Corals are marine invertebrates within the class 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.
Anthozoa is a class of marine invertebrates which includes the sea anemones, stony corals and soft corals. Adult anthozoans are almost all attached to the seabed, while their larvae can disperse as part of the plankton. The basic unit of the adult is the polyp; this consists of a cylindrical column topped by a disc with a central mouth surrounded by tentacles. Sea anemones are mostly solitary, but the majority of corals are colonial, being formed by the budding of new polyps from an original, founding individual. Colonies are strengthened by calcium carbonate and other materials and take various massive, plate-like, bushy or leafy forms.
Scleractinia, also called stony corals or hard corals, are marine animals in the phylum Cnidaria that build themselves a hard skeleton. The individual animals are known as polyps and have a cylindrical body crowned by an oral disc in which a mouth is fringed with tentacles. Although some species are solitary, most are colonial. The founding polyp settles and starts to secrete calcium carbonate to protect its soft body. Solitary corals can be as much as 25 cm (10 in) across but in colonial species the polyps are usually only a few millimetres in diameter. These polyps reproduce asexually by budding, but remain attached to each other, forming a multi-polyp colony of clones with a common skeleton, which may be up to several metres in diameter or height according to species.
The aggregating anemone, or clonal anemone, is the most abundant species of sea anemone found on rocky, tide swept shores along the Pacific coast of North America. This cnidarian hosts endosymbiotic algae called zooxanthellae that contribute substantially to primary productivity in the intertidal zone. The aggregating anemone has become a model organism for the study of temperate cnidarian-algal symbioses.
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.
Aiptasia is a genus of a symbiotic cnidarian belonging to the class Anthozoa. Aiptasia is a widely distributed genus of temperate and tropical sea anemones of benthic lifestyle typically found living on mangrove roots and hard substrates. These anemones, as well as many other cnidarian species, often contain symbiotic dinoflagellate unicellular algae of the genus Symbiodinium living inside nutritive cells. The symbionts provide food mainly in the form of lipids and sugars produced from photosynthesis to the host while the hosts provides inorganic nutrients and a constant and protective environment to the algae. Species of Aiptasia are relatively weedy anemones able to withstand a relatively wide range of salinities and other water quality conditions. In the case of A. pallida and A. pulchella, their hardiness coupled with their ability to reproduce very quickly and out-compete other species in culture gives these anemones the status of pest from the perspective of coral reef aquarium hobbyists. These very characteristics make them easy to grow in the laboratory and thus they are extensively used as model organisms for scientific study. In this respect, Aiptasia have contributed a significant amount of knowledge regarding cnidarian biology, especially human understanding of cnidarian-algal symbioses, a biological phenomenon crucial to the survival of corals and coral reef ecosystems. The dependence of coral reefs on the health of the symbiosis is dramatically illustrated by the devastating effects experienced by corals due to the loss of algal symbionts in response to environmental stress, a phenomenon known as coral bleaching.
Anemonia sulcata, or Mediterranean snakelocks sea anemone, is a species of sea anemone in the family Actiniidae from the Mediterranean Sea. Whether A. sulcata should be recognized as a synonym of A. viridis remains a matter of dispute.
Sea anemones are the marine, predatory animals of the order Actiniaria. They are named after the anemone, a terrestrial flowering plant, because of the colourful appearance of many. Sea anemones are classified in the phylum Cnidaria, class Anthozoa, subclass Hexacorallia. As cnidarians, sea anemones are related to corals, jellyfish, tube-dwelling anemones, and Hydra. Unlike jellyfish, sea anemones do not have a medusa stage in their life cycle.
Porites astreoides, commonly known as mustard hill coral or yellow porites, is a colonial species of stony coral in the family Poritidae.
Coral reef fish are fish which live amongst or in close relation to coral reefs. Coral reefs form complex ecosystems with tremendous biodiversity. Among the myriad inhabitants, the fish stand out as colourful and interesting to watch. Hundreds of species can exist in a small area of a healthy reef, many of them hidden or well camouflaged. Reef fish have developed many ingenious specialisations adapted to survival on the reefs.
Anthopleura xanthogrammica, or the giant green anemone, is a species of intertidal sea anemone of the family Actiniidae.
Millepora alcicornis, or sea ginger, is a species of colonial fire coral with a calcareous skeleton. It is found on shallow water coral reefs in the tropical west Atlantic Ocean. It shows a variety of different morphologies depending on its location. It feeds on plankton and derives part of its energy requirements from microalgae found within its tissues. It is an important member of the reef building community and subject to the same threats as other corals. It can cause painful stings to unwary divers.
Triactis is a genus of sea anemone in the family Aliciidae. It is monotypic, having only one species – Triactis producta. This is found in shallow waters in the Indo-Pacific where it lives on the seabed, rocks and corals. It derives much of its energy needs from the symbiotic algae it contains. It also forms a mutualistic relationship with small Lybia crabs.
Bartholomea annulata is a species of sea anemone in the family Aiptasiidae, commonly known as the ringed anemone or corkscrew anemone. It is one of the most common anemones found on reefs in the Caribbean Sea.
Scolymia lacera, the fleshy disk coral, is a species of stony coral in the family Mussidae. It occurs on reefs in shallow waters in the Caribbean Sea, the Gulf of Mexico, the Bahamas, Bermuda and southern Florida.
Phyllodiscus is a monotypic genus of sea anemones in the family Aliciidae. The only species is Phyllodiscus semoni, commonly known as the night anemone, which is native to shallow seas in the central Indo-West Pacific, such as Indonesia, the Philippines and southern Japan. It is venomous and can cause a painful, long-lasting sting to humans. It is called unbachi-isoginchaku in Japanese which translates as "wasp-sea anemone".
Lebrunia coralligens, commonly known as the hidden anemone, is a species of sea anemone in the family Aliciidae. It is found in shallow water in the Bahamas, the Caribbean, and Brazil. It lives in fissures in corals and rocks.
Dipsastraea speciosa is a species of colonial stony coral in the family Merulinidae. It is found in tropical waters of the Indian and Pacific oceans.
The thimble jellyfish is a species of cnidarian found in the warm West Atlantic Ocean, including the Caribbean. It is a tiny jellyfish with a straight-sided, flat-topped bell. This jellyfish is the most common cause of seabather's eruption, a reaction caused by the injection of juvenile jellyfish nematocysts into human skin.
Ricordea yuma is a species of coral in the family Ricordeidae, order Corallimorpharia; This order of corals do not produce the distinctive calcification of the closely related Scleractinian, or reef building corals. Ricordea yuma are found on the sea floor in relatively shallow, tropical or subtropical ocean environments. Distinctive features include a large mouth disk that takes up most of the organism, and brightly colored tentacles. Ricordea yuma can reproduce both sexually, and asexually by budding a new coral with replicated elements from the mother coral. This may be one mechanism of how they are able to spread and overtake areas rapidly; They have been observed being competitively successful at monopolizing areas by excluding reef-building coral species, after a disturbance in the substrate.
