examples of cartilaginous fish
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Fishare very diverse and are categorized in many ways. This article is an overview of some of the more common types of fish. Although most fishspecies have probably been discovered and described, about 250 new ones are still discovered every year. According to FishBase, 31,500 species of fish had been described by January 2010. That is more than the combined total of all other vertebrates: mammals, amphibians, reptiles and birds.
Fish systematics is the formal description and organisation of fish taxa into systems. It is complex and still evolving. Controversies over "arcane, but important, details of classification are still quietly raging."
The term "fish" describes any non-tetrapodchordate, (i.e., an animal with a backbone), that has gills throughout life and has limbs, if any, in the shape of fins. Unlike groupings such as birds or mammals, fish are not a single clade but a paraphyletic collection of taxa, including jawless, cartilaginous and skeletal types.
Jawless fish are the most primitive fish. There is current debate over whether these are really fish at all. They have no jaw, no scales, no paired fins, and no bony skeleton. Their skin is smooth and soft to the touch, and they are very flexible. Instead of a jaw, they possess an oral sucker. They use this to fasten on to other fish, and then use their rasp-like teeth to grind through their host's skin into the viscera. Jawless fish inhabit both fresh and salt water environments. Some are anadromous, moving between both fresh and salt water habitats.
Extant jawless fish are either lamprey or hagfish. Juvenile lamprey feed by sucking up mud containing micro-organisms and organic debris. The lamprey has well developed eyes, while the hagfish has only primitive eyespots. The hagfish coats itself and carcasses it finds with noxious slime to deter predators, and periodically ties itself into a knot to scrape the slime off. It is the only invertebrate fish and the only animal which has a skull but no vertebral column. It has four hearts, two brains, and a paddle-like tail.
Cartilaginous fish have a cartilaginous skeleton. However, their ancestors were bony animals, and were the first fish to develop paired fins. Cartilaginous fish don't have swim bladders. Their skin is covered in denticles, that are as rough as sandpaper. Because cartilaginous fish do not have bone marrow, the spleen and special tissue around the gonads produces red blood cells. Some cartilaginous fishes possess an organ called Leydig's Organ which also produces red blood cells.
Bony fish include the lobe finned fish and the ray finned fish. The lobe finned fish is the class of fleshy finned fishes, consisting of lungfish, and coelacanths. They are bony fish with fleshy, lobed paired fins, which are joined to the body by a single bone. These fins evolved into the legs of the first tetrapod land vertebrates, amphibians. Ray finned fishes are so-called because they possess lepidotrichia or "fin rays", their fins being webs of skin supported by bony or horny spines ("rays").
There are three types of ray finned fishes: the chondrosteans, holosteans, and teleosts. The chondrosteans and holosteans are primitive fishes sharing a mixture of characteristics of teleosts and sharks. In comparison with the other chondrosteans, the holosteans are closer to the teleosts and further from sharks.
Teleosts are the most advanced or "modern" fishes. They are overwhelmingly the dominant class of fishes (or for that matter, vertebrates) with nearly 30,000 species, covering about 96 percent of all extant fish species. They are ubiquitous throughout fresh water and marine environments from the deep sea to the highest mountain streams. Included are ne
According to the FAO, there are currently (2004) four million commercial fishing vessels. About 1.3 million of these are decked vessels with enclosed areas. Nearly all of these decked vessels are mechanised, and 40,000 of them are over 100 tons. At the other extreme, two-thirds (1.8 million) of the undecked boats are traditional craft of various types, powered only by sail and oars. These boats are used by artisan fishers.
It is difficult to estimate the number of recreational fishing boats. They range in size from small dingies to large charter cruisers, and unlike commercial fishing vessels, are often not dedicated just to fishing.
Prior to the 1950s there was little standardisation of fishing boats. Designs could vary between ports and boatyards. Traditionally boats were built out of wood, but wood is not often used now because of cost and the difficulty in obtaining suitable timber. Fibreglass is used increasingly in smaller fishing vessels up to 25 metres (100 tons), while steel is usually used on vessels above 25 metres.
Early fishing vessels included rafts, dugout canoes, and boats constructed from a frame covered with hide or tree bark, along the lines of a coracle. The oldest boats found by archaeological excavation are dugout canoes dating back to the Neolithic Period around 7,000-9,000 years ago. These canoes were often cut from coniferous tree logs, using simple stone tools. A 7000 year-old sea going boat made from reeds and tar has been found in Kuwait. These early vessels had limited capability; they could float and move on water, but were not suitable for use any great distance from the shoreline. They were used mainly for fishing and hunting.
