous to make use of any vestiges of sunlight that penetrate down. Many deep sea fish possess photospheres (light producing organs), these aid in species identification, attracting food, or deterring predators. The lanternfish (small mesopelagic fish of the family Myctophidae) have photophores paired and concentrated in rows on their body and head in species-specific patterns. In some the pattern varies between males and females, with males having concentrations of photophores above the tail, and females below.

The Swimming Green Bomb (Swima bombiviridis) discovered in 2009, armed with "bombs" (shown by the arrow below) that glow a brilliant green when dropped, which they use as a distraction tactic to escape predators.

The Barrel Eye (Macropinna microstoma) is certainly a bizarre looking creature, with two green rotating eyes embedded in their transparent head. The dark "eye" like patches are in fact olfactory organs. Due to the lack of light even further below becomes a less important sense, and in many fish their eyes are considerably reduced, or even degenerate. Watch the video below to see this unique organism in action.

Winning the most awards for “ugliest fish” the Blowfish (Psychrolutes marcidus). This "grumpy", "frowning" "blob" is able to withstand crushing pressure at 1,000m as its body is mostly a gelatinous mass with a density just less than water. It hovers with minimal energy expenditure just above the sea floor waiting for passing food particles.

During the breeding season, walruses gather on the Arctic ice. The males fight each other for the females, often causing serious wounds with their long tusks. But the main reason for these impressive extended teeth is for digging up shellfish from the ocean floor.

The mustached and long-tusked walrus is most often found near the Arctic Circle, lying on the ice with hundreds of companions. These marine mammals are extremely sociable, prone to loudly bellowing and snorting at one another, but are aggressive during mating season. With wrinkled brown and pink hides, walruses are distinguished by their long white tusks, grizzly whiskers, flat flipper, and bodies full of blubber.

Walruses use their iconic long tusks for a variety of reasons, each of which makes their lives in the Arctic a bit easier. They use them to haul their enormous bodies out of frigid waters, thus their “tooth-walking” label, and to break breathing holes into ice from below. Their tusks, which are found on both males and females, can extend to about three feet, and are, in fact, large canine teeth, which grow throughout their lives. Male walruses, or bulls, also employ their tusks aggressively to maintain territory and, during mating season, to protect their harems of females, or cows.

The walrus' other characteristic features are equally useful. As their favorite meals, particularly shellfish, are found near the dark ocean floor, walruses use their extremely sensitive whiskers, called mustacial vibrissae, as detection devices. Their blubbery bodies allow them to live comfortably in the Arctic region—walruses are capable of slowing their heartbeats in order to withstand the polar temperatures of the surrounding waters.

The two subspecies of walrus are divided geographically. Atlantic walruses inhabit coastal areas from northeastern Canada to Greenland, while Pacific walruses inhabit the northern seas off Russia and Alaska, migrating seasonally from their southern range in the Bering Sea—where they are found on the pack ice in winter—to the Chukchi Sea. Female Pacific walruses give birth to calves during the spring migration north.

Penguins are only found in the southern hemisphere, not in the Arctic. Many penguins lay only one egg during the dark days of winter. The female and male penguin’s first bond and then mate to lay an egg the size of a softball on the ice in midwinter. The male thrusts the egg up onto his feet, where it is protected and cushioned by the male’s “brood patch,” a warm fold of feathers and his bulging stomach which rests atop the feet. The egg remains in that place for 9 weeks until it hatches during the coldest months of the Antarctic winter.

Both female and male penguins protect their eggs and newly hatched chicks by enveloping them under a fold of body skin. During the reproductive cycle of the first part the mother penguin has to fast, but after eggs are laid, they go away to fatten them.

The adult males then take over, incubating the eggs and the newly hatched chicks for the 9 weeks in midwinter. The part of the bird’s belly touches the egg and the bare of feathers to facilitate the waft of heat from the father penguin to his offspring. At the end of their babysitting stint, the fathers turn the chicks over to their returning mother penguin and cross the sea again.

If the weather conditions come to be so severe that a parent’s resources can no longer deal with the cold, it abandons the egg to save itself, as it could do under other cases. All penguins are littered with abandoned eggs and dead chicks.

