Eye
Eyes are organs of the visual system. They provide organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes convert it into electro-chemical impulses in neurons. In higher organisms, the eye is a complex optical system which collects light from the surrounding environment, regulates its intensity through a diaphragm, focuses it through an adjustable assembly of lenses to form an image, converts this image into a set of electrical signals, transmits these signals to the brain through complex neural pathways that connect the eye via the optic nerve to the visual cortex and other areas of the brain. Eyes with resolving power have come in ten fundamentally different forms, 96% of animal species possess a complex optical system. Image-resolving eyes are present in molluscs and arthropods; the simplest "eyes", such as those in microorganisms, do nothing but detect whether the surroundings are light or dark, sufficient for the entrainment of circadian rhythms.
From more complex eyes, retinal photosensitive ganglion cells send signals along the retinohypothalamic tract to the suprachiasmatic nuclei to effect circadian adjustment and to the pretectal area to control the pupillary light reflex. Complex eyes can distinguish colours; the visual fields of many organisms predators, involve large areas of binocular vision to improve depth perception. In other organisms, eyes are located so as to maximise the field of view, such as in rabbits and horses, which have monocular vision; the first proto-eyes evolved among animals 600 million years ago about the time of the Cambrian explosion. The last common ancestor of animals possessed the biochemical toolkit necessary for vision, more advanced eyes have evolved in 96% of animal species in six of the ~35 main phyla. In most vertebrates and some molluscs, the eye works by allowing light to enter and project onto a light-sensitive panel of cells, known as the retina, at the rear of the eye; the cone cells and the rod cells in the retina detect and convert light into neural signals for vision.
The visual signals are transmitted to the brain via the optic nerve. Such eyes are roughly spherical, filled with a transparent gel-like substance called the vitreous humour, with a focusing lens and an iris; the eyes of most cephalopods, fish and snakes have fixed lens shapes, focusing vision is achieved by telescoping the lens—similar to how a camera focuses. Compound eyes are found among the arthropods and are composed of many simple facets which, depending on the details of anatomy, may give either a single pixelated image or multiple images, per eye; each sensor has its own photosensitive cell. Some eyes have up to 28,000 such sensors, which are arranged hexagonally, which can give a full 360° field of vision. Compound eyes are sensitive to motion; some arthropods, including many Strepsiptera, have compound eyes of only a few facets, each with a retina capable of creating an image, creating vision. With each eye viewing a different thing, a fused image from all the eyes is produced in the brain, providing different, high-resolution images.
Possessing detailed hyperspectral colour vision, the Mantis shrimp has been reported to have the world's most complex colour vision system. Trilobites, which are now extinct, had unique compound eyes, they used clear calcite crystals to form the lenses of their eyes. In this, they differ from most other arthropods; the number of lenses in such an eye varied, however: some trilobites had only one, some had thousands of lenses in one eye. In contrast to compound eyes, simple eyes are those. For example, jumping spiders have a large pair of simple eyes with a narrow field of view, supported by an array of other, smaller eyes for peripheral vision; some insect larvae, like caterpillars, have a different type of simple eye which provides only a rough image, but can possess resolving powers of 4 degrees of arc, be polarization sensitive and capable of increasing its absolute sensitivity at night by a factor of 1,000 or more. Some of the simplest eyes, called ocelli, can be found in animals like some of the snails, which cannot "see" in the normal sense.
They do have photosensitive cells, but no lens and no other means of projecting an image onto these cells. They can no more; this enables snails to keep out of direct sunlight. In organisms dwelling near deep-sea vents, compound eyes have been secondarily simplified and adapted to spot the infra-red light produced by the hot vents—in this way the bearers can spot hot springs and avoid being boiled alive. There are ten different eye layouts—indeed every technological method of capturing an optical image used by human beings, with the exceptions of zoom and Fresnel lenses, occur in nature. Eye types can be categorised into "simple eyes", with one concave photoreceptive surface, "compound eyes", which comprise a number of individual lenses laid out on a convex surface. Note that "simple" does not imply a reduced level of complexity or acuity. Indeed, any eye type can be adapted for any behaviour or environment; the only limitations specific to eye types are that of resolution—the physics of compound eyes prevents them from achieving a resolution better than 1°.
