Chondrichthyes is a class that contains the cartilaginous fishes: they are jawed vertebrates with paired fins, paired nares, scales, a heart with its chambers in series, skeletons made of cartilage rather than bone. The class is divided into two subclasses: Holocephali. Within the infraphylum Gnathostomata, cartilaginous fishes are distinct from all other jawed vertebrates; the skeleton is cartilaginous. The notochord is replaced by a vertebral column during development, except in Holocephali, where the notochord stays intact. In some deepwater sharks, the column is reduced; as they do not have bone marrow, red blood cells are produced in the epigonal organ. They are produced in the Leydig's organ, only found in certain cartilaginous fishes; the subclass Holocephali, a specialized group, lacks both the Leydig's and epigonal organs. Apart from electric rays, which have a thick and flabby body, with soft, loose skin, chondrichthyans have tough skin covered with dermal teeth called placoid scales, making it feel like sandpaper.
In most species, all dermal denticles are oriented in one direction, making the skin feel smooth if rubbed in one direction and rough if rubbed in the other. The pectoral and pelvic girdles, which do not contain any dermal elements, did not connect. In forms, each pair of fins became ventrally connected in the middle when scapulocoracoid and pubioischiadic bars evolved. In rays, the pectoral fins have connected to the head and are flexible. One of the primary characteristics present in most sharks is the heterocercal tail, which aids in locomotion. Chondrichthyans have toothlike scales called placoid scales. Denticles provide protection, in most cases, streamlining. Mucous glands exist in some species, as well, it is assumed that their oral teeth evolved from dermal denticles that migrated into the mouth, but it could be the other way around, as the teleost bony fish Denticeps clupeoides has most of its head covered by dermal teeth. This is most a secondary evolved characteristic, which means there is not a connection between the teeth and the original dermal scales.
The old placoderms had sharp bony plates in their mouth. Thus, it is unknown whether the oral teeth evolved first, it has been suggested that the original bony plates of all vertebrates are now gone and that the present scales are just modified teeth if both the teeth and body armor had a common origin a long time ago. However, there is no evidence of this. All chondrichthyans breathe through five depending on the species. In general, pelagic species must keep swimming to keep oxygenated water moving through their gills, whilst demersal species can pump water in through their spiracles and out through their gills. However, this is only a general rule and many species differ. A spiracle is a small hole found behind each eye; these can be tiny and circular, such as found on the nurse shark, to extended and slit-like, such as found on the wobbegongs. Many larger, pelagic species, such as the mackerel sharks and the thresher sharks, no longer possess them. Chondrichthyes nervous system is composed of a small brain, 8-10 pairs of cranial nerves, a spinal chord with spinal nerves.
They have several sensory organs. Ampullae of Lorenzini are a network of small jelly filled pores called electroreceptors which help the fish sense electric fields in water; this aids in finding prey and sensing temperature. The Lateral line system has modified epithelial cells located externally which sense motion and pressure in the water around them. Most subspecies have large well-developed eyes, they have powerful nostrils and olfactory organs. Their inner ears consist of 3 large semicircular canals which aid in orientation, their sound detecting apparatus has limited range and is more powerful at lower frequencies. Some subspecies have electric organs which can be used for predation, they have simple brains with the forebrain not enlarged. The structure and formation of myelin in their nervous systems are nearly identical to that of tetrapods, which has led evolutionary biologists to believe that Chondrichthyes were a cornerstone group in the evolutionary timeline of myelin development. Like all other jawed vertebrates, members of Chondrichthyes have an adaptive immune system.
