A shark tooth is one of the numerous teeth of a shark. A shark tooth contains resistant calcium phosphate materials. Sharks continually shed their teeth. There are four basic types of shark teeth: dense flattened, needle-like, pointed lower with triangular upper, non-functional; the type of tooth that a shark has depends on its feeding habits. In some formations, shark's teeth are a common fossil; these fossils can be analyzed for information on shark biology. Fossil teeth comprise much of the fossil record of the Elasmobranchii, extending back to hundreds of millions of years. Shark teeth are useful in conducting research about the structure of teeth, shark migration patterns, identifying shark species; the most ancient types of sharks date back to 450 million years ago, during the Late Ordovician period, are known by their fossilised teeth. However, the most found fossil shark teeth are from the Cenozoic era. Though sharks are specialized, as a category they have ranged in their adaptations, their teeth reflect this, ranging in form and function.
There are a number of common types of shark teeth. Examples include dense flattened teeth for crushing. Dense flattened teeth are used to crush prey like crustaceans; these sharks include nurse sharks and angel sharks. They are found at the bottom of the ocean floor; this was the first common style of shark tooth, present in the Devonian, four hundred million years ago. Sharks with needle-like teeth feed on small to medium-sized fish, sometimes including small sharks; these teeth are effective for such prey because they can grip their slippery and narrow bodies. Modern examples include bull sharks; these sharks use their teeth to feed on small prey like squid, flounder and hammerhead sharks. This combination of pointed lower teeth with triangular upper teeth are useful for cutting prey that consist of large mammals and fish; the combination of teeth entails serrated edges to cut the larger prey into smaller portions in order to swallow the pieces. The most famously known shark with these teeth is the Great White shark, which feeds on animals such as sea lions, other sharks, small whales.
The teeth of plankton-feeders, such as the basking shark and whale shark, are reduced and non-functional. These sharks filter feed on prey by opening their mouths to let tiny organisms get sucked into their mouths to feed without using their teeth at all, instead filtering the food when passing water through their gills; as one species evolves into another, its teeth may become difficult to classify, exhibiting characteristics of both species. For example, teeth from Carcharocles auriculatus as it evolved into C. angustidens, are difficult to definitively identify as coming from either species. A referred to transition is the evolution of Isurus hastalis, the Extinct Giant Mako, into the Great White shark, Carcharodon carcharias. There exist teeth; these teeth, from Carcharodon sp. are characterised by the wider, flatter crowns of the Extinct Giant Mako. However, they exhibit partial, fading serrations, which are more pronounced near the root, disappear towards the tip of the tooth - serrations being found in Great Whites but not Extinct Giant Makos.
C. megalodon teeth are the largest of any shark, extinct or living, are among the most sought after types of shark teeth in the world. This shark lived during the late Oligocene epoch and Neogene period, about 28 to 1.5 million years ago, ranged to a maximum length of 60 ft. The smallest teeth are only 1.2 cm in height. The smaller teeth ranging from 3½" and 4½" are more common finds, while teeth over 5", 6", 7" are more rare; these teeth are in high demand by collectors and private investors, they can fetch steep prices according to their size and deterioration. The larger teeth can cost as much as 3,000 dollars. Shark teeth cannot be collected from just any type of rock. Any fossils, including fossil shark teeth, are preserved in sedimentary rocks after falling from their mouth; the sediment that the teeth were found in is used to help determine the age of the shark tooth due to the fossilization process. Shark teeth are most found between the Upper Cretaceous and Tertiary periods. Only after about 10,000 years will a shark tooth fossilize.
The teeth found are not white because they are covered with sediment from fossilization. The sediment prevents oxygen and bacteria from decaying the tooth. Fossilized shark teeth can be found in or near river bed banks, sand pits, beaches; these teeth are worn, because they were moved and redeposited in different areas before settling down. Other locations, yield perfect teeth that were hardly moved during the ages; these teeth are fragile, great care should be taken while excavating them. Phosphate pits, containing fossil bones and teeth, or kaolin pits, are ideal places to look for fossil shark teeth. One of the most notable phosphate mines is in Central Florida, Polk County, is known as Bone Valley. Most of the teeth found here range from 3 to 10 m
The tiger shark is a species of requiem shark and the only extant member of the genus Galeocerdo. It is a large macropredator, capable of attaining a length over 5 m. Populations are found in many tropical and temperate waters around central Pacific islands, its name derives from the dark stripes down its body, which resemble a tiger's pattern, but fade as the shark matures. The tiger shark is a solitary nocturnal hunter, it is notable for having the widest food spectrum of all sharks, with a range of prey that includes crustaceans, seals, squid, sea snakes and other smaller sharks. It has a reputation as a "garbage eater", consuming a variety of inedible, man-made objects that linger in its stomach. Though apex predators, tiger sharks are sometimes taken by groups of killer whales, it is considered a near threatened species due to fishing by humans. The tiger shark is second only to the great white in recorded fatal attacks on humans; the shark was first described by Peron and Lesueur in 1822, was given the name Squalus cuvier.