Females lay a single egg in midwinter and then promptly leave it behind. Depending on the volume of the ice, the females might also need to travel some 50 miles to attain the open ocean, in which they will feed on squid, fish, and krill.

In very cold climates, animals need excellent insulation to stop their body heat from escaping. This may be on the outside, in the form of dense hair, fur or feathers, or on the inside, in the form of a thick layer of fat or blubber.

The North Pole and South Pole are covered with snow and ice, the North Pole and South Pole are really cold all the time, we identified polar animals and where they live, learned penguins live at the South Pole and polar bears live at the North Pole.

Polar bears lose so little heat to their environment that they are almost invisible to thermal imaging cameras. But a recent study at the University of Buffalo found that polar bears have also evolved genes that produce more nitric oxide than other bear species. Nitric oxide is a signalling molecule and one of the mechanisms it controls is whether cells use their available nutrients to produce metabolic energy, or simply convert it into body heat. Polar bears seem to be able to divert more of their body’s resources into generating heat. This relies on them getting enough fuel for this process and adult polar bears have a high calorie diet; they mostly eat seal blubber.

Polar bears are found in very cold parts of the world where temperatures can drop as low as -20° Fahrenheit (-29° Celsius). Without proper protection, this weather can be deadly, so polar bears stay warm by utilizing their thick fur and fat, or blubber. Polar bears have evolved along with other Arctic animals to take advantage of minimal warmth, and can sometimes actually become too warm because their bodies are so efficient at trapping heat.

A polar bear's fur is the first step in keeping warm. Polar bears actually have two types of fur: long oily guard hairs and short insulating hairs. Polar bears stay warm by combining the properties of these two hairs. The guard hairs are actually hollow, and look like very small tubes of glass. The hollow guard hairs trap warmth and bring it close to the skin while also providing an oily outer layer that prevents the polar bear from getting wet. The insulating hairs trap heat close to the skin, much like insulating underwear on humans.

As in other extreme climates, only specially adapted plants and animals can live in the coldest parts of the world. In fact, at the North and South Poles, almost nothing can survive, but around the edges of the Arctic and Antarctic there are seas rich in plant and animal life. This means that larger animals, living on the edge of the ice, can find food in the teeming waters.

Air temperatures averaging below freezing over the year (usually well below freezing) with a range in many places around -40°C to +10°C (-40°F to +50°F) and highs (very briefly and rarely) up to +22°C (+72°F) amongst rocks and moss banks. Much of Antarctica is a cold largely featureless icy desert where above freezing temperatures are hardly reached if ever at all. The temperature of the Antarctic Ocean that surrounds the continent varies from -2°C to +2°C (+28.4°F to +35.6°F) over the year. Seawater freezes at -2°C (+28.4°F) so it can't get any colder and still be water.

Arctic and Antarctic birds and mammals such as penguins, whales, bears, foxes  and seals - are warm blooded animals and they maintain similar internal body temperatures to warm blooded animals in any other climate zone - that is 35-42°C (95-107°F) depending on the species. They have to keep high body temperatures to remain active. These animals are known as endotherms (endo-inside + therm-heat) as they generate their heat internally. The Polar Regions' cold and wind mean that this heat can very quickly be lost leading to hypothermia (hypo-under).

Many (non-polar) animals are ectotherms (ecto-outside) , which means that they generate so little heat internally they are dependent on the external environment to warm them up to a level where their body and enzymes function sufficiently well enough for an active and functional life. Typically they raise their temperature by basking in the sun until they are warm enough to become active. Reptiles and amphibians do this while invertebrates are usually small enough to be able to warm up quickly to the ambient temperature from the air alone without basking in direct sunlight.

A large ectothermic Arctic or Antarctic land animal would never get enough energy regularly enough from the surroundings to become sufficiently active once it had cooled. All polar land animals of any size therefore need to be warm-blooded to be active. The environment is so extreme that the size limit in Antarctica for an ectotherm is about 13mm, the size of the largest fully terrestrial (land) animal in Antarctica. In other words any animal larger than this would be unlikely to be able to warm up enough to become active before it started to get cold again.

