The giant squid (genus: Architeuthis) is a deep-ocean dwelling squid in the family Architeuthidae, represented by as many as eight species. Giant squid can grow to a tremendous size: recent estimates put the maximum size at 13 metres (43 ft) for females and 10 metres (33 ft) for males from caudal fin to the tip of the two long tentacles (second only to the colossal squid at an estimated 14 metres (46 ft), one of the largest living organisms). The mantle is about 2 metres (6.6 ft) long (more for females, less for males), and the length of the squid excluding its tentacles is about 5 metres (16 ft). There have been claims reported of specimens of up to 20 metres (66 ft), but no animals of such size have been scientifically documented.
On September 30, 2004, researchers from the National Science Museum of Japan and the Ogasawara Whale Watching Association took the first images of a live giant squid in its natural habitat. Several of the 556 photographs were released a year later. The same team successfully filmed a live giant squid for the first time on December 4, 2006.
ANATOMY
Like all squid, a giant squid has a mantle (torso), eight arms, and two longer tentacles (the longest known tentacles of any squid species). The arms and tentacles account for much of the squid's great length, so giant squid are much lighter than their chief predators, sperm whales. Scientifically documented specimens have weighed hundreds, rather than thousands, of kilograms.
The inside surfaces of the arms and tentacles are lined with hundreds of sub-spherical suction cups, 2 to 5 centimetres (0.79 to 2.0 in) in diameter, each mounted on a stalk. The circumference of these suckers is lined with sharp, finely serrated rings of chitin. The perforation of these teeth and the suction of the cups serve to attach the squid to its prey. It is common to find circular scars from the suckers on or close to the head of sperm whales that have attacked giant squid. Each arm and tentacle is divided into three regions — carpus ("wrist"), manus ("hand") and dactylus ("finger"). The carpus has a dense cluster of cups, in six or seven irregular, transverse rows. The manus is broader, close to the end of the arm, and has enlarged suckers in two medial rows. The dactylus is the tip. The bases of all the arms and tentacles are arranged in a circle surrounding the animal's single parrot-like beak, as in other cephalopods.
Giant squid have small fins at the rear of the mantle used for locomotion. Like other cephalopods, giant squid are propelled by jet — by pushing water through its mantle cavity through the funnel, in gentle, rhythmic pulses. They can also move quickly by expanding the cavity to fill it with water, then contracting muscles to jet water through the funnel. Giant squid breathe using two large gills inside the mantle cavity. The circulatory system is closed, which is a distinct characteristic of cephalopods. Like other squid, they contain dark ink used to deter predators.
Giant squid have a sophisticated nervous system and complex brain, attracting great interest from scientists. They also have the largest eyes of any living creature except perhaps colossal squid — over 30 centimetres (1 ft) in diameter. Large eyes can better detect light (including bioluminescent light), which is scarce in deep water.
Giant squid and some other large squid species maintain neutral buoyancy in seawater through an ammonium chloride solution which flows throughout their body and is lighter than seawater. This differs from the method of floatation used by fish, which involves a gas-filled swim bladder. The solution tastes somewhat like salmiakki and makes giant squid unattractive for general human consumption.
Like all cephalopods, giant squid have organs called statocysts to sense their orientation and motion in water. The age of a giant squid can be determined by "growth rings" in the statocyst's "statolith", similar to determining the age of a tree by counting its rings. Much of what is known about giant squid age is based on estimates of the growth rings and from undigested beaks found in the stomachs of sperm whales.
SIZE
The giant squid is the second largest mollusc and the second largest of all extant invertebrates. It is only exceeded in size by the Colossal Squid, Mesonychoteuthis hamiltoni, which may have a mantle nearly twice as long. Several extinct cephalopods, such as the Cretaceous vampyromorphid Tusoteuthis and the Ordovician nautiloid Cameroceras may have grown even larger.