Müller and Henle in 1837 renamed it Galeocerdo tigrinus. The genus, Galeocerdo, is derived from the Greek galeos, which means shark, kerdo, the word for fox, it is colloquially called the man-eater shark. The tiger shark is a member of the order Carcharhiniformes, the most species-rich order of sharks, with more than 270 species including the small catsharks and hammerhead sharks. Members of this order are characterized by the presence of a nictitating membrane over the eyes, two dorsal fins, an anal fin, five gill slits, it is the largest member of the Carcharhinidae family referred to as requiem sharks. This family consists of slender but powerful mid- to large-sized sharks and includes some other well-known sharks, such as the blue shark, lemon shark, bull shark; the tiger shark attains a length of 3.25–4.25 m and weighs around 385–635 kg. It is dimorphic, with exceptionally large females measuring over 5 m, the largest males 4 m. Weights of large female tiger sharks can exceed 900 kg. One pregnant female caught off Australia measured 5.5 m long and weighed 1,524 kg.
Larger unconfirmed catches have been claimed. Some papers have accepted a record of an exceptional 7.4 m length for a tiger shark, but since this is far larger than any scientifically observed specimen, verification would be needed. Among the largest extant sharks, the tiger shark ranks in average size only behind the whale shark, the basking shark, the great white shark; some other species such as megamouth sharks, Pacific sleeper sharks, Greenland sharks, bluntnose sixgill sharks broadly overlap in size with the tiger shark, but as these species are comparatively poorly studied, whether their typical mature size matches that of the tiger shark is unclear. The great hammerhead, a member of the same taxonomic order as the tiger shark, has a similar or greater average body length, but is lighter and less bulky, with a maximum known weight of 580 kg. Tiger shark teeth are unique with sharp, pronounced serrations and an unmistakable sideways-pointing tip; such dentition has developed to slice through flesh and other tough substances such as turtle shells.
Like most sharks, its teeth are continually replaced by rows of new teeth throughout the shark's life. Relative to the shark's size, tiger shark teeth are shorter than those of a great white shark, but they are nearly as broad as the root as the great white's teeth and are arguably better suited to slicing through hard-surfaced prey. A tiger shark has long fins to provide lift as the shark maneuvers through water, while the long upper tail provides bursts of speed; the tiger shark swims using small body movements. Its high back and dorsal fin act as a pivot, allowing it to spin on its axis, though the shark's dorsal fins are distinctively close to its tail; the skin of a tiger shark can range from blue to light green with a white or light-yellow underbelly. The advantage of this is that when it is hunting for its prey, when prey looks at the shark from above, the shark will be camouflaged, since the water below is darker And when prey is below the shark and looks up, of course because of the sun, it is lighter so that the light underbelly will camouflage the shark.
This is known as countershading. Dark spots and stripes fade as the shark matures, its head is somewhat wedge-shaped, which makes it easy to turn to one side. They have small pits on the snout which hold electroreceptors called the ampullae of Lorenzini, which enable them to detect electric fields, including the weak electrical impulses generated by prey, which helps them to hunt. Tiger sharks have a sensory organ called a lateral line which extends on their flanks down most of the length of their sides; the primary role of this structure is to detect minute vibrations in the water. These adaptations detect hidden prey. Sharks do not have moveable upper or lower eyelids, but the tiger shark—among other sharks—has a nictitating membrane, a clear eyelid that can cover the eye. A reflective layer behind the tiger shark's retina, called the tapetum lucidum, allows light-sensing cells a second chance to capture photons of visible light; this enhances vision in low-li
A leaf is an organ of a vascular plant and is the principal lateral appendage of the stem. The leaves and stem together form the shoot. Leaves are collectively referred to as foliage, as in "autumn foliage". A leaf is a thin, dorsiventrally flattened organ borne above ground and specialized for photosynthesis. In most leaves, the primary photosynthetic tissue, the palisade mesophyll, is located on the upper side of the blade or lamina of the leaf but in some species, including the mature foliage of Eucalyptus, palisade mesophyll is present on both sides and the leaves are said to be isobilateral. Most leaves have distinct upper surface and lower surface that differ in colour, the number of stomata, the amount and structure of epicuticular wax and other features. Leaves can have many different shapes and textures; the broad, flat leaves with complex venation of flowering plants are known as megaphylls and the species that bear them, the majority, as broad-leaved or megaphyllous plants. In the clubmosses, with different evolutionary origins, the leaves are simple and are known as microphylls.