The development of fishing boats took place in parallel with the development of boats built for trade and war. Early navigators began to use animal skins or woven fabrics for sails. Affixed to a pole set upright in the boat, these sails gave early boats more range, allowing voyages of exploration.
Around 4000 B.C., Egyptians were building long narrow boats powered by many oarsmen. Over the next 1,000 years, they made a series of remarkable advances in boat design. They developed cotton-made sails to help their boats go faster with less work. Then they built boats large enough to cross the oceans. These boats had sails and oarsmen, and were used for travel and trade. By 3000 BC, the Egyptians knew how to assemble planks of wood into a ship hull. They used woven straps to lash planks together, and reeds or grass stuffed between the planks to seal the seams. An example of their skill is the Khufu ship, a vessel 143|ft|m in length entombed at the foot of the Great Pyramid of Giza around 2,500 BC and found intact in 1954.
At about the same time, the Scandinavians were also building innovative boats. People living near Kongens Lyngby in Denmark, came up with the idea of segregated hull compartments, which allowed the size of boats to gradually be increased. A crew of some two dozen paddled the wooden Hjortspring boat across the Baltic Sea long before the rise of the Roman Empire. Scandinavians continued to develop better ships, incorporating iron and other metal into the design and developing oars for propulsion.
The oldest Nordic shipfind is the Nydam boat, found preserved in the Nydam Mose bog in Sundeved, Denmark. It has been dendro dated to 310-320 AD., and is the oldest known boat to use clinker planking, where the planks overlap one another. Built of oak, it is 23 metres long and about 4 metres wide. It originally weighed over three tonnes and was rowed by thirty men.
By 1000 A.D. the Norsemen were pre-eminent on the oceans. They were skilled seamen and boat builders, with clinker-built boat designs that varied according to the type of boat. Trading boats, such as the knarrs, were wide to allow large cargo storage. Raiding boats, such as the longship, were long and narrow and very fast. The vessels they used for fishing were scaled down versions of their cargo boats. The Scandinavian innovations influenced fishing boat design long after the Viking period came to an end. For example, yoles from the Orkney island of Stroma were built in the same way as the Norse boats.
In the 15th century, the Dutch
Osteichthyes (ËŒÉ’stiË�ËˆÉªkÎ¸i.iË�z), also called bony fish, are a taxonomic group of fish that have bony, as opposed to cartilaginous, skeletons. The vast majority of fish are osteichthyes, which is an extremely diverse and abundant group consisting of over 29,000 species. It is the largest class of vertebrates in existence today. Osteichthyes is divided into the ray-finned fish (Actinopterygii) and lobe-finned fish (Sarcopterygii).
In most classification systems the Osteichthyes are paraphyletic with land vertebrates. That means that the nearest common ancestor of all Osteichthyes includes tetrapods amongst its descendants. Actinopterygii (ray-finned fish) are monophyletic, but the inclusion of Sarcopterygii in Osteichthyes causes Osteichthyes to be paraphyletic. Paradoxically, Sarcopterygii is considered monophyletic, as it includes tetrapods.
Traditionally, the bony fish had been treated as a class within the vertebrates, with Actinopterygii and Sarcopterygii as subclasses. However, some recent works have elevated Osteichthyes to superclass, with Actinopterygii and Sarcopterygii as classes.
All bony fish possess gills. For the majority this is their sole or 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, intestines, and/or stomach.
Osteichthyes are primatively ectothermic (cold blooded), meaning that their body temperature is dependent on that of the water. But some members of the family scombridae such as the swordfish and tuna have achieved various levels of endothermy. They can be any type of heterotroph: omnivore, carnivore, herbivore, or detritivore.
Some bony fish are hermaphrodites, and a number of species exhibit parthenogenesis. Fertilization is usually external, but can be internal. Development is usually oviparous (egg-laying) but can be ovoviviparous, or viviparous. Although there is usually no parental care after birth, before birth parents may scatter, hide, 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 largest 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|m|ft in length and weighing up to 2303|kg|lb. Other very large bony fish include the Atlantic blue marlin, some specimens of which have been recorded as in excess of 820|kg|lb, the black marlin, some sturgeon species, the giant grouper and the goliath grouper, both which can exceed 400|kg|lb in weight. In contrast, the dwarf pygmy goby measures a minute 15|mm|in.
