Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically live in compact colonies of many identical individual polyps. Corals species include the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.
Aristotle's pupil Theophrastus described the red coral, korallion, in his book on stones, implying it was a mineral, but he described it as a deep-sea plant in his Enquiries on Plants, where he also mentions large stony plants that reveal bright flowers when under water in the Gulf of Heroes.[2] Pliny the Elder stated boldly that several sea creatures including sea nettles and sponges "are neither animals nor plants, but are possessed of a third nature (tertius natura)".
Ejection increases the polyp's chance of surviving short-term stress—they can regain algae, possibly of a different species at a later time. If the stressful conditions persist, the polyp eventually dies.[26] Zooxanthellae are located within the corals' cytoplasm and due to the algae's photosynthetic activity, the internal pH of the coral can be raised; this behavior indicates that the zooxanthellae are responsible to some extent for the metabolism of their host corals [27] Reproduction[edit]
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These activities can damage coral but international projects such as Green Fins that encourage dive and snorkel centres to veja mais follow a Code of Conduct have been proven to mitigate these risks.[63] Jewelry[edit]
Presently, corals are classified as certain species of animals within the sub-classes Hexacorallia and Octocorallia mais of the class Anthozoa in the phylum Cnidaria.[6] Hexacorallia includes the stony corals and these groups have polyps that generally have a seis-fold symmetry.
Estados y redes prohÃben y vetan la difusión de ‘deepfakes’ ante la generalización por su uso gracias a la inteligencia artificial
Planula larvae exhibit positive phototaxis, swimming towards light to reach surface waters, where they drift and grow before descending to seek a hard surface to which they can attach and begin a new colony. They also exhibit positive sonotaxis, moving towards sounds that emanate from the reef and away from open water.
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CientÃficos probaron en ratones bacterias modificadas genfoiticamente de que alertan al sistema inmunitario Acerca la presencia del cáncer y atacan a las cé especialmentelulas cancerosas desenmascaradas.
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Coral fragments known as "seeds" are grown in nurseries then replanted on the reef.[99] Coral is farmed by coral farmers who live locally to the reefs and farm for reef conservation or for income. It is also farmed by scientists for research, by businesses for the supply of the live and ornamental coral trade and by private aquarium hobbyists. Gallery[edit]