Some leaves, such as bulb scales, are not above ground. In many aquatic species the leaves are submerged in water. Succulent plants have thick juicy leaves, but some leaves are without major photosynthetic function and may be dead at maturity, as in some cataphylls and spines. Furthermore, several kinds of leaf-like structures found in vascular plants are not homologous with them. Examples include flattened plant stems called phylloclades and cladodes, flattened leaf stems called phyllodes which differ from leaves both in their structure and origin; some structures of non-vascular plants function much like leaves. Examples include the phyllids of liverworts. Leaves are the most important organs of most vascular plants. Green plants are autotrophic, meaning that they do not obtain food from other living things but instead create their own food by photosynthesis, they capture the energy in sunlight and use it to make simple sugars, such as glucose and sucrose, from carbon dioxide and water. The sugars are stored as starch, further processed by chemical synthesis into more complex organic molecules such as proteins or cellulose, the basic structural material in plant cell walls, or metabolised by cellular respiration to provide chemical energy to run cellular processes.
The leaves draw water from the ground in the transpiration stream through a vascular conducting system known as xylem and obtain carbon dioxide from the atmosphere by diffusion through openings called stomata in the outer covering layer of the leaf, while leaves are orientated to maximise their exposure to sunlight. Once sugar has been synthesized, it needs to be transported to areas of active growth such as the plant shoots and roots. Vascular plants transport sucrose in a special tissue called the phloem; the phloem and xylem are parallel to each other but the transport of materials is in opposite directions. Within the leaf these vascular systems branch to form veins which supply as much of the leaf as possible, ensuring that cells carrying out photosynthesis are close to the transportation system. Leaves are broad and thin, thereby maximising the surface area directly exposed to light and enabling the light to penetrate the tissues and reach the chloroplasts, thus promoting photosynthesis.
They are arranged on the plant so as to expose their surfaces to light as efficiently as possible without shading each other, but there are many exceptions and complications. For instance plants adapted to windy conditions may have pendent leaves, such as in many willows and eucalyptss; the flat, or laminar, shape maximises thermal contact with the surrounding air, promoting cooling. Functionally, in addition to carrying out photosynthesis, the leaf is the principal site of transpiration, providing the energy required to draw the transpiration stream up from the roots, guttation. Many gymnosperms have thin needle-like or scale-like leaves that can be advantageous in cold climates with frequent snow and frost; these are interpreted as reduced from megaphyllous leaves of their Devonian ancestors. Some leaf forms are adapted to modulate the amount of light they absorb to avoid or mitigate excessive heat, ultraviolet damage, or desiccation, or to sacrifice light-absorption efficiency in favour of protection from herbivory.