Superposition eyes can achieve greater sensitivity than apposition eyes, so are better suited to
Mackerel
Mackerel is a common name applied to a number of different species of pelagic fish from the family Scombridae. They are found in both temperate and tropical seas living along the coast or offshore in the oceanic environment. Mackerel species have vertical stripes on their backs and forked tails. Many are restricted in their distribution ranges and live in separate populations or fish stocks based on geography; some stocks migrate in large schools along the coast to suitable spawning grounds, where they spawn in shallow waters. After spawning they return the way they came in smaller schools to suitable feeding grounds near an area of upwelling. From there they may spend the winter in relative inactivity. Other stocks migrate across oceans. Smaller mackerel are forage fish including larger mackerel and Atlantic cod. Flocks of seabirds, dolphins and schools of larger fish such as tuna and marlin follow mackerel schools and attack them in sophisticated and cooperative ways. Mackerel flesh is intensively harvested by humans.
In 2009, over 5 million tons were landed by commercial fishermen. Sport fishermen value the fighting abilities of the king mackerel. Over 30 different species, principally belonging to the family Scombridae, are referred to as mackerel; the term "mackerel" means "marked" or "spotted", derives from the Old French maquerel, from around 1300, meaning a pimp or procurer. The connection is not altogether clear, but mackerel spawn enthusiastically in shoals near the coast, medieval ideas on animal procreation were creative. About 21 species in the family Scombridae are called mackerel; the type species for the scombroid mackerel is the Atlantic mackerel, Scomber scombrus. Until Atlantic chub mackerel and Indo-Pacific chub mackerel were thought to be subspecies of the same species. In 1999, Collette established, on molecular and morphological considerations, that these are separate species. Mackerel are smaller with shorter lifecycles than their close relatives, the tuna, which are members of the same family.
The true mackerels belong to the tribe Scombrini. The tribe consists of each belonging to one of two genera: Scomber or Rastrelliger; the Spanish mackerels belong to the tribe Scomberomorini, the "sister tribe" of the true mackerels. This tribe consists of 21 species in all—18 of those are classified into the genus Scomberomorus, two into Grammatorcynus, a single species into the monotypic genus Acanthocybium. In addition, a number of species with mackerel-like characteristics in the families Carangidae and Gempylidae are referred to as mackerel; some confusion had occurred between the Pacific jack mackerel and the harvested Chilean jack mackerel. These are now recognised as separate species; the term "mackerel" is used as a modifier in the common names of other fish, sometimes indicating the fish has vertical stripes similar to a scombroid mackerel: Mackerel icefish—Champsocephalus gunnari Mackerel pike—Cololabis saira Mackerel scad—Decapterus macarellus Mackerel shark—several species Shortfin mako shark—Isurus oxyrinchus Mackerel tuna—Euthynnus affinis Mackerel tail goldfish—Carassius auratusBy extension, the term is applied to other species such as the mackerel tabby cat, to inanimate objects such as the altocumulus mackerel sky cloud formation.
Most mackerel belong to the family Scombridae, which includes tuna and bonito. Mackerel are much smaller and slimmer than tuna, though in other respects, they share many common characteristics, their scales, if present at all, are small. Like tuna and bonito, mackerel are voracious feeders, are swift and manoeuvrable swimmers, able to streamline themselves by retracting their fins into grooves on their bodies. Like other scombroids, their bodies are cylindrical with numerous finlets on the dorsal and ventral sides behind the dorsal and anal fins, but unlike the deep-bodied tuna, they are slim; the type species for scombroid mackerels is the Atlantic mackerel, Scomber scombrus. These fish are iridescent blue-green above with a silvery underbelly and 200-30 near-vertical wavy black stripes running across their upper bodies; the prominent stripes on the back of mackerels are there to provide camouflage against broken backgrounds. That is not the case, because mackerel live in midwater pelagic environments which have no background.
