Spinner Shark Facts (Carcharhinus brevipinna)

Spinner Shark Facts (Carcharhinus brevipinna) The spinner shark (Carcharhinus brevipinna) is a type of requiem shark. It is a live-bearing, migratory shark found in warm ocean waters. Spinner sharks get their name from their interesting feeding strategy, which involves spinning through a school of fish, snapping them up, and often leaping into the air. Fast Facts: Spinner Shark Scientific Name: Carcharhinus brevipinnaDistinguishing Features: Slender shark with long snout, black-tipped fins, and habit of spinning through water when feeding.Average Size: 2 m (6.6 ft) length; 56 kg (123 lb) weightDiet: CarnivorousLife Span: 15 to 20 yearsHabitat: Coastal waters of the Atlantic, Pacific, and Indian OceansConservation Status: Near ThreatenedKingdom: AnimaliaPhylum: ChordataClass: ChondrichthyesOrder: CarcharhiniformesFamily: CarcharhinidaeFun Fact: Spinner sharks dont eat humans, but will bite if they are excited by other food. Description The spinner shark has a long and pointed snout, slender body, and relatively small first dorsal fin. Adults have black-tipped fins that look as though they were dipped in ink. The upper body is gray or bronze, while the lower body is white. On average, adults are 2 m (6.6 ft) long and weigh 56 kg (123 lb). The largest recorded specimen was 3 m (9.8 ft) long and weighed 90 kg (200 lb). Spinner shark. Spinner sharks and blacktip sharks are commonly confused with each other. The spinner has a slightly more triangular dorsal fin that is further back on the body. An adult spinner shark also has a distinctive black tip on its anal fin. However, juveniles lack this marking and the two species share similar behaviors, so its difficult to tell them apart. Distribution Due to difficulty distinguishing between blacktip and spinner sharks, the spinners distribution is uncertain. It can be found in the Atlantic, Indian, and Pacific Oceans, with the exception of the eastern Pacific. The species prefers warm coastal water that is less than 30 m (98 ft) deep, but some subpopulations migrate into deeper water. Spinner shark distribution. Chris_huh Diet and Predators Bony fishes are the staple of the spinner sharks diet. The sharks also eat octopus, squid, cuttlefish, and stingrays. The sharks teeth are made for grabbing prey rather than cutting it. A group of spinner sharks chases a school of fish then charges it from below. A spinning shark snaps up fish whole, often carrying enough momentum to leap into the air. Blacktip sharks also employ this hunting technique, although it is less common. Humans are the spinner sharks primary predator, but spinner sharks are also eaten by larger sharks. Reproduction and Life Cycle Spinner sharks and other requiem sharks are viviparous. Mating occurs from spring to summer. The female has two uteri, which are divided into compartments for each embryo. Initially, each embryo lives off its yolk sac. The yolk sac forms a placental connection with the female, which then provides nutrients until the pups are born. Gestation lasts from 11 to 15 months. Mature females give birth to 3 to 20 pups every other year. Spinner sharks start reproducing between the ages of 12 and 14 and can live until they are 15 to 20 years old. Spinner Sharks and Humans Spinner sharks dont eat large mammals, so bites from this species are uncommon and not fatal. The fish will bite if provoked or excited during a feeding frenzy. As of 2008, a total of 16 unprovoked bites and one provoked attack were attributed to spinner sharks. The shark is valued in sport fishing for the challenge it presents as it leaps from the water. Commercial fishermen sell the fresh or salted meat for food, the fins for shark fin soup, the skin for leather, and the liver for its vitamin-rich oil. Conservation Status The IUCN classifies the spinner shark as near threatened worldwide and vulnerable along the southeastern United States. The number of sharks and the population trend is unknown, mainly because spinner sharks are so often confused with other requiem sharks. Because spinner sharks live along highly populated coasts, they are subject to pollution, habitat encroachment, and habit degradation. However, overfishing poses the most significant threat. The US National Marine Fisheries Service 1999 Fishery Management Plan for Atlantic Tunas, Swordfish, and Sharks sets bag limits for recreational fishing and quotas for commercial fishing. While sharks of the species grow quickly, the age at which they breed approximates their maximum lifespan. Sources Burgess, G.H. 2009. Carcharhinus brevipinna. The IUCN Red List of Threatened Species 2009: e.T39368A10182758. doi:10.2305/IUCN.UK.2009-2.RLTS.T39368A10182758.enCapape, C.; Hemida, F.; Seck, A.A.; Diatta, Y.; Guelorget, O. Zaouali, J. (2003). Distribution and reproductive biology of the spinner shark, Carcharhinus brevipinna (Muller and Henle, 1841) (Chondrichthyes: Carcharhinidae). Israel Journal of Zoology. 49 (4): 269–286. doi:10.1560/DHHM-A68M-VKQH-CY9FCompagno, L.J.V. (1984). Sharks of the World: An Annotated and Illustrated Catalogue of Shark Species Known to Date. Rome: Food and Agricultural Organization. pp. 466–468. ISBN 92-5-101384-5.Dosay-Akbulut, M. (2008). The phylogenetic relationship within the genus Carcharhinus. Comptes Rendus Biologies. 331 (7): 500–509. doi:10.1016/j.crvi.2008.04.001Fowler, S.L.; Cavanagh, R.D.; Camhi, M.; Burgess, G.H.; Cailliet, G.M.; Fordham, S.V.; Simpfendorfer, C.A. Musick, J.A. (2005). Sharks, Rays and Chimaeras: The Sta tus of the Chondrichthyan Fishes. International Union for Conservation of Nature and Natural Resources. pp. 106–109, 287–288. ISBN 2-8317-0700-5.

