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| Mussismilia | |
|---|---|
 | |
| Mussismilia hispida | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Cnidaria |
| Class: | Hexacorallia |
| Order: | Scleractinia |
| Family: | Mussidae |
| Genus: | Mussismilia Ortmann, 1890 [1] |
| Species | |
See text | |
Mussismilia is a colonial coral. Budding is always intracalicular, occurring inside the oral disc of the polyp, within the whorl of tentacles. The corallites are phaceloid or subplocoid, with irregular teeth or one to three centres being linked. When coenosteum is present, there is a distinctive double wall. The columella is discontinuous. The septa are porous and have unique, multi-directional teeth formed of twisted threads. The columella is spongy, and the columellar teeth are different in size and shape from the septal teeth. [2]
Mussismilia is a genus of stony corals in the subfamily Faviinae of the family Mussidae. This genus is restricted to the Atlantic Ocean off the coasts of Brazil.
Hexacorallia belong to the class Anthozoa, comprising organisms that form polyps with 6-fold symmetry, which includes all of the stony and reef-building corals.
Scleractinia are stony corals in the phylum Cnidaria and 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
Mussidae are a family of stony coral restricted to the Atlantic Ocean, they have a massive spheroid form with convolutions that resemble a brain. They are reef-building corals that are popular in captivity, but also the most vulnerable to coral bleaching and climate change
A family of stony reef-building corals that contain zooxanthellae, gaining energy from their symbionts as well as captured prey such as brine shrimp. They have massive colonies which can be in a phaceloid, plocoid, ceroid, or meandroid (rarely) shaped. They prefer intense sunlight and moderate water currents, especially since their preferred habitats are reef flats. They can tolerate dynamic environments, such as variations in salinity.
According to an analysis of the fossil record, Mussismilia used to be found all over the world. It is estimated that the genus originated between 23 million years ago to 400,000 years ago. However, currently, Mussismilia only occurs in South America’s Atlantic coastline.[9]
M. hispida has the widest geographic distribution of the four species of Mussismilia. This species reaches the Brazilian states of Maranhão, Rio Grande do Norte, Paraíba, Pernambuco, Alagoas, Sergipe, Bahia, Espírito Santo, Rio de Janeiro, and São Paulo, showing how expansive its reach is. It can also be found on farther-off oceanic coral reefs, like those of Fernando de Noronha Island and the Rocas Atoll.[5] The various species of Mussismilia are also found in specific geographic locations:
The World Register of Marine Species lists the following three species: [1]
Mussimilia braziliensis form massive colonies, which are usually large domes on reef tops. They have a cerioid colony form with an irregular shape and are around 8–10 mm in diameter. Septa of living colonies have rounded, bead-like dentations. These species are commonly blue-grey, green, and yellow in color and live in shallow or subtidal reef environments around Brazil. Due to the unique structural composition of M. braziliensis, organisms such as T. hirsutus crabs depend on the coral for habitat compared to the other Mussismilia species.
Mussismilia harttii (Verrill, 1868)
Mussismilia hartti has a phaceloid colony form and has calice diameters of 12–30 mm with 12–14 thin septa per cm. It is observed to have a greater crustacean fauna richness compared to the other species of Mussismilia due to its large meandroid pattern, in which polyps are larger and grow apart.
Mussismilia hispida (Verrill, 1901)
Mussismilia hispida colonies are massive colonies, less than 0.5 meters across, and usually flat. They are round with thick walls, which are around 10–15 mm in diameter. Septa of living colonies have rounded, bead-like teeth. These species are brown and grey in color, usually with different colored walls and centers with radial stripes. They live in shallow water and can tolerate unstable environments, making them more adaptable to the changing climate.