Fertilization is internal. Development is live birth but can be through eggs; some rare species are viviparous. There is no parental care after birth. Capture-induced premature birth and abortion occurs in sharks/rays when fished. Capture-induced parturition is mistaken for natural birth by recreational fishers and is considered in commercial fisheries management despite being shown to occur in at least 12% of live bearing sharks and rays; the class Chondrichthyes has two subclasses: the subclass Elasmobranchii
Tableau encyclopédique et méthodique
The Tableau encyclopédique et méthodique des trois regnes de la nature was an illustrated encyclopedia of plants and minerals, notable for including the first scientific descriptions of many species, for its attractive engravings. It was published in Paris by Charles Joseph Panckoucke, from 1788 on. Although its several volumes can be considered a part of the greater Encyclopédie méthodique, they were titled and issued separately. Contributors: Jean-Baptiste Lamarck Pierre Joseph Bonnaterre Louis Jean Pierre Vieillot Jean Guillaume Bruguière Individual prints from this work today can sell for hundreds of dollars apiece. Cambridge University Library account Christabel P. Braunrot & Kathleen Hardesty Doig, 1995 The Encyclopédie méthodique: an introduction, Studies in Voltaire and the Eighteenth Century, 327: 1–152. Robert Darnton, 1979 The business of Enlightenment: a publishing history of the Encyclopédie Cambridge, Mass.: Bel,knap Press. George B. Watts,1965 "Thomas Jefferson, the'Encyclopedie' and the'Encyclopedie methodique French Review 38:318-25
The North Sea is a marginal sea of the Atlantic Ocean located between the United Kingdom, Norway, Germany, the Netherlands and France. An epeiric sea on the European continental shelf, it connects to the ocean through the English Channel in the south and the Norwegian Sea in the north, it is more than 970 kilometres long and 580 kilometres wide, with an area of 570,000 square kilometres. The North Sea has long been the site of important European shipping lanes as well as a major fishery; the sea is a popular destination for recreation and tourism in bordering countries and more has developed into a rich source of energy resources including fossil fuels and early efforts in wave power. The North Sea has featured prominently in geopolitical and military affairs in Northern Europe, it was important globally through the power northern Europeans projected worldwide during much of the Middle Ages and into the modern era. The North Sea was the centre of the Vikings' rise. Subsequently, the Hanseatic League, the Netherlands, the British each sought to dominate the North Sea and thus access to the world's markets and resources.
As Germany's only outlet to the ocean, the North Sea continued to be strategically important through both World Wars. The coast of the North Sea presents a diversity of geographical features. In the north, deep fjords and sheer cliffs mark the Norwegian and Scottish coastlines, whereas in the south, the coast consists of sandy beaches and wide mudflats. Due to the dense population, heavy industrialization, intense use of the sea and area surrounding it, there have been various environmental issues affecting the sea's ecosystems. Adverse environmental issues – including overfishing and agricultural runoff and dumping, among others – have led to a number of efforts to prevent degradation of the sea while still making use of its economic potential; the North Sea is bounded by the Orkney Islands and east coast of Great Britain to the west and the northern and central European mainland to the east and south, including Norway, Germany, the Netherlands and France. In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean.
In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively. In the north it is bordered by the Shetland Islands, connects with the Norwegian Sea, which lies in the north-eastern part of the Atlantic; the North Sea is more than 970 kilometres long and 580 kilometres wide, with an area of 570,000 square kilometres and a volume of 54,000 cubic kilometres. Around the edges of the North Sea are sizeable islands and archipelagos, including Shetland and the Frisian Islands; the North Sea receives freshwater from a number of European continental watersheds, as well as the British Isles. A large part of the European drainage basin empties into the North Sea, including water from the Baltic Sea; the largest and most important rivers flowing into the North Sea are the Elbe and the Rhine – Meuse watershed. Around 185 million people live in the catchment area of the rivers discharging into the North Sea encompassing some industrialized areas.
For the most part, the sea lies on the European continental shelf with a mean depth of 90 metres. The only exception is the Norwegian trench, which extends parallel to the Norwegian shoreline from Oslo to an area north of Bergen, it has a maximum depth of 725 metres. The Dogger Bank, a vast moraine, or accumulation of unconsolidated glacial debris, rises to a mere 15 to 30 m below the surface; this feature has produced the finest fishing location of the North Sea. The Long Forties and the Broad Fourteens are large areas with uniform depth in fathoms; these great banks and others make the North Sea hazardous to navigate, alleviated by the implementation of satellite navigation systems. The Devil's Hole lies 200 miles east of Scotland; the feature is a series of asymmetrical trenches between 20 and 30 kilometres long and two kilometres wide and up to 230 metres deep. Other areas which are less deep are Fisher Bank and Noordhinder Bank; the International Hydrographic Organization defines the limits of the North Sea as follows: On the Southwest.