At the North and South Poles there are areas that are covered by thick layers of snow and ice all year round, but the two areas are very different. The Antarctic region, around the South Pole, has land far under the ice. The Arctic region, around the North Pole, is actually frozen sea. It is possible for a submarine to travel right under the North Pole. Because in Polar Regions the sea is warmer than the land or ice, the Arctic, with more sea, is not as cold as the Antarctic.

Antarctica, or the South Pole region, is a continent which is covered with an immense ice shelf. The Arctic region, however, is mainly located in the north polar ocean and includes several larger islands such as Greenland, Spitzbergen, Franz Josef Land, Severnaya Zemlya Wrangel Island, Bank Island, Victoria Island, Ellesmere Island and various others that all boarder countries like Russia, Canada, Alaska and Greenland. The north polar ocean is covered by year round ice caps that generally extend far south during the Arctic winter and are made up of around 16 million square kilometers of ice. Polar bears live solely in the Arctic areas, while penguins on the other hand, are found in the southern Antarctic regions. For that reason polar bears and penguins never cross paths.

Unlike Antarctica, the Arctic is not a continent which is the predominant different between the two polar regions. Under the massive ice cap of the Arctic lies the Arctic Ocean whose depths reach 15,000 feet below the surface. Often times the two polar regions are confused due to their having such similar names. The Arctic was discovered by Phoenician sailors years before the common era (CE). They named the newly discovered region after a polar star which guided them to the end of the earth. The star was called “Arktos” by the Greeks during this time which meant “land of the big bear”. Coincidentally, this title helps many people remember that polar bears are found in the Arctic rather than Antarctica. Also found in the Arctic region is the arctic fox, different species of seals and whales, puffins, fulmars, and other bird species.

Though the Arctic is obviously a very cold region, it is still much warmer than Antarctica in the South. Known as “the land of the midnight sun,” the Arctic is located in a landmass above 12 frozen feet of ice.

1. Penguins are only seen in Antarctica. There are no penguins in the Arctic. In the Antarctic, there are no land predators which also mean it’s a bit easier for penguins to survive. The waters, however, are a different story!

2. Polar bears only exist in the Arctic. These larger-than-life bears roam the North in search of prey and habitat.

3. Arguably the biggest difference between the two regions is that Antarctica is a continent surrounded by oceans, while the Arctic is an ocean surrounded by continents and countries —north America, Europe, and Asia.

4. Because they are on opposite sides of the world, the Arctic and the Antarctic do not share the same seasons. The Arctic enjoys winter from October through March, while Antarctica’s winter is from March through September.

5. The Arctic has a considerable flora— with some 900 flowering plants. The Antarctic has very little vegetation, mostly lichens and algae. There are only two flowering plans in Antarctica.

There are seasonal variations at the Poles, but these are much more noticeable in the Arctic than in the Antarctic. During the Arctic summer the sea ice begins to melt and break away in large icebergs. Although the area around the North Pole is always covered by ice, the snow melts around the edges of the Arctic Circle so that Arctic animals can browse on the sparse vegetation. One result of this is that some Arctic mammals, which need camouflage to keep them safe from predators, change the colour of their coats from white in the winter to brown in the summer months.

The Arctic region contains a wide range of landscapes; plains, mountains, some very large significant rivers and lakes, rolling hills, huge stretches of tundra and the edge of the largest biome in the world, the taiga. The ice in the Arctic Ocean is largely formed from the frozen sea and contained by the surrounding land masses. It contains a large proportion of multiyear sea-ice that is 3-4m (10-13 feet) thick with some much thicker ridges. Greenland has the largest ice cap in the Arctic (and second largest in the world after the Antarctic ice cap) other than this permanent ice is quite rare and relatively small in extent. Ice bergs form when the edges of the Greenland ice sheet reach the sea, most of the ice in the Arctic even in the summer is frozen sea ice.