For xerophytes the major constraint drought. Some window plants such as Fenestraria species and some Haworthia species such as Haworthia tesselata and Haworthia truncata are examples of xerophytes. and Bulbine mesembryanthemoides. Leaves function to store chemical energy and water and may become specialised organs serving other functions, such as tendrils of peas and other legumes, the protective spines of cacti and the insect traps in carnivorous plants such as Nepenthes and Sarracenia. Leaves are the fundamental structural units from which cones are constructed in gymnosperms and from which flowers are constructed in flowering plants; the internal organisation of most kinds of leaves has evolved to maximise exposure of the photosynthetic organelles, the chloroplasts, to light and to increase the absorption of carbon dioxide while at the same time controlling water loss. Their surfaces are waterproofed by the plant cuticle and gas exchange between the mesophyll cells and the atmosphere is controlled by minute openings called stomata which open or close to regulate the rate exchange of carbon dioxide and water vapour into
A serrated blade is a type of blade used on saws and on some knives or scissors. It is known as a dentated, sawtooth, or toothed blade. A serrated blade has a cutting edge. By having less contact area than a smooth blade, the applied pressure at each point of contact is greater and the points of contact are at a sharper angle to the material being cut; this causes a cutting action that involves many small splits in the surface of the material being cut, which cumulatively serve to cut the material along the line of the blade. Cuts made with a serrated blade are less smooth and precise than cuts made with a smooth blade. Serrated blades can be more difficult to sharpen using a whetstone or rotary sharpener than a non-serrated, they can be sharpened with a diamond. Serrated blades tend to stay sharper longer than a similar straight edged blade. A serrated blade has a faster cut but a plain edge has a cleaner cut; some prefer a serrated blade on a pocket knife
Dianthus caryophyllus, the carnation or clove pink, is a species of Dianthus. It is native to the Mediterranean region but its exact range is unknown due to extensive cultivation for the last 2,000 years. Carnation cultivars with no fragrance are used by men as boutonnieres or "button holes." It is an herbaceous perennial plant growing up to 80 cm tall. The leaves are glaucous greyish green to slender, up to 15 cm long; the flowers are produced up to five together in a cyme. The fragrant, hermaphrodite flowers have a radial symmetry; the four to six surrounding the calyx, egg-shaped, sting-pointed scales leaves are only ¼ as long as the calyx tube. Carnations require well-drained, neutral to alkaline soil, full sun. Numerous cultivars have been selected for garden planting. Typical examples include'Gina Porto','Helen','Laced Romeo', and'Red Rocket', they are used for medical purposes, such as for upset fever. Their fragrance was used for vinegar, wine and salads. For the most part, carnations express love and distinction, though there are many variations dependent on color.
Along with the red rose, the red carnation can be used as a symbol of socialism and the labour movement, has been used in demonstrations on International Workers' Day. In Portugal, bright red carnations were used when in 1974 the authoritarian Estado Novo regime was overthrown. Light red carnations represent admiration, while dark red denote deep affection. White carnations represent pure love and good luck, while striped carnations symbolise regret that a love cannot be shared. White carnations, in the Netherlands are associated with HRH prince Bernhard, he wore one during World War II and in a gesture of defiance some of the Dutch population took up this gesture. After the war the white carnation became a sign of the Prince and remembrance of the resistance. Purple carnations indicate capriciousness. In France, it is a traditional funeral flower, given in condolence for the death of a loved one. According to a Christian legend, carnations first appeared on Earth; the Virgin Mary shed tears at Jesus' plight, carnations sprang up from where her tears fell.
Thus the pink carnation became the symbol of a mother's undying love. Carnation is the birth flower for those born in the month of January; the formal name for carnation, comes from Greek for "heavenly flower", or the flower of Jove. Carnations are worn on special occasions Mother's Day and weddings. In 1907, Anna Jarvis chose a carnation as the emblem of Mother's Day because it was her mother's favourite flower; this tradition is now observed in the United States and Canada on the second Sunday in May. Ann Jarvis chose the white carnation; this meaning has evolved over time, now a red carnation may be worn if one's mother is alive, a white one if she has died. In Korea, carnations express admiration and gratitude. Red and pink carnations are worn on Parents Day. Sometimes, parents wear a corsage of carnation on their left chest on Parents Day. Carnations are worn on Teachers Day. Red carnations are worn on May Day as a symbol of socialism and the labour movement in some countries, such as Austria and successor countries of the former Yugoslavia.
The red carnation is the symbol of the Portuguese Carnation Revolution. Green carnations were famously worn by the Irish writer Oscar Wilde; the green carnation thence became a symbol of homosexuality in the early 20th century through the book The Green Carnation and Noël Coward's song, "We All Wear a Green Carnation" in his operetta, Bitter Sweet. In communist Czechoslovakia and in Poland in times of the People's Republic of Poland, carnations were traditionally given to women on the celebrated Women's Day, together with commodities that were difficult to obtain due to the countries' communist system, such as tights, towels and coffee. At the University of Oxford, carnations are traditionally worn to all examinations. One story explaining this tradition relates that a white carnation was kept in a red inkpot between exams, so by the last exam it was red. Carnations are the traditional first wedding anniversary flower; the carnation is the national flower of Spain and Slovenia, the provincial flower of the autonomous community of the Balearic Islands.