However, fish have an optokinetic reflex in their visual systems that can be sensitive to moving stripes. For fish to school efficiently, they need feedback mechanisms that help them align themselves with adjacent fish, match their speed; the stripes on neighbouring fish provide "schooling marks", which signal changes in relative position. A layer of thin, reflecting platelets is seen on some of the mackerel stripes. In 1998, E J Denton and D M Rowe argued that these platelets transmit additional information to other fish about how a given fish moves; as the orientation of the fish changes relative to another fish, the amount of light reflected to the second fish by this layer changes. This sensitivity to orientation gives the mackerel "considerable advantages in being able to react while schooling and feeding."Mackerel range in size from small forage fish to larger game fish. Coastal mackerel tend to be small; the king mackerel is an example of a larger mackerel. Most fish are cold-blooded. Certain species of fish maintain elevated body temperatures.
Endothermic bony fishes are all in the suborder Scombroidei and include the butterfly mackerel, a species of primiti
William John Swainson
William John Swainson FLS, FRS, was an English ornithologist, conchologist and artist. Swainson was born in Dover Place, St Mary Newington, the eldest son of John Timothy Swainson the Second, an original fellow of the Linnean Society, he was cousin of the amateur botanist Isaac Swainson. His father's family originated in Lancashire, both grandfather and father held high posts in Her Majesty's Customs, the father becoming Collector at Liverpool. William, whose formal education was curtailed because of an impediment in his speech, joined the Liverpool Customs as a junior clerk at the age of 14, he joined the Army Commissariat and toured Malta and Sicily He studied the ichthyology of western Sicily and in 1815, was forced by ill health to return to England where he subsequently retired on half pay. William followed in his father's footsteps to become a fellow of the Linnean Society in 1815. In 1806 he accompanied the English explorer Henry Koster to Brazil. Koster had become famous for his book Travels in Brazil.
There he met Dr Grigori Ivanovitch Langsdorff an explorer of Brazil, Russian Consul General. They did not spend a long time on shore because of a revolution, but Swainson returned to England in 1818 in his words "a bee loaded with honey", with a collection of over 20,000 insects, 1,200 species of plants, drawings of 120 species of fish, about 760 bird skins; as with many Victorian scientists, Swainson was a member of many learned societies, including the Wernerian Society of Edinburgh. He was elected a fellow of the Royal Society after his return from Brazil on 14 December 1820, married his first wife Mary Parkes in 1823, with whom he had four sons and a daughter, his wife Mary died in 1835. Swainson remarried in 1840 to Ann Grasby, emigrated to New Zealand in 1841, their daughter, Edith Stanway Swainson, married Arthur Halcombe in 1863. Swainson was involved in property management and natural history-related publications from 1841 to 1855, forestry-related investigations in Tasmania, New South Wales, Victoria from 1851 to 1853.
Swainson died at Fern Grove, Lower Hutt, New Zealand, on 6 December 1855. Swainson was at times quite critical of the works of others and in life, others in turn became quite critical of him. Apart from the common and scientific names of many species, it is for the quality of his illustrations that he is best remembered, his friend William Elford Leach, head of zoology at the British Museum, encouraged him to experiment with lithography for his book Zoological Illustrations. Swainson became the first illustrator and naturalist to use lithography, a cheap means of reproduction and did not require an engraver, he began publishing many illustrated works serially. Subscribers received and paid for fascicles, small sections of the books, as they came out, so that the cash flow was constant and could be reinvested in the preparation of subsequent parts; as book orders arrived, the monochrome lithographs were hand-coloured, according to colour reference images, known as ‘pattern plates’, which were produced by Swainson himself.