Yet, giant squid size, particularly total length, has often been misreported and exaggerated. Reports of specimens reaching and even exceeding 20 metres (66 ft) in length are widespread, but no animals approaching this size have been scientifically documented. According to giant squid expert Dr. Steve O'Shea, such lengths were likely achieved by greatly stretching the two tentacles like elastic bands.
Based on the examination of 130 specimens and of beaks found inside sperm whales, giant squid's mantles are not known to exceed 2.25 metres (7.4 ft) in length. Including the head and arms, but excluding the tentacles, the length very rarely exceeds 5 metres (16 ft). Maximum total length, when measured relaxed post mortem, is estimated at 13 metres (43 ft) for females and 10 metres (33 ft) for males from caudal fin to the tip of the two long tentacles. Giant squid exhibit reverse sexual dimorphism. Maximum weight is estimated at 275 kilograms (610 lb) for females and 150 kilograms (330 lb) for males
Tuesday, January 13, 2009
Water, the Essence of Life
Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71% of the Earth's surface. On Earth, it is found mostly in oceans and other large water bodies, with 1.6% of water below ground in aquifers and 0.001% in the air as vapor, clouds (formed of solid and liquid water particles suspended in air), and precipitation.Saltwater oceans hold 97% of surface water, glaciers and polar ice caps 2.4%, and other land surface water such as rivers, lakes and ponds 0.6%. A very small amount of the Earth's water is contained within biological bodies and manufactured products. Other water is trapped in ice caps, glaciers, aquifers, or in lakes, sometimes providing fresh water for life on land.
Water moves continually through a cycle of evaporation or transpiration (evapotranspiration), precipitation, and runoff, usually reaching the sea. Winds carry water vapor over land at the same rate as runoff into the sea, about 36 Tt (1012kilograms) per year. Over land, evaporation and transpiration contribute another 71 Tt per year to the precipitation of 107 Tt per year over land. Clean, fresh drinking water is essential to human and other life. Access to safe drinking water has improved steadily over the last decades in almost every part of the world.[1] However, some observers have estimated that by 2025 more than half of the world population will be facing water-based vulnerability, a situation which has been called a water crisis by the United Nations. Water plays an important role in the world economy, as it functions as a solvent for a wide variety of chemical substances and facilitates industrial cooling and transportation. Approximately 70 percent of freshwater is consumed by agriculture.
CHEMICAL AND PHYSICAL PROPERTIES
Water is the chemical substance with chemical formula H2O: one molecule of water has two hydrogen atoms covalently bonded to a single oxygen atom.
The major chemical and physical properties of water are:
Water is a tasteless, odorless liquid at ambient temperature and pressure. The color of water and ice is, intrinsically, a very light blue hue, although water appears colorless in small quantities. Ice also appears colorless, and water vapor is essentially invisible as a gas.
Water is transparent, and thus aquatic plants can live within the water because sunlight can reach them. Only strong UV light is slightly absorbed.
Since oxygen has a higher electronegativity than hydrogen, water is a polar molecule. The oxygen has a slight negative charge while the hydrogens have a slight positive charge giving the article a strong effective dipole moment. The interactions between the different dipoles of each molecule cause a net attraction force associated with water's high amount of surface tension.
Another very important force that causes the water molecules to stick to one another is the hydrogen bond.
The boiling point of water (and all other liquids) is directly related to the barometric pressure. For example, on the top of Mt. Everest water boils at about 68 °C (154 °F), compared to 100 °C (212 °F) at sea level. Conversely, water deep in the ocean near geothermal vents can reach temperatures of hundreds of degrees and remain liquid.
Water has a high surface tension caused by the weak interactions, (Van Der Waals Force) between water molecules because it is polar. The apparent elasticity caused by surface tension drives the capillary waves.
Water also has high adhesion properties because of its polar nature.
Capillary action refers to the tendency of water to move up a narrow tube against the force of gravity. This property is relied upon by all vascular plants, such as trees.
