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Common Galaxias

Common galaxias

---- Common galaxias Galaxias maculatus, is a species of fish from the genus galaxiid that is very widespread in the southern hemisphere. The common galaxias is a slim narrow fish with a forked tail and as an adult it lives in freshwater rivers and lakes. Common galaxias grows to a length of 40 to 120 mm, but can grow up to 180 mm.

Habitat

Adults mainly occur in still or slow moving water in the lower parts of coastal streams and rivers. They are also found around the edges of lakes and lagoons. It is often found in schools that are not very large. They can tolerate a wide range of natural conditions.

Reproduction, Life Cycle & Diet

Unless within a lake which is landlocked, the G. maculatus spawn downstream in rivers and streams amongst vegetation on the banks of the estuary regions during a spring tide mainly in Autumn. The eggs remain on the bank (out of the water) until the next spring tide when they hatch into larvae which are swept out to the ocean. For the next 5-6 months the larvae live in the sea and develop into juvenile fish, often referred to as whitebait. When they are about 30 mm in length and 3-4 mm in width they swim up a river on the incoming tide until they reach a suitable habitat where they develop into the adult form. As adults they eat on insects, crustaceans and molluscs. In other words they share the diet of introduced trout. Indeed introduced Trout are a major threat to these fish and in areas where introduced Trout has become naturalised galaxias are scarce. Introduced Trout not only compete for food but also readily eat this species. Common galaxias, therefore, are mostly found in stretches of streams and rivers that are not suitable for introduced Trout. This species lives for about 12 months and usually dies after spawning.

Geography

Common Galaxias are one of the most widely distributes freshwater fish in the world and can be found around throughout New Zealand; in coastal streams in south eastern Australia, Tasmania and some parts of south west Western Australia; in Patagonia Argentina; in the Falkland Islands; and, in some Pacific Islands such as New Caledonia.

Fishing

The juveniles are caught as whitebait while moving upstream and are much valued as a delicacy leading to their protection with licensing and controlled fishing seasons in order to preserve adult populations. Fishing may be both for recreational and commercial activity depending on the geographic location and size of the populations. Some jurisdictions permit fishing of the adults but again under regulation or licence in order to preserve the adult population but others ban it altogether unless the fisher belongs to an indigenous tribe (e.g. New Zealand Maori). For instance, in Tasmania, the adult Common galaxias may only be caught using a pole of a specified maximum size (one metre).

Common Names & Local Names


- Common Galaxias
- Inanga - New Zealand
- Common Jollytail, or just Jollytail - Australia
- Ika - used by Maoris in New Zealand (generic term for fish)
- Puyen - Chile & Argentina

See also


- Whitebait
- galaxiid

External links


- http://www.fishbase.org/identification/specieslist.cfm?famcode=79&areacode=&spines=&fins=
- [http://www.nativefish.asn.au/common_galaxias.html Native Fish Australia] Category:Freshwater fish of Australia Category:Osmeriformes Category:Galaxiidae

Galaxiid

See text Galaxiid is a genus of freshwater fish. Representatives occur throughout the southern hemisphere, including South Africa, South America, New Zealand, Australia, Lord Howe Island, New Caledonia and the Falkland Islands. Some Galaxiids live in freshwater all their lives but many involve a marine cycle for the formation of their juveniles whereby larvae are hatched in a river but are washed downstream to the ocean where they develop and return to rivers as juveniles and further develop and remain as adults.

Fishing

The juveniles of those galaxiid that develop in the ocean and then move into rivers for their adult life are caught as whitebait while moving upstream and are much valued as a delicacy. Adult galaxiids may be caught for food but they are generally not large and their exploitation is usually controlled (Australia) or banned (New Zealand) unless available to indigenous tribes.

Australian Galaxiid

Galaxiid are found around the south eastern seaboard of Australia and in some parts of south western Australia. Species that are common to all areas are:
- Galaxias maculatus (Jollytail galaxias) (Common galaxias) (see also Inanga)
- Galaxias truttaceus (spotted galaxias) (spotted mountain trout) (spotted minnow)
- Galaxias olidus (Mountain Galaxias) (Victoria) Threatened species are:
- Galaxias fuscus (Barred Galaxias) (Victoria)

Tasmanian Galaxiid

15 species of Galaxiid have been found in Tasmania. The most common species are:
- Galaxias brevipinnis (Climbing galaxias) (also known as Koaro)
- Galaxias maculatus While endangered species are:
- Galaxias tanycephalus (Saddled galaxias)
- Galaxias pedderensis (Pedder galaxias)
- Galaxias fontanus (Swan galaxias)
- Galaxias parvus (Swamp galaxias)
- Galaxias auratus (Golden galaxias)
- Galaxiella pusilla (Dwarf galaxias)
- Galaxias johnstoni (Clarence galaxias)
- Paragalaxias julianus (Western paragalaxias)
- Paragalaxias eleotroides (Great Lake paragalaxias)
- Paragalaxias mesotes (Arthurs paragalaxias)
- Paragalaxias dissimilis (Shannon paragalaxias)

New Zealand Galaxiid

19 species of galaxiid have been discovered in New Zealand. Most of these live in freshwater all their lives. However, the larvae of some species develop in the ocean where they form part of the plankton and return to rivers as juveniles where they develop and remain as adults. Galaxiids in New Zealand are:
- Galaxias alepidotus (Giant Kokopu)
- Galaxias argenteus (Giant Kokopu)
- Galaxias attenuatus (Inanga)
- Galaxias brevipinnis (Climbing galaxias) (also known as Koaro)
- Galaxias depressiceps (Flathead galaxias)
- Galaxias fasciatus (Banded Kokopu )
- Galaxias graciliis (Dwarf Inanga)
- Galaxias maculatus (Inanga) (Jollytail, also known as Common Jollytail)
- Galaxias paucispondylus (Alpine galaxias)
- Galaxias postvectis (Shortjaw kokopu)
- Galaxias vulgaris (Canterbury galaxias),
- Neochanna apoda (brown mudfish)
- Neochanna diversus (black mudfish)
- Neochanna burrowsius (Canterbury mudfish)

South American Galaxiid


- Galaxias maculatus (Common galaxias) (Chile and Argentina) Category:Osmeriformes Category:New Zealand fish



Schools

:For other uses of the term school, see school (disambiguation). school (disambiguation) A school is most commonly a place designated for learning. The range of institutions covered by the term varies from country to country. In the United Kingdom, the term school refers primarily to pre-university institutions, and these can, for the most part, be divided into primary schools (sometimes further divided into infant school and junior school), and secondary schools. School performance is monitored by Her Majesty's Inspectorate of Education. Her Majesty's Inspectorate of Education In North America, the term school can refer to any institute of education, at any level, and covers all of the following: preschool (for toddlers), kindergarten, elementary school, middle school (also called intermediate school or junior high school, depending on specific age groups and geographic region), high school, college, university, and graduate school. In the US, school performance through high school is monitored by each state's Department of Education. Many of the earlier public schools in the United States were one-room schools where a single teacher taught seven grades of boys and girls in the same classroom. Beginning in the 1920s, one-room schools were consolidated into multiple classroom facilities with transportation increasingly provided by kid hacks and school buses. In both, a school may also be a partially autonomous or indeed entirely separate institution, not necessarily a part of a system of compulsory public education at all, dedicated to learning within one particular field, such as a school of economics (e.g. the London School of Economics), a school of dance, or a school of journalism. London School of Economics]] In much of continental Europe, the term school usually applies to primary education, with primary schools that last between six and nine years, depending on the country. It also applies to secondary education, with secondary schools often divided between Gymnasiums and vocational schools, which again depending on country and type of school take between three and six years. The term school is rarely used for tertiary education, except for some upper or high schools (German: Hochschule) which are more accurately translated as colleges.

Records

The King's School, in Canterbury in the south east of England, may be the oldest existing school in the world. It was founded in 597 AD.