It was his early adoption of this new technology and his natural skill of illustration that in large part led to his fame. When in March 1822 Leach was forced to resign from the British Museum due to ill health, Swainson applied to replace him, but the post was given to John George Children. Soon after his first marriage in 1823, Swainson visited Paris and formed friendships with Georges Cuvier, Étienne Geoffroy Saint-Hilaire, other eminent French naturalists. Upon his return to London, he was employed by Messrs. Longman as editor for the natural history departments of Lardner's Cabinet Cyclopedia. Swainson continued with his writing, the most influential of, the second volume of Fauna Boreali-Americana, which he wrote with John Richardson; this series was the first illustrated zoological study to be funded in part by the British government. He produced a second series of Zoological Illustrations, three volumes of William Jardine's Naturalist's Library, eleven volumes of Lardner's Cabinet Cyclopedia.
In 1819 William Sharp Macleay had published his ideas of the Quinarian system of biological classification, Swainson soon became a noted and outspoken proponent. The Quinarian System fell out of favour, giving way to the rising popularity of the geographical theory of Hugh Edwin Strickland. Swainson was overworked by Dionysius Lardner, the publisher of the Cabinet Cyclopaedia and both Swainson and Macleay were derided for their support of the Quinarian system. Both proponents left Britain. An American visiting Australasia in the 1850s heard to his surprise that both Macleay and Swainson were living there, imagined that they had been exiled to the Antipodes'for the great crime of burdening zoology with a false though much laboured theory which has thrown so much confusion into the subject of its classification and philosophical study'. In 1839 he became a member of the committee of the New Zealand Company and of the Church of England committee for the appointment of a bishop to New Zealand, bought land in Wellington, gave up scientific literary work.
He married his second wife, Anne Grasby, in 1840. He was the first Fellow of the Royal Society to move to New Zealand, he was made an honorary Fellow of the Royal Society of Tasmania. Together with most of his chi
Animal
Animals are multicellular eukaryotic organisms that form the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, grow from a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from 8.5 millionths of a metre to 33.6 metres and have complex interactions with each other and their environments, forming intricate food webs. The category includes humans, but in colloquial use the term animal refers only to non-human animals; the study of non-human animals is known as zoology. Most living animal species are in the Bilateria, a clade whose members have a bilaterally symmetric body plan; the Bilateria include the protostomes—in which many groups of invertebrates are found, such as nematodes and molluscs—and the deuterostomes, containing the echinoderms and chordates.
Life forms interpreted. Many modern animal phyla became established in the fossil record as marine species during the Cambrian explosion which began around 542 million years ago. 6,331 groups of genes common to all living animals have been identified. Aristotle divided animals into those with those without. Carl Linnaeus created the first hierarchical biological classification for animals in 1758 with his Systema Naturae, which Jean-Baptiste Lamarck expanded into 14 phyla by 1809. In 1874, Ernst Haeckel divided the animal kingdom into the multicellular Metazoa and the Protozoa, single-celled organisms no longer considered animals. In modern times, the biological classification of animals relies on advanced techniques, such as molecular phylogenetics, which are effective at demonstrating the evolutionary relationships between animal taxa. Humans make use of many other animal species for food, including meat and eggs. Dogs have been used in hunting, while many aquatic animals are hunted for sport.
Non-human animals have appeared in art from the earliest times and are featured in mythology and religion. The word "animal" comes from the Latin animalis, having soul or living being; the biological definition includes all members of the kingdom Animalia. In colloquial usage, as a consequence of anthropocentrism, the term animal is sometimes used nonscientifically to refer only to non-human animals. Animals have several characteristics. Animals are eukaryotic and multicellular, unlike bacteria, which are prokaryotic, unlike protists, which are eukaryotic but unicellular. Unlike plants and algae, which produce their own nutrients animals are heterotrophic, feeding on organic material and digesting it internally. With few exceptions, animals breathe oxygen and respire aerobically. All animals are motile during at least part of their life cycle, but some animals, such as sponges, corals and barnacles become sessile; the blastula is a stage in embryonic development, unique to most animals, allowing cells to be differentiated into specialised tissues and organs.