Aquarium fish feed is plant or animal material intended for consumption by pet fish kept in aquariums or ponds. Fish foods normally contain macro nutrients, trace elements and vitamins necessary to keep captive fish in good health. Approximately 80% of fishkeeping hobbyists feed their fish exclusively prepared foods that most commonly are produced in flake, pellet or tablet form. Pelleted forms, some of which sink rapidly, are often used for larger fish or bottom feeding species such as loaches or catfish. Some fish foods also contain additives such as sex hormones or beta carotene to artificially enhance the color of ornamental fish. Prepared foods Prepared foods are those foods that are non-living and are made by the aquarist or bought already prepared for consumption for fish. Dry foods Flake food is a type of proprietary or artificially manufactured fish food consumed by a wide variety of tropical and saltwater fish and invertebrates. It is ideally suited to top dwellers and mid-water fish though numerous bottom dwelling species consume flake food once it has settled on the bottom. Flake food is baked to remove moisture, ensuring a longer shelf life. Generally the more moisture a particular example of fish food contains, the more readily it will deteriorate in quality. Dry foods is also available as pellets, sticks, tablets, granules, and wafers, manufactured to float or sink, depending on the species they are designed to feed. Vacation food Vacation foods — also known as "food blocks" — are designed to be placed inside the aquarium to forgo feeding while the owner is absent. These blocks release small amounts of food as they dissolve. Food blocks can be a good choice for smaller tropical fish, but can pollute the water. Medicated fishfood Medicated fishfood is a safe and effective method to deliver medication to fish. One advantage is that medicated food does not contaminate the aquatic environment and also, unlike bath treatments, does not negatively affect fish, filtration and algae growth in the aquarium. The parasites will get treated spot on by medicated food, because the fish is ingesting it. Freeze-dried and frozen fish diets Freeze-dried and frozen fish foods were primarily developed for tropical and marine fish and are useful in providing variety to the diet or specialist feeding needs of some species. These include tubifex worms, mosquito larvae, bloodworms, water fleas (Daphnia and Cyclops spp.) along with brine shrimp (Artemia salina). Frozen fish food Perishable food can be preserved by frozen storage, and is often sold in blister packs or resealable packets. These can contain a variety of ingredients such as bloodworms, Daphnia, or brine shrimp, and are commonly used to feed such fish as Discus which require a high protein diet. Live foods Live fish food include earthworms, sludge worms, water fleas, bloodworms, and feeder fish. Food for larvae and young fish include infusoria (Protozoa and other microorganisms), newly hatched brine shrimp and microworms. These are the most preferred type of food for fishes,but are difficult to get. However, freeze dried forms of earthworms, tubifex etc. are available now. Ingredients of quality fish food Fish food should ideally provide the fish with fat (for energy) and amino acids (building blocks of proteins) and the fish food (whether flake or pellet) must be speedily digested in order to prevent build up of intestinal gas, renal failure and infections (such as swim bladder problems and dropsy) and to avoid aquarium pollution due to excessive ammonia. Aquatic diets for carnivores must contain vegetable matter such as spirulina. Building block ingredients of fish food Amino acids are the basic components of proteins. An example of an aquatic diet that is a good source of amino acid is a crumbled hard boiled egg offered to small fry. Large amounts of DL-Methionine enhance the headgrowth of the Lionhead goldfish. Fats that are broken down into fatty acids are the main source of energy in fish especially for the heart and skeletal muscles. Fats also assists in vitamin absorption. Vitamins A, D, E and K are fat-soluble or can only be digested, absorbed, and transported in conjunction with fats. Carbohydrates are molecular substances that include sugars, starches, gums and celluloses. Most of the carbohydrates that are incorporated into aquatic diets are of plant origin and are sources of the enzyme amylase. Carbohydrates, however, are not a superior energy source for fish over protein or fat but digestible carbohydrates do spare protein for tissue building. Unlike in mammals, glycogen is not a significant storage depot of energy in fish. Sources of fish food Fish meal (protein source) have two basic types: (a) those produced from fishery wastes associated with the processing of fish for human consumption (such as salmon and tuna) and (b) those from specific fish (herring, menhaden and pollack) which are harvested solely for the purpose of producing fish meal. Shrimp meal is made from cull shrimp that are being processed before freezing or from whole shrimp that is not of suitable quality for human consumption. The material to be made into shrimp meal is dried (sun-dried or by using a dryer) and then ground. Shrimp