Halofolliculina corallasia
Encyclopedia
Halofolliculina corallasia is a heterotrich
ciliate
identified as a cause of the syndrome called Skeletal Eroding Band
(SEB). It is the first coral disease pathogen that is a protozoan as well as the first known to be an eucaryote; all others identified are bacteria
. Like other members of the folliculinid family
, H. corallasia is sessile
and lives in a "house" called a lorica
, into which the cell can retreat when disturbed. The mouth is flanked by a pair of wing-like projections that are fringed with polykinetids, groups of cilia that work in groups to produce a current that draws food into the "mouth".
This species is so far the only known agent causing Skeletal Eroding Band
, the most common disease of coral
s in the Indian
and Pacific Ocean
s, and also found in the Red Sea
. A very similar disease was later discovered in the Caribbean Sea
, but is caused by a different species of the same genus
and occurs in a different type of environment.
in 1988, and named in 2001. The species name corallasia is a combination of "coral" and the Greek
word lasios (λάσιος), which means "densely overgrown". H. corallasia is a member of the folliculinid family
of heterotrich
ciliate
protozoa
ns. A ciliates is among the most complex of single-celled eucaryote organisms, distinguished by three characteristics.
First, it reproduces both by cell division
(splitting one cell into two) and by conjugation, in which two organisms temporarily join in order to swap DNA.
Second, it has two cell nuclei
. The larger, called the "macronucleus", carries out the normal work of the cell by transcribing
DNA
into RNA
, which is used to control the cell's functions. The smaller "micronucleus" is used only for reproducing the organism by cell division and by conjugation.
And third, it has cilia at some stage in its life cycle.
Heterotrichs, which are among the largest protozoans, have a spiral of polykinetids around their "mouths". These are groups of cilia that work in groups to produce a current that draws food into the "mouth". Members of the heterotrich family Folliculinidae are sessile
, enclosing the rear ends in a lorica
(Latin
for cuirass
, flexible body armor) that is anchored to a surface, and into which the cells retract when disturbed. The mouth is flanked by a pair of wing-like projections that are fringed with polykinetids. H. corallasia is smaller than other members of the same genus, having a flask-shaped lorica typically 0.22 millimetre (0.00866141732283465 in) long and 0.095 millimetre (0.00374015748031496 in) wide, and "wings" that are 0.175 to 0.2 mm (0.00688976377952756 to 0.0078740157480315 in) long when fully extended. Its lorica, which is dark gray or black and made of a chitin
-like substance, has flaps that close its opening when the cell is retracted.
and Pacific Ocean
s and also found in the Red Sea
, is the first recorded disease of coral
s that is caused by a protozoan, and the first caused by a eucaryote – most are caused by bacteria
. The disease is visible as a black band that slowly advances over corals, leaving dead coral in its wake. It is spread by cell division of Halofolliculina corallasia, which produces a pair of worm-like larva
e that settle on undamaged coral just ahead of the black band. There each secretes
its lorica, at the same spinning to produce the lorica's flask-like shape. This spinning, combined with the chemicals that harden the lorica, crumble the coral skeleton
and kill the polyp
s. The discarded loricae of the "parent" H. corallasia cells remain, leaving a spotted region in the wake of the living black band. This distinguishes Skeletal Eroding Band from Black band disease
, which leaves a completely white dead area behind it. H. corallasia is the first protozoan and the first eucaryote that is known to cause a disease in corals.
A survey in the Caribbean Sea
conducted in 2004 and published in 2006 reported a disease with very similar symptoms as SEB, affecting 25 species of coral within 6 families. Although the authors initially suspected H.corallasia, more detailed examination showed that the culprit was another species that was previously unknown and has not yet been formally named, although it is clearly a member of the same genus
, Halofolliculina. A follow-up analysis noted that the Caribbean infestations were most common in oceanic waters, while those in the Indian and Pacific Oceans were more prevalent in coastal waters. Its authors therefore gave this new manifestation the name "Caribbean ciliate infection".
Heterotrich
The heterotrichs are a class of ciliates. They typically have a prominent adoral zone of membranelles circling the mouth, used in locomotion and feeding, and shorter cilia on the rest of the body. Many species are highly contractile, and are typically compressed or conical in form...
ciliate
Ciliate
The ciliates are a group of protozoans characterized by the presence of hair-like organelles called cilia, which are identical in structure to flagella but typically shorter and present in much larger numbers with a different undulating pattern than flagella...
identified as a cause of the syndrome called Skeletal Eroding Band
Skeletal Eroding Band
Skeletal eroding band is a disease of corals that appears a black or dark gray band that slowly advances over corals, leaving a spotted region of dead coral in its wake...