Water is a very strong solvent, referred to as the universal solvent, dissolving many types of substances. Substances that will mix well and dissolve in water, e.g. salts, sugars, acids, alkalis, and some gases: especially oxygen, carbon dioxide (carbonation), are known as "hydrophilic" (water-loving) substances, while those that do not mix well with water (e.g. fats and oils), are known as "hydrophobic" (water-fearing) substances.
All the major components in cells (proteins, DNA and polysaccharides) are also dissolved in water.
Pure water has a low electrical conductivity, but this increases significantly upon solvation of a small amount of ionic material such as sodium chloride.
Water has the second highest specific heat capacity of any known chemical compound, after ammonia, as well as a high heat of vaporization (40.65 kJ mol−1), both of which are a result of the extensive hydrogen bonding between its molecules. These two unusual properties allow water to moderate Earth's climate by buffering large fluctuations in temperature.
The maximum density of water is at 3.98 °C (39.16 °F). Water becomes even less dense upon freezing, expanding 9%. This causes an unusual phenomenon: ice floats upon water, and so water organisms can live inside a partly frozen pond because the water on the bottom has a temperature of around 4 °C (39 °F).
Water is miscible with many liquids, for example ethanol, in all proportions, forming a single homogeneous liquid. On the other hand, water and most oils are immiscible usually forming layers according to increasing density from the top. As a gas, water vapor is completely miscible with air.
Water forms an azeotrope with many other solvents.
Water can be split by electrolysis into hydrogen and oxygen.
As an oxide of hydrogen, water is formed when hydrogen or hydrogen-containing compounds burn or react with oxygen or oxygen-containing compounds. Water is not a fuel, it is an end-product of the combustion of hydrogen. The energy required to split water into hydrogen and oxygen by electrolysis or any other means is greater than the energy released when the hydrogen and oxygen recombine.
Elements which are more electropositive than hydrogen such as lithium, sodium, calcium, potassium and caesium displace hydrogen from water, forming hydroxides. Being a flammable gas, the hydrogen given off is dangerous and the reaction of water with the more electropositive of these elements is violently explosive.
WATER ON EARTH
Hydrology is the study of the movement, distribution, and quality of water throughout the Earth. The study of the distribution of water is hydrography. The study of the distribution and movement of groundwater is hydrogeology, of glaciers is glaciology, of inland waters is limnology and distribution of oceans is oceanography. Ecological processes with hydrology are in focus of ecohydrology.
The collective mass of water found on, under, and over the surface of a planet is called hydrosphere. Earth's approximate water volume (the total water supply of the world) is 1 360 000 000 km³ (326 000 000 mi³). Of this volume:
1 320 000 000 km³ (316 900 000 mi³ or 97.2%) is in the oceans.
25 000 000 km³ (6 000 000 mi³ or 1.8%) is in glaciers, ice caps and ice sheets.
13 000 000 km³ (3,000,000 mi³ or 0.9%) is groundwater.
250 000 km³ (60,000 mi³ or 0.02%) is fresh water in lakes, inland seas, and rivers.
13 000 km³ (3,100 mi³ or 0.001%) is atmospheric water vapor at any given time.
Groundwater and fresh water are useful or potentially useful to humans as water resources.
Liquid water is found in bodies of water, such as an ocean, sea, lake, river, stream, canal, pond, or puddle. The majority of water on Earth is sea water. Water is also present in the atmosphere in solid, liquid, and vapor states. It also exists as groundwater in aquifers.
The most important geological processes caused by water are: chemical weathering, water erosion, water sediment transport and sedimentation, mudflows, ice erosion and sedimentation by glacier
EFFECTS ON LIFE
From a biological standpoint, water has many distinct properties that are critical for the proliferation of life that set it apart from other substances. It carries out this role by allowing organic compounds to react in ways that ultimately allow replication. All known forms of life depend on water. Water is vital both as a solvent in which many of the body's solutes dissolve and as an essential part of many metabolic processes within the body. Metabolism is the sum total of anabolism and catabolism. In anabolism, water is removed from molecules (through energy requiring enzymatic chemical reactions) in order to grow larger molecules (e.g. starches, triglycerides and proteins for storage of fuels and information). In catabolism, water is used to break bonds in order to generate smaller molecules (e.g. glucose, fatty acids and amino acids to be used for fuels for energy use or other purposes). Water is thus essential and central to these metabolic processes. Therefore, without water, these metabolic processes would cease to exist, leaving us to muse about what processes would be in its place, such as gas absorption, dust collection, etc.