Lead Essays - Chemical Elements, Native Element Minerals

Lead Essays - Chemical Elements, Native Element Minerals Lead subject = Chemistry title = Lead Lead is a lustrous, silvery metal that tarnishes in the presence of air and becomes a dull bluish gray. Soft and flexible, it has a low melting point (327 C). Its chemical symbol, Pb, is from plumbum, the Latin word for waterworks, because of lead's extensive use in ancient water pipes. Itsatomic number is 82; its atomic weight is 207.19. Lead and lead compounds can be highly toxic when eaten or inhaled. Although lead is absorbed very slowly into the body, its rate of excretion is even slower. Thus, with constant exposure, lead accumulates gradually in the body. It is absorbed by the red blood cells and circulated through the body where it becomes concentrated in the soft tissues, especially the liver and kidneys. Lead can cause damage in the central nervous system and apparently can damage the cells making up the blood-brain barrier that protects the brain from many harmful chemicals. Symptoms of lead poisoning include loss of appetite, weakness, anemia, vomiting, and convulsions, sometimes leading to permanent brain damage or death. Children who ingest chips of old, lead-containing paint or are exposed to dust from the deterioration of such paint may exhibit symptoms. Levels of environmental lead considered nontoxic may also be involved in increased hypertension in a significant number of persons, according to studies released in the mid-1980s. As a result, the U.S. Centers for Disease Control in recent years have been revising downward the levels of environmental lead that it would consider safe. At one time, lead poisoning was common among those who worked with lead, but such workplace hazards have been largely curtailed. Lead has been used by humans since ancient times. It was used in ancient Egypt in coins, weights, ornaments, utensils, ceramic glazes, and solder. Lead is mentioned in the Old Testament. The Romans conveyed drinking water in lead pipes, some of which are still in operation. Roman slaves extracted and prepared the lead, describes a disease among the slaves that was clearly lead poisoning. Because of their potential toxicity, lead water pipes are no longer being installed. The greatest single use of lead metal today is in the plates of storage batteries for automobiles. The protective oxidation layer formed by lead in contact with such substances as air, sulfuric acid, and fluorine makes it highly resistant to corrosion. For this reason, lead has been used to make drainage pipes and lead chambers in sulfuric acid factories. It is also used as a roofing material. The softness and malleability of lead make it useful for sheathing telephone and television cables. Lead is used in solder because of its low melting point. When combined with tin, lead forms solder alloys that are stronger than lead alone, with melting points lower than those of either original metal. Lead has the highest density of all metals in common use, which, for example, makes it useful as a counterweight in the keels of ships. Because of their high density, lead bullets and shot encounter little air resistance and thus achieve excellent striking power. Shot is produced by allowing molten lead to drip down from heights up to 38.10 m (125 ft). The drops become spherical and are condensed by the cooling action of the air before being collected in a tank filled with water or oil. Lead's density and softness also make it highly suitable for damping sound and vibrations. To isolate them from vibration, heavy machinery and even whole buildings are placed on lead blocks. Because the effectiveness of shielding against gamma and X rays depends largely on the density of the shield, lead is used in the protective shielding of X-ray machines and nuclear reactors. Tetraethyl lead or tetramethyl lead (PbEt4) has often been added to gasoline to improve engine efficiency and reduce gasoline consumption in automobiles. Because of the toxic effect of lead on the environment, however, plans call for phasing out this use. Lead azide is sensitive to striking and is highly explosive; it is frequently used as a detonator of explosives. Lead iodide is a light yellow substance that is used as a dye in such processes as coloring bronze. It has light-sensitive properties comparable to those of silver salts. More Uses the metal and the dioxide are used in storage batteries, cable covering, plumbing, ammunition manufacture of PbEt4 - an antiknock compound in petrol. environmental concern with lead poisoning, (and cheaper unleaded petrol prices) is slowly resulting in less use of lead in petrol the metal is very effective as a sound absorber, a radiation shield around X-ray equipment and nuclear reactors used extensively in paints, although recently the use of lead in paints has been drastically curtailed to eliminate or reduce health hazards the oxide is used in producing fine