(SEB). It is the first coral disease pathogen that is a protozoan as well as the first known to be an eucaryote; all others identified are bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
. Like other members of the folliculinid family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
, H. corallasia is sessile
Sessility (zoology)
In zoology, sessility is a characteristic of animals which are not able to move about. They are usually permanently attached to a solid substrate of some kind, such as a part of a plant or dead tree trunk, a rock, or the hull of a ship in the case of barnacles. Corals lay down their own...
and lives in a "house" called a lorica
Lorica (biology)
In biology, a lorica is a shell-like protective outer covering, often reinforced with sand grains and other particles that some protozoans and loricifera metazoans secrete. Usually it is tubular or conical in shape, with a loose case that is closed at one end. An example is the protozoan genus...
, into which the cell can retreat when disturbed. The mouth is flanked by a pair of wing-like projections that are fringed with polykinetids, groups of cilia that work in groups to produce a current that draws food into the "mouth".
This species is so far the only known agent causing Skeletal Eroding Band
Skeletal Eroding Band
Skeletal eroding band is a disease of corals that appears a black or dark gray band that slowly advances over corals, leaving a spotted region of dead coral in its wake...
, the most common disease of coral
Coral
Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...
s in the Indian
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
and Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
s, and also found in the Red Sea
Red Sea
The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...
. A very similar disease was later discovered in the Caribbean Sea
Caribbean Sea
The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles, and to the east by the Lesser Antilles....
, but is caused by a different species of the same genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
and occurs in a different type of environment.
Description
Halofolliculina corallasia was first observed in reefs near Motupore Island in Papua New GuineaPapua New Guinea
Papua New Guinea , officially the Independent State of Papua New Guinea, is a country in Oceania, occupying the eastern half of the island of New Guinea and numerous offshore islands...
in 1988, and named in 2001. The species name corallasia is a combination of "coral" and the Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
word lasios (λάσιος), which means "densely overgrown". H. corallasia is a member of the folliculinid family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of heterotrich
Heterotrich
The heterotrichs are a class of ciliates. They typically have a prominent adoral zone of membranelles circling the mouth, used in locomotion and feeding, and shorter cilia on the rest of the body. Many species are highly contractile, and are typically compressed or conical in form...
ciliate
Ciliate
The ciliates are a group of protozoans characterized by the presence of hair-like organelles called cilia, which are identical in structure to flagella but typically shorter and present in much larger numbers with a different undulating pattern than flagella...
protozoa
Protozoa
Protozoa are a diverse group of single-cells eukaryotic organisms, many of which are motile. Throughout history, protozoa have been defined as single-cell protists with animal-like behavior, e.g., movement...
ns. A ciliates is among the most complex of single-celled eucaryote organisms, distinguished by three characteristics.
First, it reproduces both by cell division
Cell division
Cell division is the process by which a parent cell divides into two or more daughter cells . Cell division is usually a small segment of a larger cell cycle. This type of cell division in eukaryotes is known as mitosis, and leaves the daughter cell capable of dividing again. The corresponding sort...
(splitting one cell into two) and by conjugation, in which two organisms temporarily join in order to swap DNA.
Second, it has two cell nuclei
Cell nucleus
In cell biology, the nucleus is a membrane-enclosed organelle found in eukaryotic cells. It contains most of the cell's genetic material, organized as multiple long linear DNA molecules in complex with a large variety of proteins, such as histones, to form chromosomes. The genes within these...
. The larger, called the "macronucleus", carries out the normal work of the cell by transcribing
Transcription (genetics)
Transcription is the process of creating a complementary RNA copy of a sequence of DNA. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes...
DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
into RNA
RNA
Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....
, which is used to control the cell's functions. The smaller "micronucleus" is used only for reproducing the organism by cell division and by conjugation.
And third, it has cilia at some stage in its life cycle.