Water is also central to photosynthesis and respiration. Photosynthetic cells use the sun's energy to split off water's hydrogen from oxygen. Hydrogen is combined with CO2 (absorbed from air or water) to form glucose and release oxygen. All living cells use such fuels and oxidize the hydrogen and carbon to capture the sun's energy and reform water and CO2 in the process (cellular respiration).
Water is also central to acid-base neutrality and enzyme function. An acid, a hydrogen ion (H+, that is, a proton) donor, can be neutralized by a base, a proton acceptor such as hydroxide ion (OH−) to form water. Water is considered to be neutral, with a pH (the negative log of the hydrogen ion concentration) of 7. Acids have pH values less than 7 while bases have values greater than 7. Stomach acid (HCl) is useful to digestion. However, its corrosive effect on the esophagus during reflux can temporarily be neutralized by ingestion of a base such as aluminum hydroxide to produce the neutral molecules water and the salt aluminum chloride. Human biochemistry that involves enzymes usually performs optimally around a biologically neutral pH of 7.4.
For example a cell of Escherichia coli contains 70% of water, a human body 60–70%, plant body up to 90% and the body of an adult jellyfish is made up of 94–98% water.
Water moves continually through a cycle of evaporation or transpiration (evapotranspiration), precipitation, and runoff, usually reaching the sea. Winds carry water vapor over land at the same rate as runoff into the sea, about 36 Tt (1012kilograms) per year. Over land, evaporation and transpiration contribute another 71 Tt per year to the precipitation of 107 Tt per year over land. Clean, fresh drinking water is essential to human and other life. Access to safe drinking water has improved steadily over the last decades in almost every part of the world.[1] However, some observers have estimated that by 2025 more than half of the world population will be facing water-based vulnerability, a situation which has been called a water crisis by the United Nations. Water plays an important role in the world economy, as it functions as a solvent for a wide variety of chemical substances and facilitates industrial cooling and transportation. Approximately 70 percent of freshwater is consumed by agriculture.
CHEMICAL AND PHYSICAL PROPERTIES
Water is the chemical substance with chemical formula H2O: one molecule of water has two hydrogen atoms covalently bonded to a single oxygen atom.
The major chemical and physical properties of water are:
Water is a tasteless, odorless liquid at ambient temperature and pressure. The color of water and ice is, intrinsically, a very light blue hue, although water appears colorless in small quantities. Ice also appears colorless, and water vapor is essentially invisible as a gas.
Water is transparent, and thus aquatic plants can live within the water because sunlight can reach them. Only strong UV light is slightly absorbed.
Since oxygen has a higher electronegativity than hydrogen, water is a polar molecule. The oxygen has a slight negative charge while the hydrogens have a slight positive charge giving the article a strong effective dipole moment. The interactions between the different dipoles of each molecule cause a net attraction force associated with water's high amount of surface tension.
Another very important force that causes the water molecules to stick to one another is the hydrogen bond.
The boiling point of water (and all other liquids) is directly related to the barometric pressure. For example, on the top of Mt. Everest water boils at about 68 °C (154 °F), compared to 100 °C (212 °F) at sea level. Conversely, water deep in the ocean near geothermal vents can reach temperatures of hundreds of degrees and remain liquid.
Water has a high surface tension caused by the weak interactions, (Van Der Waals Force) between water molecules because it is polar. The apparent elasticity caused by surface tension drives the capillary waves.
Water also has high adhesion properties because of its polar nature.
Capillary action refers to the tendency of water to move up a narrow tube against the force of gravity. This property is relied upon by all vascular plants, such as trees.