Criticism

During the twentieth century traditional schools have been the target of widespread criticism. The French sociologist Pierre Bourdieu in his book Distinction: A Social Critique of the Judgement of Taste showed how schools help to reproduce class structure. Schools were accused of inhibiting rather than promoting the learning of children, basically by creating fear. People like A.S. Neill tried to create more libertarian schools (Summerhill) while others like John Holt saw home schooling as an alternative.

Bullying

Bullying can be a common problem within many schools. Programs to target bullying have often been introduced, but these are often unsuccessful.

External links

Pro-school


- [http://www.greatschools.net greatschools.net]
- [http://www.eschoolsearch.com/ eschoolsearch.com]

Against school


- [http://www.johntaylorgatto.com/historytour/history1.htm John Taylor Gatto, former New York State & New York City Teacher of the Year]
- [http://www.school-survival.net School Survival - Support site for kids who hate school]

Others


- [http://www.whocanteach.com Tutors Network] Category: Education ko:학교 ms:Sekolah ja:学校 simple:School

Spawn

:This article is about biological spawning. For other meanings of the word spawn, see spawn (disambiguation). spawn (disambiguation) Spawning is the production or depositing of eggs in large numbers by aquatic animals.

Types of Egg-Layers


- Egg Scatters
- Next Builders
- Egg Hangers
- MouthBreeders
- Egg Buriers

Spawn Cycle

Egg

An egg sac or collection can be called a 'redd' as in 'salmon redd' for the eggs attached to the stream bottom.

Alevin

A newly-hatched fish in the larval stage, one which has not yet emerged from the nesting area. Alevins will have a noticeable yolk sac, and need this yolk sac while their digestive systems are developing. At this stage, the fish are not prepared to hunt live prey, and are completely dependent on the yolk sacs.

Fry

A fry is a recently-hatched fish, but one which has fully absorbed its yolk sac and can now hunt and consume live food.

Parr

A parr is a juvenile fish, one preparing to leave the fresh waters of its home.

Smolt

A smolt is a juvenile fish. This is the stage where Salmonid grow scales and begin their trek to their salt water environment.

Grilse

A young fish which is returning to its spawning grounds at a very young age.

See also


- reproduction. Category:Biological reproduction

Estuary

An estuary is a semi-enclosed coastal body of water which has a free connection with the open sea and within which sea water mixes with fresh water. The key feature of an estuary is that it is a mixing place for sea water and a significantly-sized river to supply fresh water. A tide is a necessary component to maintain a dynamic relationship between the two waters. Though something in the nature of an estuary can exist in a non-tidal sea, such areas go by names such as lagoon, étang or laguna. In non-tidal seas, the rivers naturally form deltas rather than estuaries. An estuary is typically the tidal mouth of a river, and estuaries are often characterised by sedimentation of silt which usually comes mainly from the sea though in some cases, that from the river predominates. The sand and mud banks and marshes are relied upon as habitat by, for example, wading birds. Estuaries are more likely to occur on submerged coasts, where the sea level has risen in relation to the land, as this process floods valleys to form rias and fjords. These can become estuaries if there is a significant river flowing into them. Estuary is also a term used to describe the region of the Thames River and adjoining communities east of Central London in the United Kingdom. The term 'Estuary English' is frequently used to describe the accent of the people in this region, though it has since spread across South East England. It is sometimes mistaken for the Cockney accent by listeners unfamiliar with the varieties.

See also


- Brackish water
- :Category:Estuaries
- Firth
- List of waterways
- Chesapeake Bay
- Hudson River

References


- Pritchard, D. W. (1967) What is an estuary: physical viewpoint. p. 3–5 in: G. H. Lauf (ed.) Estuaries, A.A.A.S. Publ. No. 83, Washington, D.C. Category:Bodies of water Category:Geodesy Category:Water

Spring Tide

The tide is the regular rising and falling of the ocean's surface caused by changes in gravitational forces external to the Earth. The main changing gravitational field is due to the Moon while a lesser field is caused by the Sun. Since tides generate currents of conducting fluids within the Earth's magnetic field, they affect in return the magnetic field itself. The loss of rotational energy of the earth, due to friction within the tides, and the gravitational effects caused by tidal deformations of the earth's body, are responsible for the slowdown of the earth's rotation and the increase of the distance to the moon, see Tidal force.

Tidal terminology

Tidal force Tidal force The maximum water level is called "high tide" or "high water" and the minimum level is "low tide" or "low water". High water occurs as two bulges in the height of the oceans; one bulge faces the moon and the other, on the opposite side of the earth, faces away from the moon. For an explanation see below under Tidal physics. There are two low waters positioned at about 90° of longitude from the high waters. At any given point on the ocean, there are normally two high tides and two low tides each day. The common names of the two high tides are the "high high" tide and the "low high" tide; the two low tides are called the "high low" tide and the "low low" tide. On average, high tides occur 12 hours 24 minutes apart. The 12 hours is due to the Earth's rotation, and the 24 minutes to the Moon's orbit. The 12 hours is half of a solar day and the 24 minutes is half of a lunar extension, which is 1/ (29-day lunar cycle). The lunar cycle is what is tracked by tide clocks. The time between high tide and low tide, when the water level is falling, is called the "ebb". The time between low tide and high tide, when the tide is rising, is called "flow" or "flood". tide clock The height of the high and low tides (relative to mean sea level) also varies. Around new and full Moon when the Sun, Moon and Earth form a line, the tidal forces due to the Sun reinforce those of the Moon, due to the syzygy found at those times. The tides' range is then at its maximum: this is called the "spring tide", or just "springs" and is derived not from the season of spring but rather from the German verb springen, meaning "to leap up". When the Moon is at first quarter or third quarter, the sun and moon are at 90° to each other and the forces due to the Sun partially cancel out those of the Moon. At these points in the Lunar cycle, the tide's range is at its minimum: this is called the "neap tide", or "neaps". Spring tides result in high waters that are higher than average, low waters that are lower than average, slack water time that is shorter than average and stronger tidal currents than average. Neaps result in less extreme tidal conditions. Normally there is a seven day interval between springs and neaps. The relative distance of the Moon from the Earth also affects tide heights: When the Moon is at perigee the range increases, and when it is at apogee the range is reduced. Every 7½ lunations, perigee and (alternately) either a new or full Moon coincide; at these times the range of tide heights is greatest of all, and if a storm happens to be moving onshore at this time, the consequences (in the form of property damage, etc.) can be especially severe (surfers are aware of this, and will often intentionally go out to sea during these times, as the waves are more spectacular than ever). The effect is enhanced even further if the line-up of the Sun, Earth and Moon is so exact that a solar or lunar eclipse occurs concomitant with perigee.

Timing

In most places there is a delay between the phases of the Moon and its effect on the tide. Springs and neaps in the North Sea, for example, are two days behind the new/full Moon and first/third quarter, respectively. The reason for this is that the tide originates in the southern oceans, the only place on the globe where a circumventing wave (as caused by the tidal force of the Moon) can travel unimpeded by land. The resulting effect on the amplitude, or height, of the tide travels across the oceans. It is known that it travels as a single broad wave pulse northwards over the Atlantic. This causes relatively low tidal ranges in some locations (nodes) and high ones in other places. This is not to be confused with tidal ranges caused by local geography, as can be found in Nova Scotia, Bristol, the Channel Islands, and the English Channel. In these places tidal ranges can be over 10 metres. The Atlantic tidal wave arrives after approximately a day in the English Channel area of the European coast and needs another day to go around the British Isles in order to have an effect in the North Sea. Peaks and lows of the Channel wave and North Sea wave meet in the Strait of Dover at about the same time but generally favour a current in the direction of the North Sea. The exact time and height of the tide at a particular coastal point is also greatly influenced by the local topography. There are some extreme cases: the Bay of Fundy, on the east coast of Canada, features the largest well-documented tidal ranges in the world, 16 metres (53 feet), because of the shape of the bay. Southampton in the United Kingdom has a double high tide caused by the flow of water around the Isle of Wight, and Weymouth, Dorset has a double low tide because of the Isle of Portland. Ungava Bay in Nunavut, north eastern Canada, is believed by some experts to have higher tidal ranges than the Bay of Fundy (about 17 metres or 56 feet), but it is free of pack ice for only about four months every year, whereas the Bay of Fundy rarely freezes even in the winter. There are only very slight tides in the Mediterranean Sea and the Baltic Sea due to their narrow connections with the Atlantic Ocean. Extremely small tides also occur for the same reason in the Gulf of Mexico and Sea of Japan. On the southern coast of Australia, because the coast is extremely straight (partly due to the tiny quantities of runoff flowing from rivers), tidal ranges are equally small.

