What is the difference between hard coral and soft coral?

What is the difference between hard coral and soft coral?

Corals are marine (saltwater) invertebrate animals that usually form colonies of individual polyps, mainly in tropical reefs. 

Hard coral is also called stony coral.

Hard coral is in the sub-class Hexacorallia (hexa means six), whereas bue coral and soft coral are in the sub-class Octocorallia (octo means eight).

Hard coral is in the Scleractinia order, whereas soft coral is in the Alyconacea order.

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Highest levels of coral cover in the Great Barrier Reef in 36 years but the ecosystem remains vulnerable

Scientists at the Australian Institute of Marine Sciences (AIMS) have stated that the coral cover in Australia’s Great Barrier Reef is the highest ever recorded, since records began 36 years ago, but the ecosystem remains vulnerable. 

The Great Barrier Reef on the eastern coast of Australia is the world’s largest natural reef system of over 2,900 individual reefs and 900 islands over 2,300 kilometres (1,400 miles) long. It was listed as a UNESCO World Heritage Site in 1981 and labelled one of the seven natural wonders of the world in 1997. 

AIMS scientists have been monitoring the levels of coral coverage in the reef to determine its health. They publish their findings annually. 

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Bubble Coral

The Bubble Coral (Plerogyra sinuosa) is a marine (saltwater) zooxanthellate coral in the Caryophylliidae family of stony corals, although this is not definitive according to some zoologists – they refer to its classification as Incertae sedis or Problematica (which means ‘uncertain placement’ or ‘problematic’). It is in the Cnidaria phylum. It is also known as Grape Coral, Pearl Coral, and Bladder Coral. 

The Bubble Coral ‘bubble’ is grape-sized and roundish. It is cream to yellowish to light beige. Bunched together, like grapes, they form a colony that looks like an inverted cone. 

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RESEARCH: Dolphins May Be Able to Heal their Own Wounds

Do dolphins heal their own wounds?

Scientists think that dolphins rub against coral to treat wounds on their skin. The New Scientist magazine in May 2022 explained that Bottlenose Dolphins appear to look for specific corals and sea sponges that produce anti-bacterial or hormone-like substances, which may indicate that they are trying to heal their own wounds and infections by rubbing against them.  

Scientists have observed orcas and Beluga whales rubbing their bodies against underwater sand and pebbles, but similar behaviour in dolpins has not been widely observed.

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Warty Gorgonian Coral

The Warty Gorgonian (Eunicella verrucosa) is a soft marine (saltwater) coral in the Gorgoniidae family of sea fans. It is also known as the Broad Sea Fan Coral and the Pink Sea Fan Coral. It is not a plant.

The Warty Gorgonian is a branching calcareous coral. It branches into slender, warty stems and branchlets. The warts are small growths. It can be red, pink, or white. It leans in the direction of the water flow or ocean current. The polyps emerge from the warty protrusions and spread their tentacles to feed on organisms in the sea. The polyps are retractable with eight tentacles.

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Knobby Finger Coral

The Knobby Finger Coral (Porites duerdeni) is a marine (saltwater) coral in the Poritidae family of polyp stony corals.

The Knobby Finger Coral looks like short, stubby, branching fingers in small, mound-shaped colonies. The top of each finger is spherical. It has widely spaced calices with retracted polyps. It has a well-developed wall reticulum. It can be varied in colour from light grey to yellowish-green and pinkish-red. It is sessile (not moving), with a mouth in each polyp.

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Coral Reef Found Off Tahiti in the Twilight Zone

A coral reef has been found in deep water off the coast of Tahiti in the Pacific Ocean. The coral reef was found to be pristine, undamaged, and in good environmental health. 

The coral reef is rose-shaped. It is part of a larger reef that stretches for more than 3 kilometres long and 70 metres wide at its widest point.  

Laetitia Hédouin and her colleagues at the National Centre for Scientific Research in France undertook diving expeditions off the coast of Tahiti and found the reef. Hédouin said it was a very healthy reef, ‘like a dream come true.’

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Pulsing Coral

The Pulsing Coral (Xenia sp.) is a soft marine (saltwater) coral in the Xeniidae family. It is also known as Pulse Coral. It is not a plant.

The Pulsing Coral resembles a mat-like mushroom with many-fingered arms. It uses its polyp arms to move water around it. This is called pulsatile motion. It is an octocoral because it has eight tentacles and eight mesenteries on their polyps. It can be white, yellow, blue, green, and brown.

