Some Anthozoans (corals etc.) around the tropical island of Koh Tao/Thailand

Author: papscurtis
Keywords: scuba diving tauchen corals korallen anthozoa anemone flower animals blumentiere koh tao thailand
Added: October 23, 2008

. . . PICTURES OF THESE CORALS AT: http://www.shareapic.net/content.php?gid=426285 . . . . Corals were photgraphed during 3 week tour around Sulawesi. Corals are marine organisms from the class Anthozoa and exist as small sea anemonelike polyps, typically in colonies of many identical individuals. The group includes the important reef builders that are found in tropical oceans, which secrete calcium carbonate to form a hard skeleton. A coral "head", commonly perceived to be a single organism, is formed from thousands of individual but genetically identical polyps, each polyp only a few millimeters in diameter. Over thousands of generations, the polyps lay down a skeleton that is characteristic of their species. A head of coral grows by asexual reproduction of the individual polyps. Corals also breed sexually by spawning, with corals of the same species releasing gametes simultaneously over a period of one to several nights around a full moon. Although corals can catch plankton using stinging cells on their tentacles, these animals obtain most of their nutrients from symbiotic unicellular algae called zooxanthellae. While a coral head appears to be a single organism, it is actually a head of many individual, yet genetically identical, polyps. The polyps are multicellular organisms that feed on a variety of small organisms, from microscopic plankton to small fish. Polyps are usually a few millimeters in diameter, and are formed by a layer of outer epithelium and inner jellylike tissue known as the mesoglea. They are radially symmetrical with tentacles surrounding a central mouth, the only opening to the stomach or coelenteron, through which both food is ingested and waste expelled. The stomach closes at the base of the polyp, where the epithelium produces an exoskeleton called the basal plate or calicle. This is formed by a thickened calciferous ring with six supporting radial ridges. These structures grow vertically and project into the base of the polyp. When polyps are physically stressed, they contract into the calyx so that virtually no part is exposed above the skeletal platform. This protects the organism from predators and the elements. The polyp grows by extension of vertical calices which are occasionally septated to form a new, higher, basal plate. Over many generations this extension forms the large calciferous (Calcium containing) structures of corals and ultimately coral reefs. Formation of the calciferous exoskeleton involves deposition of the mineral aragonite by the polyps from calcium ions they acquire from seawater. The rate of deposition, while varying greatly between species and environmental conditions, can be as much as 10 g / m² of polyp / day (0.3 ounce / sq yd / day). This is light dependent, with night-time production 90% lower than that during the middle of the day. Corals predominantly reproduce sexually, with 25% of hermatypic corals (stony corals) forming single sex (gonochoristic) colonies, whilst the rest are hermaphroditic. About 75% of all hermatypic corals "broadcast spawn" by releasing gametes - eggs and sperm - into the water to spread colonies over large distances. The gametes fuse during fertilisation to form a microscopic larvum called a planula, typically pink and elliptical in shape; a moderately sized coral colony can form several thousands of these larvae per year to overcome the huge odds against formation of a new colony. The hermatypic, stony corals are often found in coral reefs, large calcium carbonate structures generally found in shallow, tropical water. Reefs are built up from coral skeletons and held together by layers of calcium carbonate produced by coralline algae. Reefs are extremely diverse marine ecosystems being host to over 4,000 species of fish, massive numbers of cnidarians, molluscs, crustaceans, and many other animals. Although corals first appeared in the Cambrian period, some 542 million years ago, fossils are extremely rare until the Ordovician period, 100 million years later, when Rugose and Tabulate corals became widespread. Corals are highly sensitive to environmental changes. Scientists have predicted that over 50% of the coral reefs in the world may be destroyed by the year 2030. Coral reefs also provide recreational scuba diving and snorkeling tourism.

Author: albinbaraga
Keywords: Corals Coral Korale Korala Indonesia Indonezija Sulawesi Celebes Sulavezi Togean Islands Island oto�je otok nature
Added: September 13, 2008

Características generales de Cnidarios en general y los corales en particular.

Author: 35ciencias
Keywords: antozoos anthozoa isfdyt35
Added: August 31, 2008

a mutated animone from the depths of a nuclear waste dump site( the name is derived from anthozoa the class that animones and coral polyps belong to)

Author: stormkwick
Keywords: spore dance off
Added: June 18, 2008

Trabalho de Biologia Anna D.,Bruna D.,Jéssica D. e Tieli D. Participação MEGA especial: JOSA Armandinho-Casinha Antozoários ou Anthozoa São invertebrados possuem tentáculosÉ tudo que Anthozoas têmEntre a epiderme e a gastrodermeExiste a mesogléia (2x) Dos Anthozoas não seiA biologia nos ensinaráViver lá dentro do marSei que Deus ajudará (2x) Animais diblásticos possuem tentáculosÉ tudo que Anthozoas têmSe locomovem nas medusas vivem em colôniasÀs vezes solitários (2x) E pra se reproduzirO comum é liberarÓvulos e espermas na águaReprodução assexuada (2x) A felicidade se encontraNas coisas mais simples da terraSistema digestivo incompletoTambém pode ser intracelular Na natureza tô perto de DeusCurtindo os Anthozoas respirarPor trocas gasosas se dãoEntre as células e a água São invertebrados possuem tentáculosÉ tudo que Anthozoas têmEntra a epiderme e a gastrodermeExiste a mesogléia (2x) PS.:Qualidade do vídeo tri³ booa. =O

Author: lolo5692
Keywords: Antozoários Anthozoa
Added: May 9, 2008