A line joining the Walde Lighthouse and Leathercoat Point. On the Northwest. From Dunnet Head in Scotland to Tor Ness in the Island of Hoy, thence through this island to the Kame of Hoy on to Breck Ness on Mainland through this island to Costa Head and to Inga Ness in Westray through Westray, to Bow Head, across to Mull Head and on to Seal Skerry and thence to Horse Island. On the North. From the North point of the Mainland of the Shetland Islands, across to Graveland Ness in the Island of Yell, through Yell to Gloup Ness and across to Spoo Ness in Unst island, through Unst to Herma Ness, on to the SW point of the Rumblings and to Muckle Flugga all these being included in the North Sea area.
The Pacific Ocean is the largest and deepest of Earth's oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean in the south and is bounded by Asia and Australia in the west and the Americas in the east. At 165,250,000 square kilometers in area, this largest division of the World Ocean—and, in turn, the hydrosphere—covers about 46% of Earth's water surface and about one-third of its total surface area, making it larger than all of Earth's land area combined; the centers of both the Water Hemisphere and the Western Hemisphere are in the Pacific Ocean. The equator subdivides it into the North Pacific Ocean and South Pacific Ocean, with two exceptions: the Galápagos and Gilbert Islands, while straddling the equator, are deemed wholly within the South Pacific, its mean depth is 4,000 meters. The Mariana Trench in the western North Pacific is the deepest point in the world, reaching a depth of 10,911 meters; the western Pacific has many peripheral seas. Though the peoples of Asia and Oceania have traveled the Pacific Ocean since prehistoric times, the eastern Pacific was first sighted by Europeans in the early 16th century when Spanish explorer Vasco Núñez de Balboa crossed the Isthmus of Panama in 1513 and discovered the great "southern sea" which he named Mar del Sur.
The ocean's current name was coined by Portuguese explorer Ferdinand Magellan during the Spanish circumnavigation of the world in 1521, as he encountered favorable winds on reaching the ocean. He called it Mar Pacífico, which in both Portuguese and Spanish means "peaceful sea". Important human migrations occurred in the Pacific in prehistoric times. About 3000 BC, the Austronesian peoples on the island of Taiwan mastered the art of long-distance canoe travel and spread themselves and their languages south to the Philippines and maritime Southeast Asia. Long-distance trade developed all along the coast from Mozambique to Japan. Trade, therefore knowledge, extended to the Indonesian islands but not Australia. By at least 878 when there was a significant Islamic settlement in Canton much of this trade was controlled by Arabs or Muslims. In 219 BC Xu Fu sailed out into the Pacific searching for the elixir of immortality. From 1404 to 1433 Zheng He led expeditions into the Indian Ocean; the first contact of European navigators with the western edge of the Pacific Ocean was made by the Portuguese expeditions of António de Abreu and Francisco Serrão, via the Lesser Sunda Islands, to the Maluku Islands, in 1512, with Jorge Álvares's expedition to southern China in 1513, both ordered by Afonso de Albuquerque from Malacca.
The east side of the ocean was discovered by Spanish explorer Vasco Núñez de Balboa in 1513 after his expedition crossed the Isthmus of Panama and reached a new ocean. He named it Mar del Sur because the ocean was to the south of the coast of the isthmus where he first observed the Pacific. In 1519, Portuguese explorer Ferdinand Magellan sailed the Pacific East to West on a Spanish expedition to the Spice Islands that would result in the first world circumnavigation. Magellan called the ocean Pacífico because, after sailing through the stormy seas off Cape Horn, the expedition found calm waters; the ocean was called the Sea of Magellan in his honor until the eighteenth century. Although Magellan himself died in the Philippines in 1521, Spanish Basque navigator Juan Sebastián Elcano led the remains of the expedition back to Spain across the Indian Ocean and round the Cape of Good Hope, completing the first world circumnavigation in a single expedition in 1522. Sailing around and east of the Moluccas, between 1525 and 1527, Portuguese expeditions discovered the Caroline Islands, the Aru Islands, Papua New Guinea.
In 1542–43 the Portuguese reached Japan. In 1564, five Spanish ships carrying 379 explorers crossed the ocean from Mexico led by Miguel López de Legazpi, sailed to the Philippines and Mariana Islands. For the remainder of the 16th century, Spanish influence was paramount, with ships sailing from Mexico and Peru across the Pacific Ocean to the Philippines via Guam, establishing the Spanish East Indies; the Manila galleons operated for two and a half centuries, linking Manila and Acapulco, in one of the longest trade routes in history. Spanish expeditions discovered Tuvalu, the Marquesas, the Cook Islands, the Solomon Islands, the Admiralty Islands in the South Pacific. In the quest for Terra Australis, Spanish explorations in the 17th century, such as the expedition led by the Portuguese navigator Pedro Fernandes de Queirós, discovered the Pitcairn and Vanuatu archipelagos, sailed the Torres Strait between Australia and New Guinea, named after navigator Luís Vaz de Torres. Dutch explorers, sailing around southern Africa engaged in discovery and trade.