All animals are composed of cells, surrounded by a characteristic extracellular matrix composed of collagen and elastic glycoproteins. During development, the animal extracellular matrix forms a flexible framework upon which cells can move about and be reorganised, making the formation of complex structures possible; this may be calcified, forming structures such as shells and spicules. In contrast, the cells of other multicellular organisms are held in place by cell walls, so develop by progressive growth. Animal cells uniquely possess the cell junctions called tight junctions, gap junctions, desmosomes. With few exceptions—in particular, the sponges and placozoans—animal bodies are differentiated into tissues; these include muscles, which enable locomotion, nerve tissues, which transmit signals and coordinate the body. There is an internal digestive chamber with either one opening or two openings. Nearly all animals make use of some form of sexual reproduction, they produce haploid gametes by meiosis.
These fuse to form zygotes, which develop via mitosis into a hollow sphere, called a blastula. In sponges, blastula larvae swim to a new location, attach to the seabed, develop into a new sponge. In most other groups, the blastula undergoes more complicated rearrangement, it first invaginates to form a gastrula with a digestive chamber and two separate germ layers, an external ectoderm and an internal endoderm. In most cases, a third germ layer, the mesoderm develops between them; these germ layers differentiate to form tissues and organs. Repeated instances of mating with a close relative during sexual reproduction leads to inbreeding depression within a population due to the increased prevalence of harmful recessive traits. Animals have evolved numerous mechanisms for avoiding close inbreeding. In some species, such as the splendid fairywren, females benefit by mating with multiple males, thus producing more offspring of higher genetic quality; some animals are capable of asexual reproduction, which results
Pelagic fish
Pelagic fish live in the pelagic zone of ocean or lake waters – being neither close to the bottom nor near the shore – in contrast with demersal fish, which do live on or near the bottom, reef fish, which are associated with coral reefs. The marine pelagic environment is the largest aquatic habitat on Earth, occupying 1,370 million cubic kilometres, is the habitat for 11% of known fish species; the oceans have a mean depth of 4000 metres. About 98% of the total water volume is below 100 metres, 75% is below 1,000 metres. Marine pelagic fish can be divided into oceanic pelagic fish. Coastal fish inhabit the shallow and sunlit waters above the continental shelf, while oceanic fish inhabit the vast and deep waters beyond the continental shelf. Pelagic fish range in size from small coastal forage fish, such as herrings and sardines, to large apex predator oceanic fishes, such as bluefin tuna and oceanic sharks, they are agile swimmers with streamlined bodies, capable of sustained cruising on long-distance migrations.
Many pelagic fish swim in schools weighing hundreds of tonnes. Others are solitary, like the large ocean sunfish weighing over 500 kilograms, which sometimes drift passively with ocean currents, eating jellyfish. Epipelagic fish inhabit the epipelagic zone; the epipelagic zone is the water from the surface of the sea down to 200 metres. It is referred to as the surface waters or the sunlit zone, includes the photic zone; the photic zone is defined as the surface waters down to the point where the sunlight has attenuated to 1% of the surface value. This depth depends on how turbid the water is, but in clear water can extend to 200 metres, coinciding with the epipelagic zone; the photic zone has sufficient light for phytoplankton to photosynthese. The epipelagic zone is vast, is the home for most pelagic fish; the zone is well lit so visual predators can use their eyesight, is well mixed and oxygenated from wave action, can be a good habitat for algae to grow. However, it is an featureless habitat.