meal is a source of pigments that enhances the desirable color in the tissues of fish. It is also a secondary supplemental protein source for fish. Squid meal is made from squid viscera portions from cannery plants including the eggs and testis. Squid Meal is a highly digestible protein source for fish which provides a full range of amino acids, vitamins, minerals and cholesterol (1.0â€“1.5%) of cholesterol suitable for fish fry and young fish. Brine shrimp (adult Artemia) is a common food source for fish that are available in adult-form, as eggs or freeze-dried. Brine shrimp is a source of protein, carotene (a color enhancer) and acts as a natural laxative in fish digestive systems. Brine shrimps can also supply the fish with vegetable matter due to their consumption of algae. Soybean meal is a high protein source for fish and has become a substitute for traditionally-used marine animal meals. Spirulina is a blue-green plant plankton rich in raw protein, vitamins A, B1, B2, B6, B12, C and E, beta-carotene, color enhancing pigments, a whole range of minerals, essential fatty acids and eight amino acids required for complete nutrition. Whole wheat (carbohydrates) is not the best source of energy in fish but is an excellent source of roughage for fish such as Goldfish and Koi. It is also a natural source of vitamin E which promotes growth and enhances coloration. Manufacturers Hagen Hikari Tetra Wardley
The cartilaginous fish, or Chondricthyes, include the sharks, rays, skates, and chimaeras. There are over eight hundred living species of sharks and rays, and about thirty species of chimaeras. Cartilaginous fish are true fish. They have fins and breathe with gills. Unlike the more familiar bony fish, the Osteichythes, the skeletons of the cartilaginous fish are made of cartilage. Other features that distinguish the cartilaginous fish from the bony fish are multiple gill slits, tiny toothlike scales, nostrils on the side of the head, teeth that are not fused to the jaw, and internal fertilization . Internal fertilization also occurs in some bony fish such as sea horses, guppies, and mollies. The ancestors of cartilaginous fish and bony fish diverged in the late Silurian, more than 400 million years ago. Sharks are large, long-lived, slow-growing ocean predators. The whale shark (Rhincodon typhus ) is the world's largest fish; adults can be as long as 18 meters (59 feet). The spiny dogfish shark (Squalus acanthias ) is the most studied shark, and while it rarely grows longer than 1.2 meters (almost 4 feet), it matures at 35 years and lives to be 70 or 80 years old. Sharks have internal fertilization and many shark species bear live young after a gestation of six or more months. The number of sharks in a clutch is often low, but can range from one or two to hundreds, depending on the species. The combination of slow maturity, long gestation, and small clutches means that shark populations cannot increase very rapidly. As a result, shark populations are very vulnerable to overfishing. Sharks are tremendous predators, with their mouths full of ever-sharp teeth and jaw strength capable of exerting over 2,500 kg/cm2 (30,000 psi) of pressure at the tooth tips. (A single shark may produce over ten thousand teeth in its lifetime, and as a result, the most common fossils of the cartilaginous fish are their teeth.) Sharks also have excellent senses of smell, waterborne vibrations, and the ability to sense the faint magnetic fields generated by the muscles of their prey. The large white shark (Carcharodon carcharias ) preys on seals, sea lions, and large fish, and has been known to attack swimmers and boats. Rays are bottom-dwelling fishes that are able to "fly" through the water with their enlarged and flattened pectoral fins. Stingrays can cause excruciating pain using a venomous stinger at the base of their tail. Electric rays can generate a shock of 200 volts. The manta ray has a wing span of up to 7 meters (almost 23 feet) and is sometimes seen following ships in the open ocean. Chimearas, also known as ratfishes, are a small group of rarely seen bottom-dwelling cartilaginous fish with large platelike teeth, no scales, and long skinny tails. see also Bony Fish; Ocean Ecosystems Virginia Card Carl, E. Biology of Fishes, 2nd ed. Philadelphia, PA: W. B. Saunders, Co., 1997. Moyers, Peter B., and Joseph J. Cech, Jr. Fishes: An Introduction to Ichthyology, 4th ed.Englewood Cliffs, NJ: Prentice Hall, 1999.
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Answers:Digestive system don't have stomach.
Answers:Bony skeleton They have their Endoskeleton entirely cartilaginous.
Answers:Bony fish have a (relatively) large gas bladder located ventral to their spine. Sharks and rays have a large liver that has neutrally buoyant oils when in motion. However, the weight of their bodies and this neutrally buoyant oil will cause them to slowly sink, which is compensated for by their heterocercal tails (the lower lobe is almost always smaller than the upper lobe, the exceptions being the long and short fin makos, which are designed to move very quickly over long distances, and so need a more efficient propulsion system).
Answers:Ablabys taenianotus Abudefduf vaigiensis mud sunfish