Tidal physics

Ignoring external forces, the ocean's surface defines a geopotential surface or geoid, where the gravitational force is directly towards the centre of the Earth and there is no net lateral force and hence no flow of water. Now consider the effect of added external, massive bodies such as the Moon and Sun. These massive bodies have strong gravitational fields that diminish with distance in space. It is the spatial differences in these fields that deform the geoid shape. This deformation has a fixed orientation relative to the influencing body and the rotation of the Earth relative to this shape drives the tides around. Gravitational forces follow the inverse-square law (force is inversely proportional to the square of the distance), but tidal forces are inversely proportional to the cube of the distance. The Sun's gravitational pull on Earth is 179 times bigger than the Moon's, but because of its much greater distance, the Sun's tidal effect is smaller than the Moon's (about 46% as strong). For simplicity, the next few sections use the word "Moon" where also "Sun" can be understood. cube, this diagram shows the Moon's gravity differential over the thickness of the shell.]] cube at the surface of the earth is known as the Tidal Generating Force. This is the primary mechanism that drives tidal action and explains two bulges, accounting for two high tides per day. Other forces, such as the Earth and Moon revolving around each other, and the Sun's gravity also add to tidal action.]]
Since the Earth's crust is solid, it moves with everything inside as one whole, as defined by the average force on it. For a geoid shape this average force is equal to the force on its centre. The water at the surface is free to move following forces on its particles. It is the difference between the forces at the Earth's centre and surface which determine the effective tidal force. At the point right "under" the Moon (the sub-lunar point), the water is closer than the solid Earth; so it is pulled more and rises. On the opposite side of the Earth, facing away from the Moon (the antipodal point), the water is farther than the solid earth, so it is pulled less and moves away from Earth, rising as well. On the lateral sides, the water is pulled in a slightly different direction than at the centre. The vectorial difference with the force at the centre points almost straight inwards to Earth. It can be shown that the forces at the sub-lunar and antipodal points are approximately equal and that the inward forces at the sides are about half that size. Somewhere in between there is a point where the tidal force is parallel to the Earth's surface. Those parallel components actually contribute most to the formation of tides, since the water particles are free to follow. The actual force on a particle is only about a ten millionth of the force caused by the Earth's gravity. These minute forces all work together:
- pull up under and away from the Moon
- pull down at the sides
- pull towards the sub-lunar and antipodal points at intermediate points So two bulges are formed pointing towards the Moon just under it and away from it on Earth's far side.

Tidal amplitude and cycle time

Since the Earth rotates relative to the Moon in one lunar day (24 hours, 48 minutes), each of the two bulges travels around at that speed, leading to one high tide every 12 hours and 24 minutes. The theoretical amplitude of oceanic tides due to the Moon is about 54 cm at the highest point. This is the amplitude that would be reached if the ocean were uniform with no landmasses and Earth not rotating. The Sun similarly causes tides, of which the theoretical amplitude is about 25 cm (46% of that of the Moon) and the cycle time is 12 hours. At spring tide the two effects add to each other to a theoretical level of 79 cm, while at neap tide the theoretical level is reduced to 29 cm. Real amplitudes differ considerably, not only because of global topography as explained above, but also because the natural period of the oceans is in the same order of magnitude as the rotation period: about 30 hours (by comparison, the natural period of the Earth's crust is about 57 minutes). This means that, if the Moon suddenly vanished, the level of the oceans would oscillate with a period of 30 hours with a slowly decreasing amplitude while dissipating the stored energy. This 30 hour value is a simple function of terrestrial gravity and the average depth of the oceans. The distances of Earth from the Moon or the Sun vary, because the orbits are not circular, but elliptical. This causes a variation in the tidal force and theoretical amplitude of about ±18% for the Moon and ±5% for the Sun. So if both are in closest position and aligned, the theoretical amplitude would reach 93 cm.

Tidal lag

Because the Moon's tidal forces drive the oceans with a period of about 12.42 hours (half of the Earth's synodic period of rotation), which is considerably less than the natural period of the oceans, complex resonance phenomena take place. The lag between the Moon's passage and the tidal response varies between 2 hours in the southern oceans, to two days in the North Sea. The global average tidal lag is six hours (which means low tide occurs when the Moon is at its zenith or its nadir, a result that goes against common intuition). Tidal lag and the transfer of momentum between sea and land causes the Earth's rotation to slow down and the Moon to be moved further away in a process known as tidal acceleration.

Alternative explanation

tidal acceleration Some other explanations in articles on the physics of tides include the (apparent) centrifugal force on the Earth in its orbit around the common centre of mass (the barycentre) with the Moon. The barycentre is located at about ¾ of the radius from the Earth's centre. It is important to note that the Earth has no "rotation" around this point. It just "displaces" around this point in a circular way (see figure). Every point on Earth has the same angular velocity and the same radius of orbit, but with a displaced centre. So the centrifugal force is uniform and does not contribute to the tides. However, this uniform centrifugal force is just equal (but with opposite sign) to the gravitational force acting on the centre of mass of Earth. So subtracting the gravitational force at the centre of Earth from the local gravitational forces at the surface, has the same effect as adding the (uniform) centrifugal forces. Although these two explanations seem very different, they yield the same results.

Tides & fluids

Tides and tidal effects happen in general whenever a mass with some volume moves in a gravitational field that is not uniform. This is, they always happen. For example, in one way or the other, all objects moving in space will see some form of tidal forces. By acting on an ideal rigid body, by definition tides will not deform the body. Many bodies which are moving within the solar system, for example, are not rigid but merely balls of gas or fluids, hovering in empty space (Sometimes they have a very thin solid crust). Tidal forces generate pressure differences between different volumes within such objects, and thus generate material currents on or within such bodies. The following argument applies in general to all such bodies, but the discussion here is restricted to a simplified Earth - Moon system (the sun also generates tides in real life, which are about half as strong as the moon's tides). The moon's tidal effects generate an acceleration field at the surface regions of the earth which point in its direction or the opposite direction. This field is equivalent in strength to the weight of one tenth of a microgram per kilogram material. In other words, each kilogram of material at the surface of the earth experiences an "upward" force that is equivalent to the weight of one tenth of a microgram. It is perfectly clear that nothing starts to move upward because of this. What happens instead, especially within fluids, is a change in the statical pressure within the fluid, because the masses on top lose a little bit of weight. There will be a pressure difference to neighbouring regions, and a material current will start to flow into this regions, until the pressure difference due to tide is balanced by a higher level of the fluids surface. In the earth's oceans, the secondary effects of the material currents amplify the tidal effects by as much as a factor of 20. An equipotential surface of the ocean in a tide region would be 2 ft (60 cm) above normal level, but some coastlines experience tides of 40 ft (12 m) or more. It is important to notice that pressure differences and thus material currents are not only generated in the earth's oceans, but in the interior of the earth as well. By the MHD effect, the material currents generated by the tides will also affect the earth's electromagnetic field. This is seen in real life. The tides continuously excite (seismic) waves within the earth which can be measured by seismology.