This lack of habitat diversity results in a lack of species diversity, so the zone supports less than 2% of the world's known fish species. Much of the zone lacks nutrients for supporting fish, so epipelagic fish tend to be found in coastal water above the continental shelves, where land runoff can provide nutrients, or in those parts of the ocean where upwelling moves nutrients into the area. Epipelagic fish can be broadly divided into small forage fish and larger predator fish which feed on them. Forage fish school and filter feed on plankton. Most epipelagic fish have streamlined bodies capable of sustained cruising on migrations. In general and forage fish share the same morphological features. Predator fish are fusiform with large mouths, smooth bodies, forked tails. Many use vision to prey on smaller fish, while others filter feed on plankton. Most epipelagic predator fish and their smaller prey fish are countershaded with silvery colours which reduce visibility by scattering incoming light.
The silvering is achieved with reflective fish scales. This can give an effect of transparency. At medium depths at sea, light comes from above, so a mirror oriented vertically makes animals such as fish invisible from the side. In the shallower epipelagic waters, the mirrors must reflect a mixture of wavelengths, the fish accordingly has crystal stacks with a range of different spacings. A further complication for fish with bodies that are rounded in cross-section is that the mirrors would be ineffective if laid flat on the skin, as they would fail to reflect horizontally; the overall mirror effect is achieved with all oriented vertically. Though the number of species is limited, epipelagic fishes are abundant. What they lack in diversity they make up in numbers. Forage fish occur in huge numbers, large fish that prey on them are sought after as premier food fish; as a group, epipelagic fishes form the most valuable fisheries in the world. Many forage fish are facultative predators that can pick individual copepods or fish larvae out of the water column, change to filter feeding on phytoplankton when energetically that gives better results.
Filter feeding fish use long fine gill rakers to strain small organisms from the water column. Some of the largest epipelagic fishes, such as the basking shark and whale shark, are filter feeders, so are some of the smallest, such as adult sprats and anchovies. Ocean waters that are exceptionally clear contain little food. Areas of high productivity tend to be somewhat turbid from plankton blooms; these attract the filter feeding plankton eaters. Tuna fishing tends to be optimum when water turbidity, measured by the maximum depth a secchi disc can be seen during a sunny day, is 15 to 35 metres. Epipelagic fish are fascinated with floating objects, they aggregate in considerable numbers around objects such as drifting flotsam, rafts and floating seaweed. The objects appear to provide a "visual stimulus in an optical void". Floating objects can offer refuge for juvenile fish from predators. An abundance of drifting seaweed or jellyfish can result in significant increases in the survival rates of some juvenile species.
Many coastal juveniles use seaweed for the shelter and the food, available from invertebrates and other fish associated with it. Drifting seaweed the pelagic Sargassum, provide a niche habitat with its own shelter and food, supports its own unique fauna, such as the sargassum fish. One study, off Florida, found 54 species from 23 families living in flotsam from Sargassum m
Cretaceous
The Cretaceous is a geologic period and system that spans 79 million years from the end of the Jurassic Period 145 million years ago to the beginning of the Paleogene Period 66 mya. It is the last period of the Mesozoic Era, the longest period of the Phanerozoic Eon; the Cretaceous Period is abbreviated K, for its German translation Kreide. The Cretaceous was a period with a warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas; these oceans and seas were populated with now-extinct marine reptiles and rudists, while dinosaurs continued to dominate on land. During this time, new groups of mammals and birds, as well as flowering plants, appeared; the Cretaceous ended with the Cretaceous–Paleogene extinction event, a large mass extinction in which many groups, including non-avian dinosaurs and large marine reptiles died out. The end of the Cretaceous is defined by the abrupt Cretaceous–Paleogene boundary, a geologic signature associated with the mass extinction which lies between the Mesozoic and Cenozoic eras.