The ice you are standing on is 1m to 3m (3-10ft) thick floating on the Arctic Ocean, it is made of frozen sea water with some snow on top, sea level is usually no more than 1m below your feet and the sea bed another 4,260m below that. The ice may be flat and smooth or rough, having been broken up and refrozen together again. The ice is moving at anywhere from a snails' pace to walking pace. You are about 730km from the nearest land at the northern tip of Greenland. Temperatures here are estimated from those measured elsewhere in the Arctic, as there are no structures or a settlement out on the ocean, the ice is too unreliable and unstable.

Antarctica is 98% covered in ice which means that away from coastal regions (and even including many coastal regions) the landscape is icy mountains, glaciers or smooth ice-sheet. There are no significant rivers and none that flow year round, lakes are small, rare and often permanently frozen over, there is very little land vegetation, and no grassland, shrubs or trees. There are small areas of tundra on the Antarctic Peninsula and larger expanses on a number of Antarctic and sub Antarctic islands (though nothing like the huge areas found in the Arctic).

The total surface area of Antarctica approximately doubles each winter as sea-ice forms around the coasts, in the summer this ice breaks up and drifts north mainly melting as it does so, Antarctic sea-ice is therefore mainly first year ice. The great ice sheets of Antarctica calve enormous ice bergs into the sea that are measured in square miles (sometimes hundreds or thousands of them), much of the ice in Antarctic waters especially in the summer is freshwater ice from glaciers and ice sheets.

The South Pole has the opposite to this with the sun at its highest around the 21st of December, midsummer to the North Poles midwinter. You are standing at an altitude of about 2,835m (9,300ft) on ice that is 2,700m (9,000ft) thick, it reaches down to rock which rises to just over 100m above sea level, this rock is pushed into the earth's mantle by the weight of the ice. Altitude sickness is a risk at the South Pole for new arrivals arriving by plane. The ice is made from accumulated snowfall that has built up because it never melts. The ice is moving towards the Weddell Sea in the west at about 10m (33ft) per year. You are about 1,300km from the nearest sea at the Bay of Whales. Temperatures have been measured at the South Pole since 1956 as there is a large research station there.

          The great apes are the nearest living relatives to Homo sapiens. There are four species of great ape: the orang-utan, chimpanzee, gorilla and gibbon. Both orang-utans and gibbons spend most of their time in the trees, where they are very agile, swinging from branch to branch. Gorillas live in family groups, led by a large male, and feed mainly on the ground. The dominant male is often called a “silverback” — like humans, their hair becomes grey with age. Chimpanzees are very intelligent. They can use tools and solve puzzles. Their gestures and expressions often make them seem uncannily like humans.

          Chimpanzees now have to share the distinction of being our closest living relative in the animal kingdom. An international team of researchers has sequenced the genome of the bonobo for the first time, confirming that it shares the same percentage of its DNA with us as chimps do. The team also found some small but tantalizing differences in the genomes of the three species—differences that may explain how bonobos and chimpanzees don't look or act like us even though we share about 99% of our DNA.

          "We're so closely related genetically, yet our behavior is so different," says team member and computational biologist Janet Kelso of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. "This will allow us to look for the genetic basis of what makes modern humans different from both bonobos and chimpanzees."

          Ever since researchers sequenced the genome in 2005, they have known that humans share about 99% of our DNA with chimpanzees, making them our closest living relatives. But there are actually two species of apes that are this closely related to humans: bonobos and the common chimpanzee. This has prompted researchers to speculate whether the ancestor of humans, chimpanzees, and bonobos looked and acted more like a bonobo, a chimpanzee, or something else—and how all three species have evolved differently since the ancestor of humans split with the common ancestor of bonobos and chimps between 4 million and 7 million years ago in Africa.

          The international sequencing effort led from Max Planck chose a bonobo named Ulindi from the Leipzig Zoo as its subject, partly because she was a female (the chimp genome was of a male). The analysis of Ulindi's complete genome, reported online today in Nature, reveals that bonobos and chimpanzees share 99.6% of their DNA. This confirms that these two species of African apes are still highly similar to each other genetically, even though their populations split apart in Africa about 1 million years ago, perhaps after the Congo River formed and divided an ancestral population into two groups. Today, bonobos are found in only the Democratic Republic of Congo and there is no evidence that they have interbred with chimpanzees in equatorial Africa since they diverged, perhaps because the Congo River acted as a barrier to prevent the groups from mixing. The researchers also found that bonobos share about 98.7% of their DNA with humans—about the same amount that chimps share with us.