Water is a very strong solvent, referred to as the universal solvent, dissolving many types of substances. Substances that will mix well and dissolve in water, e.g. salts, sugars, acids, alkalis, and some gases: especially oxygen, carbon dioxide (carbonation), are known as "hydrophilic" (water-loving) substances, while those that do not mix well with water (e.g. fats and oils), are known as "hydrophobic" (water-fearing) substances.
All the major components in cells (proteins, DNA and polysaccharides) are also dissolved in water.
Pure water has a low electrical conductivity, but this increases significantly upon solvation of a small amount of ionic material such as sodium chloride.
Water has the second highest specific heat capacity of any known chemical compound, after ammonia, as well as a high heat of vaporization (40.65 kJ mol−1), both of which are a result of the extensive hydrogen bonding between its molecules. These two unusual properties allow water to moderate Earth's climate by buffering large fluctuations in temperature.
The maximum density of water is at 3.98 °C (39.16 °F). Water becomes even less dense upon freezing, expanding 9%. This causes an unusual phenomenon: ice floats upon water, and so water organisms can live inside a partly frozen pond because the water on the bottom has a temperature of around 4 °C (39 °F).
Water is miscible with many liquids, for example ethanol, in all proportions, forming a single homogeneous liquid. On the other hand, water and most oils are immiscible usually forming layers according to increasing density from the top. As a gas, water vapor is completely miscible with air.
Water forms an azeotrope with many other solvents.
Water can be split by electrolysis into hydrogen and oxygen.
As an oxide of hydrogen, water is formed when hydrogen or hydrogen-containing compounds burn or react with oxygen or oxygen-containing compounds. Water is not a fuel, it is an end-product of the combustion of hydrogen. The energy required to split water into hydrogen and oxygen by electrolysis or any other means is greater than the energy released when the hydrogen and oxygen recombine.
Elements which are more electropositive than hydrogen such as lithium, sodium, calcium, potassium and caesium displace hydrogen from water, forming hydroxides. Being a flammable gas, the hydrogen given off is dangerous and the reaction of water with the more electropositive of these elements is violently explosive.
WATER ON EARTH
Hydrology is the study of the movement, distribution, and quality of water throughout the Earth. The study of the distribution of water is hydrography. The study of the distribution and movement of groundwater is hydrogeology, of glaciers is glaciology, of inland waters is limnology and distribution of oceans is oceanography. Ecological processes with hydrology are in focus of ecohydrology.
The collective mass of water found on, under, and over the surface of a planet is called hydrosphere. Earth's approximate water volume (the total water supply of the world) is 1 360 000 000 km³ (326 000 000 mi³). Of this volume:
1 320 000 000 km³ (316 900 000 mi³ or 97.2%) is in the oceans.
25 000 000 km³ (6 000 000 mi³ or 1.8%) is in glaciers, ice caps and ice sheets.
13 000 000 km³ (3,000,000 mi³ or 0.9%) is groundwater.
250 000 km³ (60,000 mi³ or 0.02%) is fresh water in lakes, inland seas, and rivers.
13 000 km³ (3,100 mi³ or 0.001%) is atmospheric water vapor at any given time.
Groundwater and fresh water are useful or potentially useful to humans as water resources.
Liquid water is found in bodies of water, such as an ocean, sea, lake, river, stream, canal, pond, or puddle. The majority of water on Earth is sea water. Water is also present in the atmosphere in solid, liquid, and vapor states. It also exists as groundwater in aquifers.