In the 16th and 17th centuries Spain considered the Pacific Ocean a mare clausum—a sea closed to other naval powers. As the only known entrance from the Atlantic, the Strait of Magellan was at times patrolled by fleets sent to prevent entrance of non-Spanish ships. On the western side of the Pacific Ocean the Dutch threatened the Spanish Philippines; the 18th cen
A chordate is an animal constituting the phylum Chordata. During some period of their life cycle, chordates possess a notochord, a dorsal nerve cord, pharyngeal slits, an endostyle, a post-anal tail: these five anatomical features define this phylum. Chordates are bilaterally symmetric; the Chordata and Ambulacraria together form the superphylum Deuterostomia. Chordates are divided into three subphyla: Vertebrata. There are extinct taxa such as the Vetulicolia. Hemichordata has been presented as a fourth chordate subphylum, but now is treated as a separate phylum: hemichordates and Echinodermata form the Ambulacraria, the sister phylum of the Chordates. Of the more than 65,000 living species of chordates, about half are bony fish that are members of the superclass Osteichthyes. Chordate fossils have been found from as early as the Cambrian explosion, 541 million years ago. Cladistically, vertebrates - chordates with the notochord replaced by a vertebral column during development - are considered to be a subgroup of the clade Craniata, which consists of chordates with a skull.
The Craniata and Tunicata compose the clade Olfactores. Chordates form a phylum of animals that are defined by having at some stage in their lives all of the following anatomical features: A notochord, a stiff rod of cartilage that extends along the inside of the body. Among the vertebrate sub-group of chordates the notochord develops into the spine, in wholly aquatic species this helps the animal to swim by flexing its tail. A dorsal neural tube. In fish and other vertebrates, this develops into the spinal cord, the main communications trunk of the nervous system. Pharyngeal slits; the pharynx is the part of the throat behind the mouth. In fish, the slits are modified to form gills, but in some other chordates they are part of a filter-feeding system that extracts particles of food from the water in which the animals live. Post-anal tail. A muscular tail that extends backwards behind the anus. An endostyle; this is a groove in the ventral wall of the pharynx. In filter-feeding species it produces mucus to gather food particles, which helps in transporting food to the esophagus.
It stores iodine, may be a precursor of the vertebrate thyroid gland. There are soft constraints that separate chordates from certain other biological lineages, but are not part of the formal definition: All chordates are deuterostomes; this means. All chordates are based on a bilateral body plan. All chordates are coelomates, have a fluid filled body cavity called a coelom with a complete lining called peritoneum derived from mesoderm; the following schema is from the third edition of Vertebrate Palaeontology. The invertebrate chordate classes are from Fishes of the World. While it is structured so as to reflect evolutionary relationships, it retains the traditional ranks used in Linnaean taxonomy. Phylum Chordata †Vetulicolia? Subphylum Cephalochordata – Class Leptocardii Clade Olfactores Subphylum Tunicata – Class Ascidiacea Class Thaliacea Class Appendicularia Class Sorberacea Subphylum Vertebrata Infraphylum incertae sedis Cyclostomata Superclass'Agnatha' paraphyletic Class Myxini Class Petromyzontida or Hyperoartia Class †Conodonta Class †Myllokunmingiida Class †Pteraspidomorphi Class †Thelodonti Class †Anaspida Class †Cephalaspidomorphi Infraphylum Gnathostomata Class †Placodermi Class Chondrichthyes Class †Acanthodii Superclass Osteichthyes Class Actinopterygii Class Sarcopterygii Superclass Tetrapoda Class Amphibia Class Sauropsida Class Synapsida Craniates, one of the three subdivisions of chordates, all have distinct skulls.