          When the Max Planck scientists compared the bonobo genome directly with that of chimps and humans, however, they found that a small bit of our DNA, about 1.6%, is shared with only the bonobo, but not chimpanzees. And we share about the same amount of our DNA with only chimps, but not bonobos. These differences suggest that the ancestral population of apes that gave rise to humans, chimps, and bonobos was quite large and diverse genetically—numbering about 27,000 breeding individuals. Once the ancestors of humans split from the ancestor of bonobos and chimps more than 4 million years ago, the common ancestor of bonobos and chimps retained this diversity until their population completely split into two groups 1 million years ago. The groups that evolved into bonobos, chimps, and humans all retained slightly different subsets of this ancestral population's diverse gene pool—and those differences now offer clues today to the size and range of diversity in that ancestral group.

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          Primates other than humans communicate with each other in a number of ways. Many primates use touch to establish relationships, grooming each other to show friendship and to remove insects. Howler monkeys, living in the tropical forests of South America, make very loud calls. The male calls to mark his territory and can often be heard over 3km (almost 2 miles) away. Male gibbons, too, have loud calls, used for communicating with family members and to warn off other males. Some Old World monkeys have brightly coloured faces and bottoms, which the males use in courting displays and to frighten off enemies and rivals. Gorillas thump on the ground to warn off rival males, or beat their chests and roar to demonstrate their strength and power. Chimpanzees communicate with each other by using sounds and gestures.

          Like other animals, primates communicate to satisfy their biological and social needs, such as avoiding predators, interacting with other group members, or maintaining cohesion during travel. To this end, they use a range of different signals, many of which have directly evolved as ritualised abbreviations of more basic behavioural or physiological processes. For example, chimpanzees sometimes react with pilo-erection (bristling of hair) during conflicts, which makes them appear bigger and more dangerous and conveys their willingness to escalate. Communication signals have thus evolved partly to be psychologically effective on receivers (Guilford & Dawkins 1991).

          Most primates live in groups in which members know each other individually and maintain multifaceted social relations; factors which are thought to favour the evolution of advanced communication skills. However, other animals with complex social behaviour, such as dolphins, also show sophisticated communication skills, suggesting that complex communication is not limited to primates.

          Monkeys sometimes produce terrestrial predator alarms when competing over food, even though no predator is around. As a result, other group members run to safety, which then gives the caller a foraging advantage. In general, however, primates rarely produce such dishonest signals, or ‘cry wolf'. Why is dishonest signalling not more common? One solution has been given by Zahavi's ‘handicap principle', which states that receivers will only attend to signals that are difficult to fake by low-quality or poorly motivated individuals. It has also been argued that, in primates, individuals know and need each other and thus gain little from deception. Moreover, primates can learn to ignore unreliable signallers, suggesting that ‘reputation' acts as a further safeguard against dishonest signalling. Honest signalling prevails because of sceptical receivers.

          Primate communication takes place in all major modalities. Olfaction is one of the least researched modalities, partly because it is difficult to measure and manipulate olfactory cues, especially in the wild. Nevertheless, probably all primates secrete scents that influence others. An interesting human example is women apparently influencing each other's ovulation through odourless cues. Another remarkable example is the ‘stink fights' of male ring-tailed lemurs. During conflicts, males rub their tails across their wrist and chest glands before waving them at each other. Generally, olfactory cues play important roles in stating claims over resources and displaying individual characteristics, such as reproductive state, social rank, immune-compatibility, and other genetic traits. One difficulty with research on olfactory communication is that it is often unclear whether scent-bearing substances are actively and strategically released into the environment, or whether they are mere by-products of general metabolic processes. Active scent marking and self-anointment (applying scent-bearing substances onto a substrate or body) are notable exceptions, but in many cases it is unclear whether olfactory cues qualify as proper communication signals.