Tides and navigation

Tidal flows are of profound importance in navigation and very significant errors in position will occur if tides are not taken into account. Tidal heights are also very important; for example many rivers and harbours have a shallow "bar" at the entrance which will prevent boats with significant draught from entering at certain states of the tide. Tidal flow can be found by looking at a tidal chart or tidal stream atlas for the area of interest. Tidal charts come in sets, each diagram of the set covering a single hour between one high tide and another (they ignore the extra 24 minutes) and give the average tidal flow for that one hour. An arrow on the tidal chart indicates direction and two numbers are given: average flow (usually in knots) for spring tides and neap tides respectively. If a tidal chart is not available, most nautical charts have "tidal diamonds" which relate specific points on the chart to a table of data giving direction and speed of tidal flow. Standard procedure is to calculate a "dead reckoning" position (or DR) from distance and direction of travel and mark this on the chart (with a vertical cross like a plus sign) and then draw in a line from the DR in the direction of the tide. Measuring the distance the tide will have moved the boat along this line then gives an "estimated position" or EP (traditionally marked with a dot in a triangle). Nautical charts display the "charted depth" of the water at specific locations and on contours. These depths are relative to "chart datum", which is the level of water at the lowest possible astronomical tide (tides may be lower or higher for meteorological reasons) and are therefore the minumum water depth possible during the tidal cycle. "Drying heights" may also be shown on the chart. These are the heights of the exposed seabed at the lowest astronomical tide. Heights and times of low and high tide on each day are published in "tide tables". The actual depth of water at the given points at high or low water can easily be calculated by adding the charted depth to the published height of the tide. The water depth for times other than high or low water can be derived from tidal curves published for major ports. If an accurate curve is not available, the rule of twelfths can be used. This approximation works on the basis that the increase in depth in the six hours between low and high tide will follow this simple rule: first hour - 1/12, second - 2/12, third - 3/12, fourth - 3/12, fifth - 2/12, sixth - 1/12. (N.B. It would be foolish to attempt navigation without some training and the "Rule of Twelfths " in particular should be used with caution)

Other tides

In addition to oceanic tides, there are atmospheric tides as well as terrestrial tides (land tides), affecting the rocky mass of the Earth. Atmospheric tides may be negligible for everyday phenomena, drowned by the much more important effects of weather and the solar thermal tides. However, there is strictly no upper limit to the Earth's atmosphere, and the tidal pull increases with the distance from the Earth's centre. Theoretically, the Earth's atmosphere extends beyond the Roche limit of the Earth in the Moon's gravitational field. Since the outer extremely thin layers of the atmosphere are in equilibrium with the layers below, the long term effects may not be easily neglected. This means, if the extremely thin outer layers are steadily siphoned away, the material is re-supplied by lower layers, causing an altogether constant small loss of material. The Earth's crust, on the other hand, rises and falls imperceptibly in response to the Moon's solicitation. The amplitude of terrestrial tides can reach about 55 cm at the equator (15 cm of which are due to the Sun), and they are nearly in phase with the Moon (the tidal lag is about two hours only) - which means that they reinforce the apparent oceanic tides. While negligible for most human activities, terrestrial tides need to be taken in account in the case of some particle physics experimental equipments ([http://news-service.stanford.edu/news/2000/march29/linac-329.html Stanford online]). For instance, at the CERN or SLAC, the very large particle accelerators are designed while taking terrestrial tides into account for proper operation. Indeed, despite their kilometre-range dimension, centimetric deformations might lead to their malfunctioning as a physics experimental apparatus. Among the effects that need to be taken into account are : [http://accelconf.web.cern.ch/accelconf/e00/PAPERS/MOP5A04.pdf circumference deformation] for circular accelerators, [http://accelconf.web.cern.ch/accelconf/p93/PDF/PAC1993_0044.PDF particle beam energy]. The first mathematical explanation of tidal forces was given in 1687 by Isaac Newton in the Philosophiae Naturalis Principia Mathematica. Yet [http://it.wikipedia.org/wiki/Lucio_Russo Lucio Russo], an Italian scholar, in his book [http://www.feltrinelli.it/SchedaLibro?id_volume=5000104 Flussi e Riflussi] (yet to be published in English) demonstrates that hellenistic Greeks already had understood tides in terms of the gravitational pull of the Moon and the Sun. In particular it emerges that Seleuc of Babylon (2 B.C.) used his gravitational explanation to prove that it was the Earth to revolve around the Sun, not the opposite. Tsunami, the large waves that occur after earthquakes, are sometimes called tidal waves, but have nothing to do with the tides. Other phenomena unrelated to tides but using the word tide are rip tide, storm tide, hurricane tide, and red tide. The term tidal wave appears to be disappearing from popular usage.

See also


- Coastal erosion
- Hough function
- Primitive equations
- Storm tide
- Tidal bore
- Tidal island
- Tidal resonance
- Rip tide
- Tide pool
- Slack water
- Tidal power
- Red Tide

External links


- [http://www.jal.cc.il.us/~mikolajsawicki/Tides_new2.pdf "Myths about Gravity and Tides" - an extended and revised version of the paper originally published in “The Physics Teacher” 37, October 1999, pp. 438 - 441.]
- [http://www.lhup.edu/~dsimanek/scenario/tides.htm Misconceptions about tides]
- [http://www.co-ops.nos.noaa.gov/restles3.html Direct and opposite tides, from the Center for Operational Oceanographic Products and Services] (This site uses the concept of centrifugal force.)
- [http://aiuas3.unibe.ch/dpgm/zm_graph_tide.html Earth tides calculator] Category:Physical oceanography Category:Tide ko:조석현상 ja:潮汐 zh-min-nan:Lâu-chúi

Larvae

The word Larvae also is the plural of larva, the juvenile form of animals with indirect development. See larva. ----- In Roman mythology, the larvae or lemures were the spectres or spirits of the dead; they were the malignant version of the lares. Some Roman writers describe lemures as the common name for all the spirits of the dead, and divide them into two classes: the lares, or the benevolent souls of the family, which haunted and guarded the domus or household, and the larvae, or the restless and fearful souls of wicked men. But the more common idea was that the Lemures and Larvae were the same. They were said to wander about at night and to torment and frighten the living. On May 9, 11, and 13, the Lemuralia or Lemuria, the Feast of the Lemures, occurred, when black beans were offered to the Larvae in the hopes of propitiating them; loud noises were also used to frighten them away. Lemurs were so named by Linnaeus for their big eyes, noctural habits and unearthly noises they make at night. Some species of lemur were identified by their call before scientists had seen one.

Singular

The singular form of larvae is larva in both Latin and English. The singular of lemures is lemur in Latin; there is no commonly-accepted English singular form. Dungeons & Dragons and some other fantasy worlds have adopted lemure as the singular, following English singularization rules and therefore presumably pronounced as demure, immure, etc.

Trivia

An artist working drawing the Magic: The Gathering card Hyalopterous Lemure, based on the card name only, accidentally drew a lemur (a small, cuddly-looking animal) instead of a lemure (a spirit of the dead), turning what was supposed to be a terrible monster into a moth-winged teddy bear.[http://www.wizards.com/default.asp?x=mtgcom/arcana/340]

Juvenile

The word juvenile has several meanings:
- A juvenile is an individual organism that has not yet reached its adult form, maturity or size. A human is called a child.
- Juvenile is a rap artist.
- A juvenile is a legal term referring in most jurisdictions to a person under the age of 18. A juvenile delinquent in this context is a juvenile who commits a criminal act.