Heterotrichs, which are among the largest protozoans, have a spiral of polykinetids around their "mouths". These are groups of cilia that work in groups to produce a current that draws food into the "mouth". Members of the heterotrich family Folliculinidae are sessile
Sessility (zoology)
In zoology, sessility is a characteristic of animals which are not able to move about. They are usually permanently attached to a solid substrate of some kind, such as a part of a plant or dead tree trunk, a rock, or the hull of a ship in the case of barnacles. Corals lay down their own...
, enclosing the rear ends in a lorica
Lorica (biology)
In biology, a lorica is a shell-like protective outer covering, often reinforced with sand grains and other particles that some protozoans and loricifera metazoans secrete. Usually it is tubular or conical in shape, with a loose case that is closed at one end. An example is the protozoan genus...
(Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
for cuirass
Cuirass
A cuirass is a piece of armour, formed of a single or multiple pieces of metal or other rigid material, which covers the front of the torso...
, flexible body armor) that is anchored to a surface, and into which the cells retract when disturbed. The mouth is flanked by a pair of wing-like projections that are fringed with polykinetids. H. corallasia is smaller than other members of the same genus, having a flask-shaped lorica typically 0.22 millimetre (0.00866141732283465 in) long and 0.095 millimetre (0.00374015748031496 in) wide, and "wings" that are 0.175 to 0.2 mm (0.00688976377952756 to 0.0078740157480315 in) long when fully extended. Its lorica, which is dark gray or black and made of a chitin
Chitin
Chitin n is a long-chain polymer of a N-acetylglucosamine, a derivative of glucose, and is found in many places throughout the natural world...
-like substance, has flaps that close its opening when the cell is retracted.
A threat to corals
Skeletal Eroding Band, the most common disease of corals in the IndianIndian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
and Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
s and also found in the Red Sea
Red Sea
The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...
, is the first recorded disease of coral
Coral
Corals are marine animals in class Anthozoa of phylum Cnidaria typically living in compact colonies of many identical individual "polyps". The group includes the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton.A coral "head" is a colony of...
s that is caused by a protozoan, and the first caused by a eucaryote – most are caused by bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
. The disease is visible as a black band that slowly advances over corals, leaving dead coral in its wake. It is spread by cell division of Halofolliculina corallasia, which produces a pair of worm-like larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e that settle on undamaged coral just ahead of the black band. There each secretes
Secretion
Secretion is the process of elaborating, releasing, and oozing chemicals, or a secreted chemical substance from a cell or gland. In contrast to excretion, the substance may have a certain function, rather than being a waste product...
its lorica, at the same spinning to produce the lorica's flask-like shape. This spinning, combined with the chemicals that harden the lorica, crumble the coral skeleton
Skeleton
The skeleton is the body part that forms the supporting structure of an organism. There are two different skeletal types: the exoskeleton, which is the stable outer shell of an organism, and the endoskeleton, which forms the support structure inside the body.In a figurative sense, skeleton can...
and kill the polyp
Polyp
A polyp in zoology is one of two forms found in the phylum Cnidaria, the other being the medusa. Polyps are approximately cylindrical in shape and elongated at the axis of the body...
s. The discarded loricae of the "parent" H. corallasia cells remain, leaving a spotted region in the wake of the living black band. This distinguishes Skeletal Eroding Band from Black band disease
Black band disease
Black band disease is characterized by complete coral tissue degradation due to a pathogenic microbial consortium that appears as a dark red or black migrating microbial mat. The mat is present between apparently healthy coral tissue and freshly exposed coral skeleton.-Appearance:Black Band disease...
, which leaves a completely white dead area behind it. H. corallasia is the first protozoan and the first eucaryote that is known to cause a disease in corals.
A survey in the Caribbean Sea
Caribbean Sea
The Caribbean Sea is a sea of the Atlantic Ocean located in the tropics of the Western hemisphere. It is bounded by Mexico and Central America to the west and southwest, to the north by the Greater Antilles, and to the east by the Lesser Antilles....
conducted in 2004 and published in 2006 reported a disease with very similar symptoms as SEB, affecting 25 species of coral within 6 families. Although the authors initially suspected H.corallasia, more detailed examination showed that the culprit was another species that was previously unknown and has not yet been formally named, although it is clearly a member of the same genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
, Halofolliculina. A follow-up analysis noted that the Caribbean infestations were most common in oceanic waters, while those in the Indian and Pacific Oceans were more prevalent in coastal waters. Its authors therefore gave this new manifestation the name "Caribbean ciliate infection".