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Jewel Anemone

The Jewel Anemone (Corynactis viridis) is a marine (saltwater) anthozoan cnidarian in the Corallimorphidae family of sea anemones. It is an animal, not a plant. 

The Jewel Anemone is cylindrical, slightly wider at the base, with an oral (mouth) disc and polyps. The individual polyps are clustered in aggregations. It is not attached to the soil or rock – the individuals can detach and drift away. Its tentacles are short, althought the outer tentacles are longer than the inner tentacles. Its colour is variable, but it is mainly white, pink, orange, red, and green.

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CREATURE FEATURE: Solitary Disk Coral

The Solitary Disk Coral (Scolymia cubensis) is a solitary marine (saltwater) stony coral in the Mussidae family. It is not a plant.

The Solitary Disk Coral is flat and concave with a circular shape, like an inverted cone. It can be light-green, beige, or deep rusty red. It has layers of thick plates called septa that surround a central mouth with spongy polyps.

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Sea Fan Coral

The Sea Fan Coral (Pinnigorgia sp.) is a marine (saltwater) soft coral in the Gorgoniidae family of sea fans. It is not a plant. 

The Sea Fan Coral has calcareous spicules (horny nodules) on branchlets. The branchlets are usually slender. It can be whiplike, bushy, or spread out like a fan. The polyps are retractable with eight tentacles. It can be purple, red, or yellowish.

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Plate Coral

The Plate Coral (Lithophyllon repanda or Fungia repanda) is a large marine (saltwater) polyp stony coral in the Fungiidae family of mushroom, disc, or plate coral. It is not a plant. It is also called the Mushroom Coral and the Fungia Plate Coral.

The Plate Coral is a colony of organisms, each with a separate mouth. It is shaped like a plate with a round, flat body, which is raised a little in the centre where the mouth is. It is covered with short tentacles, less than 2 centimetres (less than an inch) in height. It can be a variety of colours, from brownish to yellow, red, blue, or orange.

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Red Coral

The Red Coral (Corallium rubrum formally Gorgonia nobilis) is a marine (saltwater) coral in the Corallidae family of branched limestone coral. It is also called Precious Coral. Coral is an animal, not a plant.

The Red Coral is red or pink-orange. It has branches, made from calcium carbonate, that are tree-like. It has retractable transparent white polyps with a round mouth disc surrounded by eight hollow tentacles. The tentacles have mild venom (poison). It is sessile (it does not move). 

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Yellow Cluster Anemone

The Yellow Cluster Anemone (Parazoanthus axinellae) is a marine (saltwater) zoanthid coral in the Parazoanthidae family. It is also known as the Sea Mimosa. It is an animal, not a plant.

The Yellow Cluster Anemone is yellow or orange.  It is a cluster of individual polyps connected by a tissue called coenenchyme. Each polyp has 24-36 tentacles in two whorls. The polyps retract into their tube when threatened.

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Elegance Coral

The Elegance Coral (Catalaphyllia jardinei) is a marine (saltwater) photosynthetic coral in the Euphyllidae family of stony coral. It is also known as the Wonder Coral or the Ridge Coral. It is an animal, not a plant.

The Elegance Coral has large polyps with a large, branching coralite skeleton. The polyps have long tendrils and a large, fleshy, disc-shaped (round) mouth. It can be fluorescent green, lime green, and brown.

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Blue Coral

The Blue Coral (Heliopora coerulea) is a species of hard marine (saltwater) coral in the Helioporidae family of octocorals. It is an animal, not a plant.

The Blue Coral has a blue skeleton made of calcium carbonate. Often it is hidden by individual greenish-grey or blue polyps that live in tubes within the skeleton. Each polyp has eight tentacles.

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Yellow Scroll Coral

The Yellow Scroll Coral (Turbinaria reniformis) is a marine (saltwater) invertebrate in the Dendrophyllidae family of stony coral. It is an animal, not a plant.

The Yellow Scroll Coral is usually yellow or yellowish-green. It is a laminar (plate-like) species that forms horizontal plates or shallow chalices (cup-shapes) with thick walls. The skeletal cups are called coralites. The plates form a stony skeleton. Polyps protrude from the skeleton. The polyps have a central mouth disc with eight tentacles around the circular disc. 

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