Insects


Subclass: Apterygota :Orders :
- Archaeognatha (Bristletails) :
- Thysanura (Silverfish) :
- Monura - extinct Subclass: Pterygota :
- Infraclass: "Paleoptera" (paraphyletic) ::Orders ::
- Ephemeroptera (mayflies) ::
- Protodonata - extinct ::
- Odonata (dragonflies and damselflies) ::
- Diaphanopteroidea - extinct ::
- Palaeodictyoptera - extinct ::
- Megasecoptera - extinct ::
- Archodonata - extinct :
- Infraclass: Neoptera ::Orders ::
- Blattodea (cockroaches) ::
- Isoptera (termites) ::
- Mantodea (mantids) ::
- Dermaptera (earwigs) ::
- Plecoptera (stoneflies) ::
- Protorthoptera - extinct ::
- Orthoptera (grasshoppers, etc) ::
- Phasmatodea (walking sticks) ::
- Caloneroptera - extinct ::
- Titanoptera - extinct ::
- Embioptera (webspinners) ::
- Zoraptera ::
- Grylloblattodea ::
- Mantophasmatodea (gladiators) :
- Superorder: Exopterygota ::Orders ::
- Psocoptera (booklice, barklice) ::
- Thysanoptera (thrips) ::
- Phthiraptera (lice) ::
- Hemiptera (true bugs) :
- Superorder: Endopterygota ::Orders ::
- Raphidioptera (snakeflies) ::
- Megaloptera (alderflies, etc.) ::
- Neuroptera (net-veined insects) ::
- Coleoptera (beetles) ::
- Strepsiptera (twisted-winged parasites) ::
- Mecoptera (scorpionflies, etc.) ::
- Siphonaptera (fleas) ::
- Diptera (true flies) ::
- Trichoptera (caddisflies) ::
- Lepidoptera (butterflies, moths) ::
- Hymenoptera (ants, bees, etc.) ::
- Protodiptera extinct ::Incertae sedis ::
- Glosselytrodea extinct ::
- Miomoptera - extinct Insects are invertebrate animals of the Class Insecta, the largest and (on land) most widely distributed taxon within the Phylum Arthropoda. Insects comprise the most diverse group of animals on the earth, with over 800,000 species described—more than all other animal groups combined: "Indeed, in no one of her works has Nature more fully displayed her exhaustless ingenuity," Pliny exclaimed. Insects may be found in nearly all environments on the planet, although only a small number of species have adapted to life in the oceans where crustaceans tend to predominate. There are approximately 5,000 dragonfly species, 2,000 praying mantis, 20,000 grasshopper, 170,000 butterfly and moth, 120,000 fly, 82,000 true bug, 350,000 beetle, and 110,000 bee and ant species. Estimates of the total number of current species, including those not yet known to science, range from two to thirty million, with most authorities favoring a figure midway between these extremes. The study of insects is called entomology.

Relationship to other arthropods

A few smaller groups with similar body plans, such as springtails (Collembola), are united with the insects in the Subphylum Hexapoda. The true insects (that is, species classified in the Class Insecta) are distinguished from all other arthropods in part by having ectognathous, or exposed, mouthparts and eleven (11) abdominal segments. Most species, but by no means all, have wings as adults. Terrestrial arthropods, such as centipedes, millipedes, scorpions and spiders, are sometimes confused with insects due to the fact that both have similar body plans, sharing (as do all arthropods) a jointed exoskeleton.

Morphology and development

Insects range in size from less than a millimeter to over 18 centimeters (some walkingsticks) in length. Insects possess segmented bodies supported by an exoskeleton, a hard outer covering made mostly of chitin. The body is divided into a head, a thorax, and an abdomen. The head supports a pair of sensory antennae, a pair of compound eyes, and a mouth. The thorax has six legs (one pair per segment) and wings (if present in the species). The abdomen has excretory and reproductive structures. Insects have a complete digestive system. That is, their digestive system consists basically of a tube that runs from mouth to anus, contrasting with the incomplete digestive systems found in many simpler invertebrates. The excretory system consists of Malpighian tubules for the removal of nitrogenous wastes and the hindgut for osmoregulation. At the end of the hindgut, insects are able to reabsorb water along with potassium and sodium ions. Therefore, insects don't usually excrete water with their feces, a fact which allows them to store water in the body. This process of reabsorption enables them to withstand hot, dry environments. osmoregulation Most insects have two pairs of wings located on the second and third thoracic segments. Insects are the only invertebrate group to have developed flight, and this has played an important part in their success. The winged insects, and their secondarily wingless relatives, make up the subclass Pterygota. Insect flight is not very well understood, relying heavily on turbulent atmospheric effects. In more primitive insects it tends to rely heavily on direct flight muscles, which act upon the wing structure. More advanced flyers, which make up the Neoptera, generally have wings that can be folded over their back, keeping them out of the way when not in use. In these insects, the wings are powered mainly by indirect flight muscles that move the wings by stressing the thorax wall. These muscles are able to contract when stretched without nervous impulses, allowing the wings to beat much faster than would be otherwise possible. Insects use tracheal respiration in order to transport oxygen through their bodies. Openings on the surface of the body called spiracles lead to the tubular tracheal system. Air reaches internal tissues via this system of branching trachea. The circulatory system of insects, like that of other arthropods, is open: the heart pumps the hemolymph through arteries to open spaces surrounding the internal organs; when the heart relaxes, the hemolymph seeps back into the heart. Insects hatch from eggs, and undergo a series of moults as they develop and grow in size. This manner of growth is necessitated by the exoskeleton. Moulting is a process by which the individual escapes the confines of the exoskeleton in order to increase in size, then grows a new outer covering. In most types of insects, the young, called nymphs, are basically similar in form to the adults (an example is the grasshopper), though wings are not developed until the adult stage. This is called incomplete metamorphosis. Complete metamorphosis distinguishes the Endopterygota, which includes many of the most successful insect groups. In these species, an egg hatches to produce a larva, which is generally worm-like in form. The larva grows and eventually becomes a pupa, a stage sealed within a cocoon or chrysalis in some species. In the pupal stage, the insect undergoes considerable change in form to emerge as an adult, or imago. Butterflies are an example of an insect that undergoes complete metamorphosis. imago.]]

Behavior

Many insects possess very refined organs of perception. In some cases, their senses can be more capable than humans. For example, bees can see in the ultraviolet spectrum, and male moths have a specialized sense of smell that enables them to detect the pheromones of female moths over distances of many kilometers. Social insects, such as the ant and the bee, are the most familiar species of eusocial animal. They live together in large well-organized colonies that are so tightly integrated and genetically similar the colonies are sometimes considered superorganisms.

Roles in the environment and human society

Many insects are considered pests by humans, because they transmit diseases (mosquitos, flies), damage structures (termites), or destroy agricultural goods (locusts, weevils). Many entomologists are involved in various forms of pest control, often using insecticides, but more and more relying on methods of biocontrol. Although pest insects attract the most attention, many insects are beneficial to the environment and to humans. Some pollinate flowering plants (for example wasps, bees, butterflies, ants). Pollination is a trade between plants which need to reproduce, and pollinators which receive rewards of nectar and pollen. A serious environmental problem today is the decline of populations of pollinator insects, and a number of species of insects are now cultured primarily for pollination management in order to have sufficient pollinators in the field, orchard or greenhouse at bloom time. Insects also produce useful substances such as honey, wax, lacquer or silk. Honeybees, (pictured above) have been cultured by humans for thousands of years for honey, although contracting for crop pollination is becoming more significant for beekeepers. The silkworm has greatly affected human history as silk-driven trade established relationships between China and the rest of the world. Fly larvae (maggots) were formerly used to treat wounds to prevent or stop gangrene, as they would only consume dead flesh. This treatment is finding modern usage in some hospitals. Insect larvae of various kinds are also commonly used as fishing bait. In some parts of the world, insects are used for human food ("Entomophagy"), while being a taboo in other places. There are proponents of developing this use to provide a major source of protein in human nutrition. Since it is impossible to entirely eliminate pest insects from the human food chain, insects already are present in many foods, especially grains. Most people do not realize that food laws in many countries do not prohibit insect parts in food, but rather limit the quantity. According to cultural materialist anthropologist Marvin Harris, the eating of insects is taboo in cultures that have protein sources that require less work like farm birds or cattle. Many insects, especially beetles, are scavengers, feeding on dead animals and fallen trees, recycling the biological materials into forms found useful by other organisms. The ancient Egyptian religion adored beetles and represented them as scarabeums. Although mostly unnoticed by most humans, arguably the most useful of all insects are insectivores, those that feed on other insects. Many insects, such as grasshoppers can potentially reproduce so fast that they could literally bury the earth in a single season. However there are hundreds of other insect species that feed on grasshopper eggs, and some that feed on grasshopper adults. This role in ecology is usually assumed to be primarily one of birds, but insects, though less glamorous, are much more significant. For any pest insect one can name, there is a species of wasp that is either a parasitoid or predator upon that pest, and plays a significant role in controlling it. Human attempts to control pests by insecticides can backfire, because important but unrecognized insects already helping to control pest populations are also killed by the poison, leading eventually to population explosions of the pest species.

