Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.
A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups.
Coral bleaching is the process when corals become white due to loss of symbiotic algae and photosynthetic pigments. This loss of pigment can be caused by various stressors, such as changes in temperature, light, or nutrients. Bleaching occurs when coral polyps expel the zooxanthellae that live inside their tissue, causing the coral to turn white. The zooxanthellae are photosynthetic, and as the water temperature rises, they begin to produce reactive oxygen species. This is toxic to the coral, so the coral expels the zooxanthellae. Since the zooxanthellae produce the majority of coral colouration, the coral tissue becomes transparent, revealing the coral skeleton made of calcium carbonate. Most bleached corals appear bright white, but some are blue, yellow, or pink due to pigment proteins in the coral.
A microatoll is a circular colony of coral, dead on the top but living around the perimeter. Growth is mainly lateral, as upward growth is limited by exposure to air. Microatolls may be up to 6 meters (20 ft) in diameter. They are named for their resemblance to island atolls formed during the subsidence of volcanic islands, as originally suggested by Darwin (1842).
Spirobranchus giganteus, commonly known as the Christmas tree worm, is a tube-building polychaete worm belonging to the family Serpulidae. The S. giganteus lives in coral reefs in the Indo-Pacific region to the Caribbean.
Elkhorn coral is an important reef-building coral in the Caribbean. The species has a complex structure with many branches which resemble that of elk antlers; hence, the common name. The branching structure creates habitat and shelter for many other reef species. Elkhorn coral is known to grow quickly with an average growth rate of 5 to 10 cm per year. They can reproduce both sexually and asexually, though asexual reproduction is much more common and occurs through a process called fragmentation.
Porites astreoides, commonly known as mustard hill coral or yellow porites, is a colonial species of stony coral in the family Poritidae.
Porites lobata, known by the common name lobe coral, is a species of stony coral in the family Poritidae. It is found growing on coral reefs in tropical parts of the Indian and Pacific Oceans.
Porites porites, commonly known as hump coral or finger coral, is a species of stony coral in the genus Porites. It is found in the Caribbean Sea and western Atlantic Ocean and also along the coast of West Africa.
Porites furcata, commonly known as hump coral, thin finger coral or branched finger coral, is a species of stony coral in the genus Porites. It is found in the Caribbean Sea and western Atlantic Ocean.
Porites nodifera, also known as dome coral, is a species of stony coral in the Poritidae family.
Porites cylindrica, commonly known as Hump coral, is a stony coral belonging to the subclass Hexacorallia in the class Anthozoa. Hexacorallia differ from other subclasses in that they have six or fewer axes of symmetry. Members of this class possess colonial polyps which can be reef-building, secreting a calcium carbonate skeleton. They are dominant in both inshore reefs and midshelf reefs.
Ocean acidification threatens the Great Barrier Reef by reducing the viability and strength of coral reefs. The Great Barrier Reef, considered one of the seven natural wonders of the world and a biodiversity hotspot, is located in Australia. Similar to other coral reefs, it is experiencing degradation due to ocean acidification. Ocean acidification results from a rise in atmospheric carbon dioxide, which is taken up by the ocean. This process can increase sea surface temperature, decrease aragonite, and lower the pH of the ocean. The more humanity consumes fossil fuels, the more the ocean absorbs released CO₂, furthering ocean acidification.
Pocillopora capitata, commonly known as the Cauliflower coral, is a principal hermatypic coral found in the Eastern Tropical Pacific. P. capitata is a colonial species of stony coral of the class Anthozoa, the order Scleractinia, and the family Pocilloporidae. This species was first documented and described by Addison Emery Verrill in 1864. P. capitata is threatened by many of the effects of climate change, including — but not limited to — increased temperatures that cause bleaching and hypoxic conditions.
Clathria aceratoobtusa is a species of sponge in the family Microcionidae. The genus Clathria is subdivided into a number of subgenera, and it is in the subgenus Microciona. It is native to shallow water habitats in the Indo-Pacific region. The type locality is the Gulf of Thailand.
Porites lutea is a species of stony coral in the family Poritidae. It is found growing in very shallow water on reefs in the Indo-Pacific region. It sometimes forms "microatolls" in the intertidal zone and these massive structures have been used to study trends in sea levels and sea water temperature.
An electric reef is an artificial reef made from biorock, being limestone that forms rapidly in seawater on a metal structure from dissolved minerals in the presence of a small electric current. The first reefs of this type were created by Wolf Hilbertz and Thomas J. Goreau in the 1980s. By 2011 there were examples in over 20 countries.
Pavona varians, also known by its common name corrugated coral, is a species from the genus Pavona. Pavona varians is a type of hermatypic coral commonly distributed across tropic environments. Distribution of the coral include the equatorial Indian and Pacific Ocean, and notably, not found in the Atlantic Ocean. Pavona varians have also been found to be distributed as North as the sea of Japan, in the Red Sea, and islands off the Pacific coast of Columbia and Costa Rica. Pavona varians are typically found an average of 45 feet below water on vertical surfaces in turbid, nutrient rich, water. Specifically, Pavona varians are found between crevices of the reef crest habitats and back reef habitats, including lagoons.
Flinders Reef or Flinders Reefs is an isolated oceanic coral reef in the Coral Sea of the western Pacific Ocean. It lies east of Australia and the extensive Great Barrier Reef. Due to its remote location, it remains poorly studied. However, this isolation has also made it a potential site to mark the beginning of the Anthropocene.
Spirobranchus corniculatus, commonly referred to as the Indo-Pacific Christmas tree worm, is a species of tube-building annelid fanworms in the family Serpulidae. Belonging to the class Polychaeta, it is recognized for its bristle-like tentacles and the presence of a structure called radioles. It is widely encountered and recognized for its unique resemblance to a conifer and its diverse array of colors. Initially presumed to be part of a species group including Spirobranchus cruciger and Spirobranchus gaymardi, it has been determined to be a singular, morphologically adaptable species inhabiting the Central Indo-Pacific region.