Mussismilia leptophylla
Initially, this species was placed in the genus Favia because it was thought to lack multiple trabecular fan systems which are commonly found in Mussismilia. However, researchers have found that Mussismilia leptophylla do contain more than one fan system and additional features in common with Mussismilia than Favia, including its parathecal wall structure and the shape of its septal teeth and microstructure. Its mitochondrial structure also groups it more closely with Mussismilia.
colony form: phaceloid or subplocoid
calice: Species of Mussismilia differ in colony form and calice size
Septa: thin and often porous near the columella
columella: continuous with trabecular linkage between centres.
corallite wall: parathecal wall
Septa: regular lacerate (twisted and multidirectional), spine-shaped porous granulation
Columella: spongy, and vary in size and shape from septal teeth
Wall: Parathecal (which is a Corallite wall formed by dissepiments or divisions in the tissue), along with calcifications in the wall
Mussismilia are mixotrophic organisms, meaning they rely on both photoautotrophy and heterotrophy for their feeding behavior, as was found through observation of fatty acid concentration and microalgae concentration in the host tissue of the species M. hispida.[9] Their state of being predominantly autotrophic or predominantly heterotrophic shifted many times over the year the study was conducted. Mussismilia also lives in symbiosis with dinoflagellate, photosynthetic algae that live within their tissue. The dinoflagellate uses sunlight to make sugar which results in energy that the corals can use. Mussismilia can also be heterotrophic, capturing and digesting zooplankton.
According to a live coral predation study conducted by Francini-Filho et al. (2008), Brazilian endemic parrotfish species, Scarus trispinosus and Sparisoma amplum, preyed mainly on M. braziliensis and F. gravida.[5] The study further accounted for bites that were allocated to live corals Sc. trispinosus (0.8% of bites) and Sp. amplum (8.1% of bites). Of 17 recorded predations, Sp. amplum preyed on M. braziliensis most frequently (n=15) in the Timbebas Reef of Brazil.[5]
The most abundant bacterium found in healthy Mussismilia corals include Alphaproteobacteria, Gammaproteobacteria, Cyanobacteria, Bacteroidetes, and Firmicute. Diseased corals were found to have a distinct microbiota, dominated by Bacteroidetes, Gammaproteobacteria, and unclassified Proteobacteria. The most abundant groups in the bare skeleton (SK) were Deltaproteobacteria, Alphaproteobacteria,, and Gammaproteobacteria, with a greater amount of Vibrios and Sulfate-Reducing Bacteria compared to healthy corals.
Three species of Mussismilia (M. braziliensis, M. hartti, and M. hispida) exhibit annual reproduction cycles with an average length of 11 months. These species are hermaphroditic species, with gamete development occurring at varying times among the species during the same breeding season.[15] These Mussismilia species are broadcast spawners, as no gonochoric colonies, embryos or planulae are observed. As broadcast spawners, Mussumilia release their gametes into the open ocean for external fertilization. Research suggests that spawner corals, specifically M hispida, can transmit their bacterial core to their offspring via their gametes, influencing the evolution of the future generations.[15]
Oogenesis begins several months before spermatogenesis. The organ in which spermatozoa is produced occurs during the eighth month of ovary development. As a result, both organs matured at the same time.
Oocyte development: During each developmental stage of oogenesis, a singular mesentery contains oocytes of varying-sized diameters. Initially, the nucleus was found in the central portion of the cell; however, it migrated to the border of the cell as the oocytes attained their maximum development. Mature oocytes appear irregular, but roughly spherical.
Spermaries development: During spermatogenesis, cells are in the endoderm of mesenteries, and then begin to concentrate. Like in oogenesis, the spermatic cells develop inside the same mesenteries. The nuclei become more visible. More mature cells are centrally located while those that are not are located peripherally.
When the spermatic cysts and eggs achieve maturity, the mesentery wall ruptures, allowing the bundles of spermatic cysts, eggs, and mucus to travel through the mouth and into the gastrovascular cavity, ultimately reaching the surface.[15]
Spawning: Each species has at least one spawning period, but it is possible to have two spawning periods within the reproductive cycle. The spawning period of M. hartti significantly differs from that of M. braziliensis and M. hispida. However, the period of spawning has occurred during different months across many studies.[10,15]
Mature corals release their gametes into the water column allowing for external fertilization to occur (meiosis). Once the egg is fertilized, it begins to develop. The fertilized egg, a zygote, then drifts into the current. During this drift, the zygote undergoes cell division (mitosis). Two cells form after the first division, and these cells undergo mitosis. Multiple divisions occur ultimately resulting in an embryo.