Fossils and evolution

predator The relationships of insects are unclear. Although traditionally grouped with millipedes and centipedes, evidence has emerged favoring a relationship with the crustaceans. Apart from some tantalizing Devonian fragments, insects first appear suddenly in the fossil record during the very start of the Late Carboniferous period, Early Bashkirian age, about 350 million years ago. As they are already specialized, and represented by more than half a dozen different orders, their anscestry must be sought earlier the Carboniferous, if not the Devonian. Little is known about the origin of insect flight, since the earliest winged insects appear to be capable fliers. Wings themselves are now thought to be highly modified gills, and some insects (e.g. the Palaeodictyoptera) had an additional pair of winglets attaching to the first segment of the thorax, for a total of three pairs. Late Carboniferous and Early Permian insect orders include both several current very long-lived groups (mayflies, (Ephemeroptera), dragonflies (Odonata), cockroaches (Blattodea), and Orthoptera (grasshoppers and their relatives)) and a number of Paleozoic forms. During this time, some giant dragonfly-like forms - e.g. Meganeura and Meganeuropsis (Order Protodonata) and Mazothairos (Order Palaeodictyoptera) - reached wingspans of 55 to 70 cm, making them far larger than any living insect. The Permian, around 270 million years, saw the development of most extant orders; while many of the early groups became extinct during the Permian-Triassic extinction event, the largest mass extinction in the history of the earth. The remarkably successful Hymenopterans appeared in the Cretaceous but achieved their diversity more recently, in the Cenozoic. A number of highly successful insect groups — especially the Hymenoptera and Lepidoptera (butterflies), as well as many types of Diptera (flies) and Coleoptera (beetles) — evolved in conjunction with flowering plants, a powerful illustration of co-evolution. Many modern insect genera developed during the Cenozoic; from this period on we find insects preserved in amber, often in perfect condition and easily compared with modern species. The study of fossilized insects is called paleoentomology.

References


- — a classic textbook in North America
- — an up to date review of the evolutionary history of the insects

Quotes


- "Something in the insect seems to be alien to the habits, morals, and psychology of this world, as if it had come from some other planet: more monstrous, more energetic, more insensate, more atrocious, more infernal than our own." ::—Maurice Maeterlinck (1862–1949)

See also

1949 Cleanly flesh-fly, 4:05 minute film - 8MB xvid in ogg container showing a flesh-fly using its front and back pairs of legs to clean wings and head. The film runs at half speed to enable the viewer to appreciate the fast movements of the animal.
- Animal
- Invertebrate
- Prehistoric insect
- Insect flight

External links


- [http://cmave.usda.ufl.edu/~rmankin/soundlibrary.html Bug Bytes] A reference library of digitized insect sounds.
- [http://www.sonoma.edu/users/r/rank/Bio355/BIOL355inslinks.html Entomological Links] A long list of links about insects
- [http://www.insects.org/index.html INSECTS .org] A shameless promotion of insect appreciation.
- [http://www.food-insects.com/ Insects as Food] by Gene DeFoliart. Information about insects as a food resource.
- [http://www.kendall-bioresearch.co.uk/index.htm Kendall Bioresearch] Bug Index, Featured Bugs, Classification, ID, Fossils, Body-parts, Micro Views, Life Cycles, Pesticide Safety.
- [http://www.ub.es/dpep/meganeura/meganeura.htm Meganeura] Website about insect evolution and fossil record.
- [http://tolweb.org/tree?group=Insecta&contgroup=Hexapoda Tree of Life Project] – Insecta
- [http://ufbir.ifas.ufl.edu/ UF Book of Insect Records], documenting "insect champions" in different categories Category:Arthropods Category:Entomology
- ko:곤충 ms:Serangga ja:昆虫類 simple:Insect th:แมลง

Molluscs

:For the 1997 album by Ween, see The Mollusk.
Caudofoveata
Aplacophora
Polyplacophora - Chitons
Monoplacophora
Bivalvia - Bivalves
Scaphopoda - Tusk shells
Gastropoda - Snails and Slugs
Cephalopoda - Squids, Octopuses, etc.
The molluscs or mollusks are the large and diverse phylum Mollusca, which includes a variety of familiar creatures well-known for their decorative shells or as seafood. These range from tiny snails, clams, and abalone to the octopus and squid (which are considered the most intelligent invertebrates). The giant squid, which until recently had not been observed alive in its adult form is the largest invertebrate although it is likely that the Colossal Squid is even larger. The scientific study of molluscs is called malacology. Molluscs are triploblastic protostomes. The principal body cavity is a blood-filled hemocoel, with an actual coelom present but reduced to vestiges around the hearts, gonads, and metanephridia (kidney-like organs). The body is divided into a head, often with eyes or tentacles, a muscular foot and a visceral mass housing the organs. Molluscs have a mantle, which is a fold of the outer skin lining the shell, and a muscular foot that is used for motion. Many molluscs have their mantle produce a calcium carbonate external shell and their gill extracts oxygen from the water and disposes waste. All species of the phylum Mollusca have a complete digestive tract that starts from the mouth to the anus. Many have a radula, mostly composed of chitin, in the mouth, which allows them to scrape food from the surface by sliding back and forth. Molluscs also have a coelom in which the organs are suspended. Unlike the closely related annelids, molluscs lack body segmentation. Development passes through one or two trochophore stages, one of which (the veliger) is unique to the group. These suggest a close relationship between the molluscs and various other protostomes, notably the Annelids. Mollusc fossils are some of the best known and are found from the Cambrian onwards. There are eight living classes and one class, known only from fossils:
- Class Caudofoveata (deep-sea wormlike creatures; 70 known species); now generally recognized as a subclass of Aplacophora.
- Class Aplacophora (solenogasters, deep-sea wormlike creatures; 250 species)
- Class Polyplacophora (chitons; 600 species, rocky marine shorelines)
- Class Monoplacophora (deep-sea limpet-like creatures; 11 living species)
- Class Bivalvia (also Pelecypoda) (clams, oysters, scallops, mussels; 8,000 species)
- Class Scaphopoda (tusk shells; 350 species, all marine)
- Class Gastropoda (nudibranchs, snails and slugs, limpets, sea hares; sea angel, sea butterfly, Sea Lemon; estimated 40,000 - 150,000 species)
- Class Cephalopoda (squids, octopuses, nautilus, cuttlefish; 786 species, all marine)
- Class † Rostroconchia (fossils; probably more than 1,000 species; probable ancestors of bivalves)

                 Caudofoveata (?)
                 Aplacophora
hypothetical                     Polyplacophora
ancestral                Monoplacophora
mollusc                   Gastropoda
                    Cephalopoda
                    Bivalvia
                    Scaphopoda
Brusca & Brusca (1990) suggest that the bivalves and scaphopods are sister groups, as are the gastropods and cephalopods, so indicated in the relationship diagram above. In this Phylum's level of organization, organ systems from all three primary germ layers can be found: # Nervous System (with brain). # Excretory System (nephridium or nephridia). # Circulatory System (open). # Respiratory System (gills or lungs).
- No skeletal system can be found.