The Cretaceous as a separate period was first defined by Belgian geologist Jean d'Omalius d'Halloy in 1822, using strata in the Paris Basin and named for the extensive beds of chalk, found in the upper Cretaceous of Western Europe. The name Cretaceous was derived from Latin creta; the Cretaceous is divided into Early and Late Cretaceous epochs, or Lower and Upper Cretaceous series. In older literature the Cretaceous is sometimes divided into three series: Neocomian and Senonian. A subdivision in eleven stages, all originating from European stratigraphy, is now used worldwide. In many parts of the world, alternative local subdivisions are still in use; as with other older geologic periods, the rock beds of the Cretaceous are well identified but the exact age of the system's base is uncertain by a few million years. No great extinction or burst of diversity separates the Cretaceous from the Jurassic. However, the top of the system is defined, being placed at an iridium-rich layer found worldwide, believed to be associated with the Chicxulub impact crater, with its boundaries circumscribing parts of the Yucatán Peninsula and into the Gulf of Mexico.
This layer has been dated at 66.043 Ma. A 140 Ma age for the Jurassic-Cretaceous boundary instead of the accepted 145 Ma was proposed in 2014 based on a stratigraphic study of Vaca Muerta Formation in Neuquén Basin, Argentina. Víctor Ramos, one of the authors of the study proposing the 140 Ma boundary age sees the study as a "first step" toward formally changing the age in the International Union of Geological Sciences. From youngest to oldest, the subdivisions of the Cretaceous period are: Late Cretaceous Maastrichtian – Campanian – Santonian – Coniacian – Turonian – Cenomanian – Early Cretaceous Albian – Aptian – Barremian – Hauterivian – Valanginian – Berriasian – The high sea level and warm climate of the Cretaceous meant large areas of the continents were covered by warm, shallow seas, providing habitat for many marine organisms; the Cretaceous was named for the extensive chalk deposits of this age in Europe, but in many parts of the world, the deposits from the Cretaceous are of marine limestone, a rock type, formed under warm, shallow marine circumstances.
Due to the high sea level, there was extensive space for such sedimentation. Because of the young age and great thickness of the system, Cretaceous rocks are evident in many areas worldwide. Chalk is a rock type characteristic for the Cretaceous, it consists of coccoliths, microscopically small calcite skeletons of coccolithophores, a type of algae that prospered in the Cretaceous seas. In northwestern Europe, chalk deposits from the Upper Cretaceous are characteristic for the Chalk Group, which forms the white cliffs of Dover on the south coast of England and similar cliffs on the French Normandian coast; the group is found in England, northern France, the low countries, northern Germany, Denmark and in the subsurface of the southern part of the North Sea. Chalk is not consolidated and the Chalk Group still consists of loose sediments in many places; the group has other limestones and arenites. Among the fossils it contains are sea urchins, belemnites and sea reptiles such as Mosasaurus. In southern Europe, the Cretaceous is a marine system consisting of competent limestone beds or incompetent marls.
Because the Alpine mountain chains did not yet exist in the Cretaceous, these deposits formed on the southern edge of the European continental shelf, at the margin of the Tethys Ocean. Stagnation of deep sea currents in middle Cretaceous times caused anoxic conditions in the sea water leaving the deposited organic matter undecomposed. Half the worlds petroleum reserves were laid down at this time in the anoxic conditions of what would become the Persian Gulf and the Gulf of Mexico. In many places around the world, dark anoxic shales were formed during this interval; these shales are an important source rock for oil and gas, for example in the subsurface of the North Sea. During th
Carl Linnaeus
Carl Linnaeus known after his ennoblement as Carl von Linné, was a Swedish botanist and zoologist who formalised binomial nomenclature, the modern system of naming organisms. He is known as the "father of modern taxonomy". Many of his writings were in Latin, his name is rendered in Latin as Carolus Linnæus. Linnaeus was born in the countryside of Småland in southern Sweden, he received most of his higher education at Uppsala University and began giving lectures in botany there in 1730. He lived abroad between 1735 and 1738, where he studied and published the first edition of his Systema Naturae in the Netherlands, he returned to Sweden where he became professor of medicine and botany at Uppsala. In the 1740s, he was sent on several journeys through Sweden to find and classify plants and animals. In the 1750s and 1760s, he continued to collect and classify animals and minerals, while publishing several volumes, he was one of the most acclaimed scientists in Europe at the time of his death. Philosopher Jean-Jacques Rousseau sent him the message: "Tell him I know no greater man on earth."