A planktonic planula larva forms. The planula uses its cilia to move to find a solid substrate to settle on. Once settled, metamorphosis begins (the juvenile develops into an adult). The juvenile polyp lays down a calcium carbonate corallite. When the adult polyp is sexually mature, the life cycle repeats.[16]
Some corals move in time to the current, but others such as Mussimilia have rock-like skeletons, so movements are not clearly visible. Researchers used a novel analysis imaging method to shoot photos of rocky corals to track their movements. They found that most activities occurred under nocturnal conditions including movement for tissue growth and polyp movement. While Mussismilia are stationary for the entirety of their lives, they do have subtle movements required to extend their polyps and capture zooplankton prey. However, it turns out that young corals are surprisingly mobile, moving with the ocean currents, though it is not entirely certain how Mussismilia larvae move.
Mussismilia, like many species of coral, are threatened by climate change and are particularly in danger of becoming extinct. The overall numbers of Mussismilia are hard to determine but shifts in the Earth’s climate has caused a gradual decrease in the numbers of Mussismilia ever since roughly the late 1900s. [2] It is hard to determine the exact time that recent global change started to negatively impact Mussismilia. Coral reefs lie primarily in shallow waters which are warmer than deeper waters. The sunlight does not reach the deeper areas of the ocean. Since the sunlight causes shallow waters to increase in temperature, coral reefs risk of bleaching increases. Bleaching occurs when corals expel the algae living in their tissues which causes the coral to turn white and their chances of survival dramatically decrease. Mussismilia are subject to coral bleaching in warm waters, and as world temperatures increase, Mussismilia can die. Mussismilia are capable of surviving and reproducing during bleaching events but their survival is severely hindered.
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.
A corallite is the skeletal cup, formed by an individual stony coral polyp, in which the polyp sits and into which it can retract. The cup is composed of aragonite, a crystalline form of calcium carbonate, and is secreted by the polyp. Corallites vary in size, but in most colonial corals they are less than 3 mm (0.12 in) in diameter. The inner surface of the corallite is known as the calyx. The vertical blades inside the calyx are known as septa and in some species, these ridges continue outside the corallite wall as costae. Where there is no corallite wall, the blades are known as septocostae. The septa, costae and septocostae may have ornamentation in the form of teeth and may be thick, thin or variable in size. Sometimes there are paliform lobes, in the form of rods or blades, rising from the inner margins of the septa. These may form a neat circle called the paliform crown. The septa do not usually unite in the centre of the corallite, instead they form a columella, a tangled mass of intertwined septa, or a dome-shaped or pillar-like projection. In the living coral, the lower part of the polyp is in intimate contact with the corallite, and has radial mesenteries between the septa which increase the surface area of the body cavity and aid digestion. The septa, palliform lobes and costae can often be seen through the coenosarc, the layer of living tissue that covers the coenosteum, the part of the skeleton between the corallites.
Mussidae is a family of stony coral in the order Scleractinia. Following a taxonomic revision in 2012, the family is now restricted to species found in the Atlantic Ocean, with Pacific species transferred to the new family Lobophylliidae. Many species are referred to as brain coral because their generally spheroid form and grooved surface resembles the convolutions of a brain.
Favia is a genus of reef-building stony corals in the family Mussidae. Members of the genus are massive or thickly encrusting colonial corals, either dome-shaped or flat, and a few are foliaceous. There is a great diversity of form even among individuals of the same species. The corallites project slightly above the surface of the coral and each has its own wall. In most species, the corallites are plocoid and in some, monocentric. The septa and costae linked to the corallite wall are well developed and covered by fine teeth. The polyps only extend and feed during the night. Each one has a small number of tapering tentacles which often have a darker coloured tip; these are called stinger tentacles, or sweeper tentacles. They use these to sweep the water to see if any other coral is in its area; if so, then they begin to sting the other coral. This is commonly known as coral war. Each coral is trying to make sure it has enough room around it so it can continue to grow and have more surface area for its offspring. The columella is parietal and spongy, and there are vesicles on both the endotheca and exotheca. Members of this genus are widespread in both the Atlantic Ocean and the Indo-Pacific.