          In the visual domain, primates use a range of facial displays and body part movements as communication signals, sometimes combined with tactile components. Gorilla chest beating and Rhesus monkeys bared-teeth displays are examples of how different species express social rank with visual signals. Current research has focused much on gestures, which are interesting because of their partly flexible, partly species-specific use in a variety of social contexts. Gestures have been studied mainly in great apes, where considerable variation between individuals and groups has been found. Whether some of this variation is socially learned and thus potentially ‘cultural' is still an unresolved question. A more established finding is that, during gesturing, apes take into account each other's attention and deploy their signals accordingly. Interestingly, however, there is almost no evidence that primate gesture, or combinations thereof, carry symbolic meaning by referring to external entities. Instead, they appear to function primarily to facilitate ongoing social interactions, to bond with others, or to persuade others to behave in a desired way.

          For many primates, vocalizations are the main channel of communication. Vocal repertoires tend to be species-specific, indicating that they develop under strong genetic control. Humans also possess a specific repertoire of such context-specific calls but, in addition, they also possess extensive control over vocal production, an ability that develops early and is crucial for the acquisition of speech. Such high degree of vocal control is not seen in other primates and one interesting hypothesis is that it is the product of relatively recent genetic changes during human evolution. If this is correct then our hominid ancestors must have relied on a primate-like communication system.

          In sum, primates communicate using all major modalities. Olfactory communication is poorly researched but is probably widespread, mostly inflexible and contextually confined to basic biological functions. Within the visual modality, gestures are somewhat of an exception because of their flexibility and socially targeted use. Finally, vocal communication is based on species-specific repertoires, with some flexibility in use but little in structure.

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          The monkeys of the American continent, the “New” World, differ in several ways from those of Africa and Asia. New World monkeys, such as capuchins, spider monkeys, howler monkeys and woolly monkeys have flat noses and widely spaced eyes. They live in family groups and spend much of their time in the trees, feeding mainly on fruit and leaves. Most of them have long tails, which they can use like an extra arm or leg to cling to branches. Old World monkeys live in a wide variety of habitats. They walk on all fours and, although they may sleep in trees, some species live mainly on the ground. They have narrow noses, and their nostrils face forward. Old World monkeys include macaques, mandrills and mangabeys.

          To many, the word monkey means just one thing—some vine-swinging, tree-dwelling primate, usually brown and fuzzy and cute. But did you know that there are actually over 250 different species of monkeys? These species are divided into two main groups—Old World and New World monkeys. The term “old world” refers to the areas (Europe, Africa, and Asia) known to the Europeans prior to the discovery of the “new world” (the Americas). Old World monkeys are native to Africa and Asia while New World monkeys are indigenous to the Americas, but their homes are not the only ways in which they are different.

          New World monkeys are members of five different primate families (Callitrichidae, Cebidae, Aotidae, Pitheciidae, and Atelidae) and consist of almost exclusively arboreal (tree-dwelling) species like marmosets, tamarins, capuchins, and spider monkeys. Old World monkeys belong to the family Cercopithecidae and consist of species such as macaques, baboons, and vervet monkeys. These monkeys spend much more of their time on the ground, but can be found in habitats ranging from the rainforest to the savannah to the mountains!

          One of the biggest differences between these two groups of monkeys is their tails. On one hand, some species of New World monkeys possess prehensile tails, meaning they can use their tails to grasp or hold on to objects. Their tails can aid these monkeys in finding and eating food in the canopy as well as moving amongst the trees, as their tails provide extra support and balance. On the other hand, Old World monkeys all have tails, but they lack the ability to grasp objects. However, some Old World monkeys have pads called ischial callosities surrounding their hind region. As these monkeys tend to spend more time on the ground than their arboreal New World counterparts, these calloused areas of skin provide support when they sit to feed or rest.

          These two monkey groups also differ in a few other anatomical ways. New World monkeys have an additional premolar tooth in their mouths; they have three while Old World monkeys only have two. Old World monkeys have fingernails and toenails, while New World monkeys often have claws on all of their digits with the exception of the big toes of marmosets and tamarins. Another exception is the spider and howler monkeys— New World species with nails like Old World monkeys. Old World monkey thumbs are also more opposable and similar to our own. New World monkeys are also flat-nosed (platyrrhine) with nostrils further apart, while Old World monkeys have nostrils closer together and a nose which faces down (catarrhine).