See also


- Important publications on mollusks

References


- Brusca & Brusca, 1990. Invertebrates, Sinauer Associates, Inc., Sunderland, Mass.
- Starr & Taggart, 2002. Biology: The Unity and Diversity of Life, Thomson Learning, inc., Pacific Grove, California.
- [http://www.manandmollusc.net Mollusc Mollusc Mollusks 1999] Category:Animals
- ko:연체동물 ja:軟体動物

Trout

Trout is the common name given to a number of species of freshwater fishes belonging to the salmon family, Salmonidae. All fish properly called trout are members of the subfamily Salmoninae, but the name is used for fish from all three generations in the subfamily: Salmo, which includes Atlantic species; Oncorhynchus, which includes Pacific species; and Salvelinus, which includes fish referred to as Char. Fish referred to as trout include:
- Genus Salmo
  - Adriatic trout - Salmo obtusirostris
  - Brown Trout -Salmo trutta
  - Marmorata or Soča trout - Salmo trutta marmoratus
  - Flathead trout - Salmo platycephalus
  - Ohrid trout - Salmo letnica
  - Sevan trout - Salmo ischchan
- Genus Oncorhynchus
  - Apache trout
  - Cutthroat trout
  - Gila trout
  - Golden Trout
  - Rainbow trout
- Genus Salvelinus (Char)
  - Brook Trout
  - Bull trout
  - Dolly Varden trout
  - Lake trout
  - Silver trout (extinct) Trout are usually found in cool, clear streams and lakes, and are distributed naturally throughout North America, northern Asia and Europe. Several species of trout were introduced to Australia and New Zealand by amateur fishing enthusiasts in the 19th century, contributing to the displacement of native freshwater fish to some extent. Trout have no spines on the fins, and all of them have a small adipose (fatty) fin along the back, near the tail. There are many species, and even more populations that are isolated from each other and morphologically different. However, many of these distinct appearing populations show no significant genetic differences, and therefore what appear to be a large number of species are considered a much smaller number of distinct species by most ichthyologists. The trout found in the eastern United States are a good example of this. The brook trout, the aurora trout and the (extinct) silver trout all have physical characteristics and colourations that distinguish them. Genetic analysis shows however that they are one species, Salvelinus fontinalis. Lake trout (Salvelinus namaycush), like Brook trout, are actually a member of the char genus . It inhabits many of the larger lakes in North America and lives much longer than Rainbow trout which has an average maximum life span of 7 years. Lake trout can live many decades and can grow to more than 60 pounds (27 kg). Lake trout Most trout are restricted to freshwater, but many, like the steelhead (Oncorhynchus mykiss) – which is the same species as the landlocked rainbow trout – spend their adult life in the ocean and then return to spawn in the streams in which they were hatched. This is called anadromous reproduction and is more often seen in salmon. Brook trout, Brown trout, Cutthroat trout, Bull trout, and Arctic char also have populations that run to salt water. Trout generally feed on soft bodied aquatic invertebrates, such as Diptera, mayfly, caddis fly, and stonefly, although larger specimens of trout regularly feed on other fish. As a group, trout are a somewhat bony fish, but the flesh is considered good eating. Additionally, they provide a good fight when caught with a hook and line, and are sought after recreationally. Because of their popularity, trout are often raised on fish farms and introduced into the streams that are most heavily fished. While they can be caught with a normal rod and reel, fly fishing is a distinctive method developed primarily for trout and now extended to other species. Farmed trout and char are also sold commercially. Trout that live in different enviroments can have dramatically different colorations and patterns. Mostly these colors and patterns form as camouflage, based on the surroundings. Trout that run in the sea can look very silvery, while the same "genetic" fish living trapped in an alpine lake could have greenish speckles with far more coloration. It is virtually impossible to define a particular color pattern belonging to a specific breed, however wild fish seem to have more vivid colors and patterns. fly fishing The cutthroat trout has 14 recognized subspecies (depending on your sources), such as the Lahontan cutthroat trout Oncorhynchus clarki henshawi, Bonneville cutthroat trout Oncorhynchus clarki utah, Colorado River cutthroat trout, Yellowstone cutthroat trout.

References


- Trout and Salmon of North America, Robert J. Behnke, Illustrated by Joseph R. Tomelleri, The Free Press, 2002, hardcover, 359 pages, ISBN 0-7432-2220-2 Category:Salmon Category:Salmonidae Category:Cold water fish ja:マス

New Zealand

New Zealand or Aotearoa, the Land of the Long White Cloud, is a country of two large islands and many smaller islands in the south-western Pacific Ocean. New Zealand is notable for its isolation, being separated from Australia on the northwest by the Tasman Sea, some 2,000 km wide. The closest neighbours to the north are New Caledonia, Fiji and Tonga. The population of New Zealand is mostly of European descent, with the indigenous Māori as the largest minority. Non-Māori Polynesian and Asian peoples are also significant minorities, especially in the cities. Officially, Elizabeth II is the Queen of New Zealand and is represented in the country by a non-political Governor-General; though the Queen has no real political influence. Political power is held by the Prime Minister who is leader of the Government in the democratically elected Parliament of New Zealand. The monarch's Realm of New Zealand also includes the Cook Islands and Niue, which are entirely self-governing; Tokelau, which is moving towards self-government, and New Zealand's claim in Antarctica.

History

New Zealand is one of the most recently settled major land masses. Polynesian settlers arrived in their waka some time between 800 and 600 years ago to establish the indigenous Māori culture. Settlement of the Chatham Islands to the south-east of New Zealand produced the Moriori people but it is disputed whether they moved there from New Zealand or elsewhere in Polynesia. Most of New Zealand was divided into tribal territories called rohe, resources within which were controlled by an iwi ('tribe'). Usually no two iwi had overlapping rohe. Māori adapted to eating the local marine resources, flora and fauna for food, hunting the giant flightless moa (which soon became extinct), and ate the Polynesian Rat and kumara (sweet potato), which they introduced to the country. The first Europeans known to reach New Zealand were led by Abel Janszoon Tasman, who sailed up the west coast of the South and North islands in 1642. He named it Staten Landt, believing it to be part of the land Jacob Le Maire had discovered in 1616 off the coast of Chile. Staten Landt appeared on Tasman's first maps of New Zealand, but this was changed by Dutch cartographers to Nova Zeelandia, after the Dutch province of Zeeland, some time after Hendrik Brouwer proved the South American land to be an island in 1643. The Latin Nova Zeelandia became Nieuw Zeeland in Dutch. Lieutenant James Cook subsequently called the archipelago New Zealand, although the names he chose for the North and South islands were rejected, and the main three islands became known as North, Middle and South, with the Middle Island being later called the South Island. Cook began extensive surveys of the islands in 1769, leading to European whaling expeditions and eventually significant European colonisation. From as early as the 1780s, Māori had encounters with European sealers and whalers. Acquisition of muskets by those iwi in close contact with European visitors destabilised the existing balance of power between Māori tribes and there was a temporary but intense period of bloody inter-tribal warfare, known as the Musket Wars, that only ceased when all iwi were so armed. Concern about the exploitation of Māori by Europeans, Church Missionary Society lobbying and French interest in the region led the British to annex New Zealand by Royal Proclamation in January 1840. To legitimise the British annexation, Lieutenant Governor William Hobson had been dispatched in 1839; he hurriedly negotiated the Treaty of Waitangi with northern iwi on his arrival. The Treaty was signed in February, and in recent years it has come to be seen as the founding document of New Zealand. The Māori translation of the treaty promised the Māori tribes "tino rangatiratanga" would be preserved in return for cedeing kawanatanga, which the English versions translates as "chieftainship" for "sovereignty"; the real meanings are now disputed. Disputes over land sales and sovereignty caused the New Zealand land wars which took place between 1845 and 1872. In 1975 the Treaty of Waitangi Act established the Waitangi Tribunal, charged with hearing claims of Crown violations of the Treaty of Waitangi dating back to 1840. Some Māori tribes and the Moriori never signed the treaty. Although New Zealand was initially administered as a part of the Australian colony of New South Wales, it became a colony in its own right in 1841. European settlement progressed more rapidly than anyone anticipated, and settlers soon outnumbered Māori. Self-government was granted to the settler population in 1852. The first capital of New Zealand was Kororareka (known today as Russell) but shortly afterwards moved to Auckland. There were political concerns following the discovery of gold in Central Otago in 1861 that the South Island would form a separate colony. So in 1865 the capital was offically moved to the more central city of Wellington. New Zealand was involved in a Constitutional Convention in March 1891 in Sydney, New South Wales, along with the then-colonies of Australia. This was to consider a potential constitution for the proposed federation between the then-British Colonies of Australasia. New Zealand lost interest in joining Australia in a federation following this convention. New Zealand became an independent dominion on 26 September 1907 by royal proclamation. Full independence was granted by the United Kingdom Parliament with the Statute of Westminster in 1931; it was taken up upon the Statute's adoption by the New Zealand Parliament in 1947. Since then New Zealand has been a sovereign constitutional monarchy within the Commonwealth of Nations.