The state flower of Ohio is a scarlet carnation, introduced to the state by Levi L. Lamborn; the choice was made to honor William McKinley, Ohio Governor and U. S. President, assassinated in 1901, wore a scarlet carnation on his lapel. Carnations do not produce the pigment delphinidin, thus a blue carnation cannot occur by natural selection or be created by traditional plant breeding, it shares this characteristic with other sold flowers like roses, tulips and gerberas. Around 1996 a company, used genetic engineering to extract certain genes from petunia and snapdragon flowers to produce a blue-mauve carnation, commercialize
The Brogue is a style of low-heeled shoe or boot traditionally characterised by multiple-piece, sturdy leather uppers with decorative perforations and serration along the pieces' visible edges. Brogues were traditionally considered to be outdoor or country footwear not otherwise appropriate for casual or business occasions, but brogues are now considered appropriate in most contexts. Brogues are most found in one of four toe cap styles and four closure styles. Today, in addition to their typical form of sturdy leather shoes or boots, brogues may take the form of business dress shoes, high-heeled women's shoes, or any other shoe form that utilises or evokes the multi-piece construction and perforated, serrated piece edges characteristic of brogues. Modern brogues trace their roots to a rudimentary shoe originating in Ireland and Scotland, constructed using untanned hide. Modern brogues feature decorative perforations; these are said to stem from the original Irish brogues as well from holes intended to allow water to drain from the shoes when the wearer crossed wet terrain such as a bog.
However, contemporary descriptions of the original brogues do not mention such holes. The word "brogue" came into English in the late sixteenth century, it comes from the Gaelic bróg, bròg "shoe", from the Old Norse "brók" meaning "leg covering". The Scots word brogue is used to denote a bradawl or boring tool as well as the action of piercing with such a tool; the word "brogue" was first used to describe a form of outdoor, country walking shoe in the early twentieth century traditionally worn by men. At that time the brogue was not considered to be appropriate for other occasions, social or business. Over time perceptions have changed and brogues are now considered appropriate in most contexts, including business. Brogues continue to be most common as leather dress and casual shoes and boots, but can be found in many other forms including canvas and leather sneakers and high-heeled women's shoes. Brogues are most found in one of four toe-cap styles and four closure styles. Most offered as a leather dress shoe, brogues may come in the form of boots, canvas or leather sneakers or any other shoe type that includes or evokes the multi-piece construction and perforated, serrated edges characteristic of brogues.
Here is an example of derby style brogue shoes for men. Brogue styles are determined by the shape of the toe cap and include the available full brogue, semi-brogue and quarter brogue styles, may be found in the less common longwing brogue style. Full brogues are characterised by a pointed toe cap with extensions that run along both sides of the toe, terminating near the ball of the foot. Viewed from the top, this toe cap style is "W" shaped and looks similar to a bird with extended wings, explaining the style name "wingtips", used in the United States; the toe cap of a full brogue is both perforated and serrated along its edges and includes additional decorative perforations in the center of the toe cap. A shoe with a wingtip-style toecap but no perforations is known as an "austerity brogue", while a plain-toe shoe with wingtip-style perforations is a "blind brogue". Spectator shoes are full brogue Oxfords constructed from two contrasting colours having the toe and heel cap and sometimes the lace panels in a darker color than the main body of the shoe.
Common color combinations include a white shoe body with either black or tan caps, but other colours can be used. The ghillie style of full brogue has no tongue, to facilitate drying, long laces that wrap around the leg above the ankle and tie below the calf to facilitate keeping the tie clear of mud. Despite the functional aspects of their design, ghillie brogues are most seen as a component of traditional, formal Scottish dress and are worn for social occasions. Semi-brogues are characterised by a toe cap with decorative perforations and serration along the cap's edge and includes additional decorative perforations in the center of the toe cap; the half brogue was first designed and produced by John Lobb Ltd. as an Oxford in 1937 in an effort to offer his customers a shoe more stylish than a plain oxford, yet not as bold as a full brogue. Quarter brogues are characterised by a cap toe with decorative perforations and serrations along the cap's edge, unlike semi-brogues, quarter brogues have no decorative perforations in the center of the toe cap.
Quarter brogues are more formal than full brogues. Longwing brogues are Derby style shoes characterised by a pointed toe cap with wings that extend the full length of the shoe, meeting at a center seam at the heel. Longwing Derby brogues were most popular in the US during the 1970s, although the popularity of this style has decreased, it remains available. Closure style is not a defining characteristic of the brogue and therefore brogues can be found in a variety of closure styles. Brogues are available in laced Oxford, Derby or ghillie styles, but can be found as buckle and monk strap shoes and slip-on shoes with or without elastic closures. Oxford shoe Derby shoe Ghillies Monk sh