They include the hagfish. Michael J. Benton commented that "craniates are characterized by their heads, just as chordates, or all deuterostomes, are by their tails". Most craniates are vertebrates; these consist of a series of bony or cartilaginous cylindrical vertebrae with neural arches that protect the spinal cord, with projections that link the vertebrae. However hagfish have incomplete braincases and no vertebrae, are therefore not regarded as vertebrates, but as members of the craniates, the group from which vertebrates are thought to have evolved; however the cladistic exclusion of hagfish from the vertebrates is controversial, as they ma
In biology, a type is a particular specimen of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralize the defining features of that particular taxon. In older usage, a type was a taxon rather than a specimen. A taxon is a scientifically named grouping of organisms with other like organisms, a set that includes some organisms and excludes others, based on a detailed published description and on the provision of type material, available to scientists for examination in a major museum research collection, or similar institution. According to a precise set of rules laid down in the International Code of Zoological Nomenclature and the International Code of Nomenclature for algae and plants, the scientific name of every taxon is always based on one particular specimen, or in some cases specimens. Types are of great significance to biologists to taxonomists. Types are physical specimens that are kept in a museum or herbarium research collection, but failing that, an image of an individual of that taxon has sometimes been designated as a type.
Describing species and appointing type specimens is part of scientific nomenclature and alpha taxonomy. When identifying material, a scientist attempts to apply a taxon name to a specimen or group of specimens based on his or her understanding of the relevant taxa, based on having read the type description, preferably based on an examination of all the type material of all of the relevant taxa. If there is more than one named type that all appear to be the same taxon the oldest name takes precedence, is considered to be the correct name of the material in hand. If on the other hand the taxon appears never to have been named at all the scientist or another qualified expert picks a type specimen and publishes a new name and an official description; this process is crucial to the science of biological taxonomy. People's ideas of how living things should be grouped shift over time. How do we know that what we call "Canis lupus" is the same thing, or the same thing, as what they will be calling "Canis lupus" in 200 years' time?
It is possible to check this because there is a particular wolf specimen preserved in Sweden and everyone who uses that name – no matter what else they may mean by it – will include that particular specimen. Depending on the nomenclature code applied to the organism in question, a type can be a specimen, a culture, an illustration, or a description; some codes consider a subordinate taxon to be the type, but under the botanical code the type is always a specimen or illustration. For example, in the research collection of the Natural History Museum in London, there is a bird specimen numbered 1822.214.171.124. This is a specimen of a kind of bird known as the spotted harrier, which bears the scientific name Circus assimilis; this particular specimen is the holotype for that species. That species was named and described by Jardine and Selby in 1828, the holotype was placed in the museum collection so that other scientists might refer to it as necessary. Note that at least for type specimens there is no requirement for a "typical" individual to be used.
Genera and families those established by early taxonomists, tend to be named after species that are more "typical" for them, but here too this is not always the case and due to changes in systematics cannot be. Hence, the term name-bearing type or onomatophore is sometimes used, to denote the fact that biological types do not define "typical" individuals or taxa, but rather fix a scientific name to a specific operational taxonomic unit. Type specimens are theoretically allowed to be aberrant or deformed individuals or color variations, though this is chosen to be the case, as it makes it hard to determine to which population the individual belonged; the usage of the term type is somewhat complicated by different uses in botany and zoology. In the PhyloCode, type-based definitions are replaced by phylogenetic definitions. In some older taxonomic works the word "type" has sometimes been used differently; the meaning was similar in the first Laws of Botanical Nomenclature, but has a meaning closer to the term taxon in some other works: Ce seul caractère permet de distinguer ce type de toutes les autres espèces de la section.
… Après avoir étudié ces diverses formes, j'en arrivai à les considérer comme appartenant à un seul et même type spécifique. Translation: This single character permits distinguish this type from all other species of the section... After studying the diverse forms, I came to consider them as belonging to the one and the same specific type. In botanical nomenclature, a type, "is that element to which the name of a taxon is permanently attached." In botany a type is either an illustration. A specimen is a real plant and kept safe, "curated", in a herbarium. Examples of where an illustration may serve as a type include: A detailed drawing, etc. depicting the plant, from the early days of plant taxonomy. A dried plant was difficult to transport and hard to keep safe for the future. Skilled botanical artists were sometimes employed by a botanist to make a faithful and detailed illustration; some such illustrations have become the best record a
Osteichthyes, popularly referred to as the bony fish, is a diverse taxonomic group of fish that have skeletons composed of bone tissue, as opposed to cartilage. The vast majority of fish are members of Osteichthyes, an diverse and abundant group consisting of 45 orders, over 435 families and 28,000 species, it is the largest class of vertebrates in existence today. The group Osteichthyes is divided into lobe-finned fish; the oldest known fossils of bony fish are about 420 million years old, which are transitional fossils, showing a tooth pattern, in between the tooth rows of sharks and bony fishes. Osteichthyes can be compared to Euteleostomi. In paleontology, the terms are synonymous. In ichthyology, the difference is that Euteleostomi presents a cladistic view which includes the terrestrial tetrapods that evolved from lobe-finned fish, whereas prior to 2014 the view of most ichthyologists was that Osteichthyes includes only fishes, were therefore paraphyletic. However, in 2014, an ichthyology paper was published with phylogenetic trees that treat the Osteichthyes as a clade including tetrapods.