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.
Stylophora pistillata, commonly known as hood coral or smooth cauliflower coral, is a species of stony coral in the family Pocilloporidae. It is native to the Indo-Pacific region and is commonly used in scientific investigations.
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.
Dichocoenia is a monotypic genus of stony coral in the family Meandrinidae. It is represented by a single species, Dichocoenia stokesii, which is commonly known as pineapple coral, elliptical star coral, or pancake star coral. It is mostly found in the Caribbean Sea and the western Atlantic Ocean. Dichocoenia stokesii has irregular calyces and its form can be either a massive, hemispherical hump or a flat, platform-like structure.
Isophyllia sinuosa, the sinuous cactus coral, is a species of stony coral in the family Mussidae. It is found in shallow water in the tropical western Atlantic and the Caribbean Sea.
Mussa is a genus of stony coral in the family Faviidae. It is monotypic, being represented by the single species Mussa angulosa, commonly known as the spiny or large flower coral. It is found on reefs in shallow waters in the Caribbean Sea, the Bahamas and the Gulf of Mexico.
Micromussa lordhowensis, previously known as the Acan Lord, is a species of stony coral in the family Lobophylliidae. It is a widespread and common coral with large polyps occurring on shallow reefs in the Indo-Pacific Ocean. It was originally classified under the genus Acanthastrea, and reclassified under the genus Micromussa in 2016.
Lobophyllia hemprichii, commonly called lobed brain coral, lobed cactus coral or largebrain root coral, is a species of large polyp stony coral in the family Lobophylliidae. It is found in the Indo-Pacific Ocean. In its specific name Christian Gottfried Ehrenberg honoured his late partner the Prussian naturalist Wilhelm Hemprich; they were among the first to study the marine life of the Red Sea.
Cynarina lacrymalis is a species of stony coral in the family Lobophylliidae. It is variously known as the flat cup coral, solitary cup coral, button coral, doughnut coral, or cat's eye coral. It is found in the western Indo-Pacific Ocean and is sometimes kept in reef aquaria.
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.
Coelastrea aspera is a species of stony coral in the family Merulinidae. It is a colonial species native to the Indo-Pacific region where it occurs in shallow water. It was first described by the American zoologist Addison Emery Verrill in 1866 as Goniastrea aspera but it has since been determined that it should be in a different genus and its scientific name has been changed to Coelastrea aspera. This is a common species throughout much of its wide range and the International Union for Conservation of Nature has rated its conservation status as being of "least concern".
Agaricia agaricites, commonly known as lettuce coral or tan lettuce-leaf coral, is a species of colonial stony corals in the family Agariciidae. This coral is found in shallow waters in the tropical western Atlantic Ocean and the Caribbean Sea. The IUCN has assessed its status as being Vulnerable.
Favites complanata is a species of stony coral in the family Merulinidae, sometimes known as the larger star coral. It is native to the Indo-Pacific region and its range extends from the Red Sea and Indian Ocean to the western and central Pacific Ocean. This is an uncommon species of coral and seems to be decreasing in abundance, and the International Union for Conservation of Nature has rated its conservation status as being "near threatened".
Euphylliidae are known as a family of polyped stony corals under the order Scleractinia.
Manicina areolata, commonly known as rose coral, is a colonial species of stony coral. It occurs in shallow water in the West Atlantic Ocean and Caribbean Sea, sometimes as small solid heads and sometimes as unattached cone-shaped forms.
Tubastraea faulkneri, common name Orange sun coral, is a species of large-polyp stony corals belonging to the family Dendrophylliidae. Other common names of this coral are Orange Cup Coral, Sun Coral, Orange Polyp Coral, Rose Sun Coral, Golden Cup Coral, Sun Flower Coral, and Tube Coral.