Johann Wolfgang von Goethe wrote: "With the exception of Shakespeare and Spinoza, I know no one among the no longer living who has influenced me more strongly." Swedish author August Strindberg wrote: "Linnaeus was in reality a poet who happened to become a naturalist." Linnaeus has been called Princeps botanicorum and "The Pliny of the North". He is considered as one of the founders of modern ecology. In botany and zoology, the abbreviation L. is used to indicate Linnaeus as the authority for a species' name. In older publications, the abbreviation "Linn." is found. Linnaeus's remains comprise the type specimen for the species Homo sapiens following the International Code of Zoological Nomenclature, since the sole specimen that he is known to have examined was himself. Linnaeus was born in the village of Råshult in Småland, Sweden, on 23 May 1707, he was the first child of Christina Brodersonia. His siblings were Anna Maria Linnæa, Sofia Juliana Linnæa, Samuel Linnæus, Emerentia Linnæa, his father taught him Latin as a small child.
One of a long line of peasants and priests, Nils was an amateur botanist, a Lutheran minister, the curate of the small village of Stenbrohult in Småland. Christina was the daughter of the rector of Samuel Brodersonius. A year after Linnaeus's birth, his grandfather Samuel Brodersonius died, his father Nils became the rector of Stenbrohult; the family moved into the rectory from the curate's house. In his early years, Linnaeus seemed to have a liking for plants, flowers in particular. Whenever he was upset, he was given a flower, which calmed him. Nils spent much time in his garden and showed flowers to Linnaeus and told him their names. Soon Linnaeus was given his own patch of earth. Carl's father was the first in his ancestry to adopt a permanent surname. Before that, ancestors had used the patronymic naming system of Scandinavian countries: his father was named Ingemarsson after his father Ingemar Bengtsson; when Nils was admitted to the University of Lund, he had to take on a family name. He adopted the Latinate name Linnæus after a giant linden tree, lind in Swedish, that grew on the family homestead.
This name was spelled with the æ ligature. When Carl was born, he was named Carl Linnæus, with his father's family name; the son always spelled it with the æ ligature, both in handwritten documents and in publications. Carl's patronymic would have been Nilsson, as in Carl Nilsson Linnæus. Linnaeus's father began teaching him basic Latin and geography at an early age; when Linnaeus was seven, Nils decided to hire a tutor for him. The parents picked a son of a local yeoman. Linnaeus did not like him, writing in his autobiography that Telander "was better calculated to extinguish a child's talents than develop them". Two years after his tutoring had begun, he was sent to the Lower Grammar School at Växjö in 1717. Linnaeus studied going to the countryside to look for plants, he reached the last year of the Lower School when he was fifteen, taught by the headmaster, Daniel Lannerus, interested in botany. Lannerus gave him the run of his garden, he introduced him to Johan Rothman, the state doctor of Småland and a teacher at Katedralskolan in Växjö.
A botanist, Rothman broadened Linnaeus's interest in botany and helped him develop an interest in medicine. By the age of 17, Linnaeus had become well acquainted with the existing botanical literature, he remarks in his journal that he "read day and night, knowing like the back of my hand, Arvidh Månsson's Rydaholm Book of Herbs, Tillandz's Flora Åboensis, Palmberg's Serta Florea Suecana, Bromelii Chloros Gothica and Rudbeckii Hortus Upsaliensis...."Linnaeus entered the Växjö Katedralskola in 1724, where he studied Greek, Hebrew and mathematics, a curriculum designed for boys preparing for the priesthood. In the last year at the gymnasium, Linnaeus's father visited to ask the professors how his son's studies were progressing. Rothman believed otherwise; the doctor offered to have Linnaeus live with his family in Växjö and to teach him physiology and botany. Nils accepted this offer. Rothman showed Linnaeus that botany was a serious sub
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