Bony fish are characterized by a stable pattern of cranial bones, medial insertion of mandibular muscle in the lower jaw. The head and pectoral girdles are covered with large dermal bones; the eyeball is supported by a sclerotic ring of four small bones, but this characteristic has been lost or modified in many modern species. The labyrinth in the inner ear contains large otoliths; the braincase, or neurocranium, is divided into anterior and posterior sections divided by a fissure. Early bony fish had simple lungs. In many bony fish these have evolved into swim bladders, which help the body create a neutral balance between sinking and floating, they do not have fin spines, but instead support the fin with lepidotrichia. They have an operculum, which helps them breathe without having to swim. Bony fish have no placoid scales. Mucus glands coat the body. Most have overlapping ganoid, cycloid or ctenoid scales. Traditionally, Osteichthyes is considered a class, recognised on having a swim bladder, only three pairs of gill arches, hidden behind a bony operculum and a predominately bony skeleton.
Under this classification systems, the Osteichthyes are paraphyletic with regard to land vertebrates as the common ancestor of all Osteichthyes includes tetrapods amongst its descendants. The largest subclass, the Actinopterygii are monophyletic, but with the inclusion of the smaller sub-class Sarcopterygii, Osteichthyes is paraphyletic; this has led to an alternative cladistic classification, splitting the Osteichthyes into two full classes. Osteichthyes is under this scheme monophyletic, as it includes the tetrapods, making it a synonym of the clade Euteleostomi. Most bony fish belong to the ray-finned fish; the phylogeny of living Osteichthyes, including the tetrapods, is shown in the cladogram. Whole-genome duplication took place in the ancestral Osteichthyes. All bony fish possess gills. For the majority this is their main means of respiration. Lungfish and other osteichthyan species are capable of respiration through lungs or vascularized swim bladders. Other species can respire through their skin, and/or stomach.
Osteichthyes are primitively ectothermic, meaning that their body temperature is dependent on that of the water. But some of the larger marine osteichthyids, such as the opah and tuna have independently evolved various levels of endothermy. Bony fish can be any type of heterotroph: numerous species of omnivore, herbivore, filter-feeder or detritivore are documented; some bony fish are hermaphrodites, a number of species exhibit parthenogenesis. Fertilization is external, but can be internal. Development is oviparous but can be ovoviviparous, or viviparous. Although there is no parental care after birth, before birth parents may scatter, guard or brood eggs, with sea horses being notable in that the males undergo a form of "pregnancy", brooding eggs deposited in a ventral pouch by a female; the ocean sunfish is the heaviest bony fish in the world, while the longest is the king of herrings, a type of oarfish. Specimens of ocean sunfish have been observed up to 3.3 metres in length and weighing up to 2,303 kilograms.
Other large bony fish include the Atlantic blue marlin, some specimens of which have been recorded as in excess of 820 kilograms, the black marlin, some sturgeon species, the giant and goliath grouper, which both can exceed 300 kilograms in weight. In contrast, the dwarf pygmy goby measures a minute 15 millimetres. Arapaima gigas is the largest species of freshwater bony fish; the largest bony fish was Leedsichthys, which dwarfed the beluga sturgeon, ocean sunfish, giant grouper, all the other giant bony fishes alive today. Cartilaginous fishes can be further divided into sharks and chimaeras. In the table below, the comparison is made between sharks and bony fishes. For the further differences with rays, see sharks versus rays. Ostracoderm - armoured jawless fish. Prehistoric fish Helfman, G. S.. E; the Diversity of Fishes. Blackwell Sciences. ISBN 978-0-86542-256-8