The most important geological processes caused by water are: chemical weathering, water erosion, water sediment transport and sedimentation, mudflows, ice erosion and sedimentation by glacier
EFFECTS ON LIFE
From a biological standpoint, water has many distinct properties that are critical for the proliferation of life that set it apart from other substances. It carries out this role by allowing organic compounds to react in ways that ultimately allow replication. All known forms of life depend on water. Water is vital both as a solvent in which many of the body's solutes dissolve and as an essential part of many metabolic processes within the body. Metabolism is the sum total of anabolism and catabolism. In anabolism, water is removed from molecules (through energy requiring enzymatic chemical reactions) in order to grow larger molecules (e.g. starches, triglycerides and proteins for storage of fuels and information). In catabolism, water is used to break bonds in order to generate smaller molecules (e.g. glucose, fatty acids and amino acids to be used for fuels for energy use or other purposes). Water is thus essential and central to these metabolic processes. Therefore, without water, these metabolic processes would cease to exist, leaving us to muse about what processes would be in its place, such as gas absorption, dust collection, etc.
Water is also central to photosynthesis and respiration. Photosynthetic cells use the sun's energy to split off water's hydrogen from oxygen. Hydrogen is combined with CO2 (absorbed from air or water) to form glucose and release oxygen. All living cells use such fuels and oxidize the hydrogen and carbon to capture the sun's energy and reform water and CO2 in the process (cellular respiration).
Water is also central to acid-base neutrality and enzyme function. An acid, a hydrogen ion (H+, that is, a proton) donor, can be neutralized by a base, a proton acceptor such as hydroxide ion (OH−) to form water. Water is considered to be neutral, with a pH (the negative log of the hydrogen ion concentration) of 7. Acids have pH values less than 7 while bases have values greater than 7. Stomach acid (HCl) is useful to digestion. However, its corrosive effect on the esophagus during reflux can temporarily be neutralized by ingestion of a base such as aluminum hydroxide to produce the neutral molecules water and the salt aluminum chloride. Human biochemistry that involves enzymes usually performs optimally around a biologically neutral pH of 7.4.
For example a cell of Escherichia coli contains 70% of water, a human body 60–70%, plant body up to 90% and the body of an adult jellyfish is made up of 94–98% water.
How the Brain Works
Have you ever wondered how we learn? Everything we know is stored in our brain -- one of the most important organs in our entire system. Without it, we wouldn't be able to survive, let alone think and write. Since the 1990s, researchers have begun to understand only a little bit abou the brain's potential. Yet, these discoveries are significant and important. We now know a bit about how our brain works. If we use it well, it can help us to improve ourselves. It will allow us to tap more of our almost unlimited potential. It is true to say that we have unlimited potential. After all, our brain contains around 100 billion neurons, or brain cells. Even if we were to lose a million neurons for every year we live, it would take several hundred years.
But the number of neurons is not as important as the connections between them. It is these connections that help us to create new behaviours and habits. when we leaen something new, new connections take place in our brain. For example, all of us know the way to our own schools. But if we moved to a new home, it would take us some time to get to our school. But over time, we get familiar with the new route. The brain operates much like this -- actions that you are familiar with can be carried out almost automatically, but things that you are not familiar with doing might feel strange unless you keep doing it over and over again. In a laboratory test on mice, scientists designed the rat cages for one group of mice to be complex, with many objects, toys and mazesthat the mice could explore and play with. On the other hand, another group of mice were only put inside a box that had nothing in it. Upon their death, the scientist did some research on the brains of these mice and discovered that those that had been stimulated by a more complex environment had brains that were better developed and heavier than compared with those in a plain box. In fact, studies have shown that mice that are brought up in stimulating environments appear "smarter" than other mice.
Many scientists believe that we only use a small portion of our brains. It is possible for us to start improving our brain potential. It is possible for us to start improving our brain potential. We need to develop better learning habits. Here are two simple suggestions. first, we can start to learn from our experiences. Many of us have learnt to ignore our past experiences. It is important for us to know how we feel, and learn to interpret our feelings positively, so that we can improve ourselves. Many people have interpreted their experiences negatively, and this prevents them from learning .
Second, we can start to learn in a way that our brain prefers. If we are studying for our exams, we could use colours, pictures and drawings to appeal to our sense of sight. We can also act out our subjects in a diferent, creative way to appeal to our sense of sound and feeling. The brain is truly a wonder. We can learn how to make a better use of our brain, so that we can improve ourselves not just in school, but in every aspect of our lives
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