          Another difference between these monkeys is the way they care for their young. In New World monkeys, it is common for the males to be involved in infant care. However, this is extremely rare in Old World monkeys; instead, the job belongs entirely to the females. Old World mothers also often carry their babies on their bellies, while New World babies will more commonly ride on their mothers’ backs.

          Finally, these two groups of monkeys differ in the foods that make up the bulk of their diet. New World monkeys generally rely much more on fruit than Old World monkeys which instead focus more on leaves and grasses. Some even have specialized stomachs that can better break down the cellulose found in plants.

          As you can see, even though these animals all share the title of “monkey,” they are more different than you might realize! Every species is unique and important in its own way.

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          There are about 180 different species of primate, most of them living in the tropical regions of the world. The exception, and also the most numerous primate, is Homo sapiens — human beings. All primates have fairly large brains and forward-facing eyes that enable them to judge distances accurately. Instead of claws or hoofs, like other mammals, they have fingers and toes with soft, sensitive tips. They also have the ability to grasp with their fingers, thumbs and toes. The order of primates can be divided into prosimians, also known as primitive primates , and anthropoids, the higher primates, which include marmosets, monkeys, apes and, of course, human beings.

          A “primate” refers to any member of the biological order Primates and contains species that are commonly related such as monkeys, lemurs, bush babies and apes. Humans belong to the category of apes. Primates are found in all continents around the world, with non-human primates mostly occurring in Africa, Central and South America and southern Asia. The order of primates is divided into three main groups namely: prosimians, monkeys of the New World, and monkeys and apes of the Old World. The distinguishing characteristic of primates includes five fingers (pentadactyly), a dental pattern and an unspecialized body plan. Additionally, most primates have fingernails and opposing thumbs. Old World monkeys and New World monkeys live in tropical forest environments of Asia, Africa, and the Americas. Primates are social animals who live in bands and small groups. Some of the largest primates include gorillas, orangutans, baboons, and chimpanzees.

          As per the best estimates, these are some of the most populous primates on Earth. Humans are the most populous primates on earth with a population of about 7.5 billion people. The modern human, Homo sapiens, is the only extant member of Hominine tribe (human tribe) and belongs to the family of great apes. Humans have larger and more complex brains compared with other apes. The success of the modern human species is attributed to the large and complex brain and the development of special cognitive abilities which enable the human to reason, use language, solve problems and live in social and cultural units. Our existence as humans has been sustained through hunting and gathering in ancient band societies. Today, humans are the most dominant of species on earth and the most influential, affecting greatly the habitats and environments of other species.

          The Muller's Bornean Gibbon is the second most populous primate species on earth. They live in the evergreen tropical forest and mainly found in Borneo. They are native to Indonesia and Malaysia. Over the last 45 years, the Bornean gibbon has witnessed a 50% reduction in population due to deforestation, hunting, and poaching. They thrive well in evergreen forests where they can be found in large numbers.

          Also known as the bleeding-heart monkey, they belong to the old world monkey group and are found in the highlands of Ethiopia, where they occur in large populations around the Semien mountains. Geladas are the most terrestrial primates in the world (aside from humans). They are mostly grass-eaters and represent the once numerous species of grass-eater primates. They stay in high altitude regions of the mountain. As a result, they have developed short stumpy fingers which make them adept rock climbers.

          The Common chimpanzee is also known as the robust chimpanzee and is a species of the great ape. It is characterized by coarse black hair, bare face, fingers, and feet. They live in groups of 15-150 individuals. They use tools such as modifying sticks and rocks to forage and hunt for food. Today, their population is estimated to be between 172,700 - 299,700 individuals. They face threats due to habitat loss, poaching, and disease.

          Gorillas are the largest of the living apes and primates. They are mainly found in the subtropical forests of central Africa. There are three main groupings of gorillas; eastern, western and mountain gorillas of Africa. The western gorilla is smaller in size and lighter than their eastern relative. Mature males are known as silverbacks due to the silvery-white hair on their back. They live in sociable groups led by a dominant male and several females and their offspring. The male weighs up to 140kg while the female weighs 70kg.