Politics

New Zealand is a constitutional monarchy with a parliamentary democracy. Under the New Zealand Royal Titles Act (1953), Queen Elizabeth II is Queen of New Zealand and is represented as head of state by the Governor-General, Dame Silvia Cartwright. The New Zealand Parliament has only one chamber, the House of Representatives which usually seats 120 members of Parliament. Parliamentary elections are every three years under a form of proportional representation called Mixed Member Proportional (MMP). The 2005 General Election created an 'overhang' of one extra seat (occupied by the Māori Party), due to that party winning more seats in constituencies than its proportional entitlement. There is no single written constitution; however, the Constitution Act (1986) is the principal formal statement of New Zealand's constitutional structure. The Governor-General has the power to appoint and dismiss Prime Ministers and to dissolve Parliament. The Governor-General also chairs the Executive Council which is a formal committee consisting of all ministers of the Crown. Members of the Executive Council are required to be members of Parliament, and most are also in Cabinet. Cabinet is the most senior policy-making body and is led by the Prime Minister who is also the Parliamentary leader of the governing party or coalition. The current Prime Minister is Helen Clark of the Labour Party. She has served two complete terms as Prime Minister and has begun her third. On 17 October 2005 she announced that she had come to a complex arrangement that guaranteed the support of enough parties for her Labour-led coalition to govern. The core of the coalition is a cabinet consisting of Labour Party ministers and Jim Anderton, the Progressive Party's only MP. In addition to the parties represented in cabinet the leaders of New Zealand First and United Future are to be appointed as Ministers outside Cabinet. An arrangement of this kind has never been attempted before in New Zealand. A further arrangement has been made with the Green Party, which has given a commitment not to vote against the government on confidence and supply. This commitment assures the government of a majority of seven MPs on confidence. The Leader of the Opposition is National Party leader Don Brash who was formerly Governor of the Reserve Bank. Also in opposition are the Māori Party and ACT New Zealand. The highest court in New Zealand is the Supreme Court of New Zealand. The Supreme Court was established in 2004 following the passage of the Supreme Court Act in 2003. The Act abolished the option to appeal Court of Appeal rulings to the Privy Council in London. The current Chief Justice is Dame Sian Elias. New Zealand's judicary also has a High Court which deals with serious criminal offences and civil matters, and a Court of Appeal, as well as subordinate courts.

Foreign relations and military

New Zealand maintains a strong profile on environmental protection, human rights and free trade, particularly for agriculture. New Zealand is a member of the following geo-political organisations: APEC, Commonwealth of Nations, OECD and the United Nations. It has signed up to a number of free trade agreements, of which the most important is Closer Economic Relations with Australia. For its first hundred years, New Zealand followed Britain's lead on foreign policy. "Where she goes, we go, where she stands, we stand", said Prime Minister Michael Savage, in declaring war on Germany on 3 September 1939. However, Britain's inability to protect New Zealand from Japanese aggression in World War II led New Zealand to come under the influence of the United States of America for the generation following the war. New Zealand has traditionally also worked closely with Australia, whose foreign policy followed a similar historical trend. In turn, many Pacific Islands such as Western Samoa have looked to New Zealand's lead. The American influence on New Zealand was weakened by the disappointment with the Vietnam War, the nuclear danger presented by the Cold War, the Sinking of the Rainbow Warrior by France and by disagreements over environmental and agricultural trade issues. New Zealand is a party to the ANZUS security treaty between Australia, New Zealand and the United States. In 1984 New Zealand refused nuclear-powered or nuclear-armed ships access to its ports. In 1986 the United States announced that it was suspending its treaty security obligations to New Zealand pending the restoration of port access. The New Zealand Nuclear Free Zone, Disarmament and Arms Control Act of 1987 prohibits the stationing of nuclear weapons on the territory of New Zealand and the entry into New Zealand waters of nuclear armed or propelled ships. This legislation remains a source of contention and the basis for the United States' continued suspension of treaty obligations to New Zealand. In addition to the various wars between Iwi, and between the British, settlers and Iwi, New Zealand has fought in the Boer War, World War I, (sustaining the highest casualties per head of population of any combatant nation), World War II, the Korean War, the Malayan Emergency (and committed troops, fighters and bombers to the subsequent confrontation with Indonesia), the Vietnam War, the Gulf War and the Afghanistan War and has briefly sent a unit of army engineers to help with rebuilding Iraqi infrastructure. The New Zealand military has three branches: the New Zealand Army, the Royal New Zealand Navy, and the Royal New Zealand Air Force. New Zealand considers its own national defence needs to be modest; it dismantled its air combat capability in 2001. New Zealand has contributed forces to recent regional and global peacekeeping missions, including those in Cyprus, Somalia, Bosnia, the Sinai, Angola, Cambodia, the Iran/Iraq border, Bougainville and East Timor.

Local government and external territories

East Timor The early European settlers divided New Zealand into provinces. These were abolished in 1876 so that government could be centralised for financial reasons. As a result, New Zealand has no separately represented subnational entities such as provinces, states or territories apart from its local government. The spirit of the provinces however still lives on, and there is fierce rivalry exhibited in sporting and cultural events. Since 1876, local government has administered the various regions of New Zealand. In 1989, the government completely reorganised local government, implementing the current two-tier structure of regional councils and territorial authorities. Today New Zealand has 12 regional councils for the administration of environmental and transport matters and 74 territorial authorities that administer roading, sewerage, building consents, and other local matters. The territorial authorities are 16 city councils, 57 district councils, and the Chatham Islands County Council. Four of the territorial councils (one city and three districts) and the Chatham Islands County Council also perform the functions of a regional council and thus are known as unitary authorities. Territorial authority districts are not subdivisions of regional council districts, and a few of them straddle regional council boundaries. Regions are (asterisks denote unitary authorities): Northland, Auckland, Waikato, Bay of Plenty, Gisborne
- , Hawke's Bay, Taranaki, Manawatu-Wanganui, Wellington, Marlborough
- , Nelson
- , Tasman
- , West Coast, Canterbury, Otago, Southland, Chatham Islands
- . As a major South Pacific nation, New Zealand has a close working relationship with many of the smaller Pacific Island nations, and continues a political association with the Cook Islands, Niue, and Tokelau. New Zealand operates Scott Base in its Antarctic territory, the Ross Dependency. Other countries also use Christchurch to support their Antarctic bases and the city is sometimes known as the "Gateway to Antarctica".

Geography

Ross Dependency are visible in the centre of the North Island. The Southern Alps and the rain shadow they create are clearly visible on the South Island]] New Zealand comprises two main islands (simply called the North and South Islands in English, or usually Te-Ika-a-Maui and Te Wai Pounamu in Māori) and a number of smaller islands. The total land area of New Zealand, 268,680 km², is a little less than that of Japan and a little more than the United Kingdom. The country extends more than 1600 km along its main, north-north-east axis. The most significant of the smaller inhabited islands of New Zealand include Stewart Island/Rakiura, Waiheke Island, an island in Auckland's Hauraki Gulf, Great Barrier Island, east of the Hauraki Gulf and the Chatham Islands, named Rekohu by Moriori. The country has extensive marine resources, with the fifth largest Exclusive Economic Zone in the world covering over 4 million km², more than 15 times its land area. The South Island is the largest land mass, and is divided along its length by the Southern Alps, the highest peak of which is Aoraki/Mount Cook, at 3,754 metres (12,316 feet). There are 18 peaks of more than 3,000 metres in the South Island. The North Island is less mountainous than the