Soil Ecology Wiki - User contributions [en]

Flavobacterium

2023-04-22T19:37:07Z

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2023-04-22T18:44:44Z

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File:Flavo Meningitis.jpg

2023-04-22T18:28:58Z

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File:Flavo Intro.jpg

2023-04-22T18:28:36Z

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2023-04-22T18:28:13Z

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Crustacean

2023-04-01T21:17:51Z

Jmcruz3:

{| class="wikitable" style="text-align:center; float:right; margin-left: 10px;
|+ !colspan="2" style="min-width:12em; text-align: center; background-color: rgb(235,235,210)|'''Taxonomic Classification'''
|-
|colspan="2" |[[File:Crustacea 1 - Range of crustacean appearance.jpeg|400px|caption]]
|-
!style="min-width:6em; |Kingdom:
|style="min-width:6em; |[[Animals|Animalia]]
|-
!style="min-width:6em; |Subkingdom:
|style="min-width:6em; |Bilateria
|-
!style="min-width:6em; |Infrakingdom:
|style="min-width:6em; |Protostomia
|-
!style="min-width:6em; |Superphylum:
|style="min-width:6em; |Ecdysozoa
|-
!style="min-width:6em; |Phylum:
|style="min-width:6em; |Arthropoda
|-
!style="min-width:6em; |Subphylum:
|style="min-width:6em; |Crustacea
|-
|colspan="2" |Source: Integrated Taxonomic Information System
|}

Crustaceans belong to the phylum Arthropoda, but are more commonly referred to using their subphylum, Crustacea. Crustaceans are the sole members of Crustacea but represent an immensely diverse group that encompasses an approximate 50,000 known species which span an equally broad range of environments. Crustacea has a metropolitan distribution (worldwide) with members most commonly found in all aquatic environments like that of marine, brackish, and freshwater systems. Though members of Crustacea can be found roaming terrestrially, only two crustaceans are known to be fully terrestrial, living their entire lives on land. Land Crustacea are [[Nutrient Cycling|nutrient cycling]] [[detritivores]] while the rest, and vast majority of crustaceans, are scavengers, benthic bottom feeders, and general or obligate parasites.

== Taxonomy ==
The Crustacea subphyla is a paraphyletic group which consists of all taxa that originally comprised all “traditional crustaceans”, and now classifies [[organisms]] within three superclasses. These three superclasses are the Multicrustacea, Oligostraca, and Allotriocarida, which together form the Pancrustacea monophyletic group with the addition of the [[insects]] of Hexapoda. Mulitcrustacea represents the largest proportion of crustaceans containting approximately 80% of all recorded crustaceans, like that of crabs, barnacles, and woodlice. Crustacea itself can is commonly subdivided into 10 subclasses, commonly referred to as “direct children” classes.

=== Children Classes ===
*Class Cephalocarida:
:-Horseshoe shrimps which are among the oldest, most primitive members of Crustacea; all known species are bottom-dwelling, benthic organisms.
*Class Branchiopoda:
:-Includes tadpole, fairy, and brine shrimps, all of whom are small, freshwater organisms which feed upon plankton and detritus. Make up an important base of the food chain.
*Class Ostracoda:
:-Ostracods are microscopic, aquatic organisms which are among the most basal forms of Crustacea. They are commonly used for dating within the fossil record due to their abundancy and widespread distribution.
*Class Copepoda:
:-Very small aquatic organisms which live in both fresh and saltwater. Copepods are commonly parasitic, or have parasitic phases across their life cycle.
*Class Mystacocarida:
:-Microscopic organisms which live in between the grains of [[sand]] of intertidal beaches. Form part of the meiobenthos, the trophic link between bacteria and larger fauna.
*Class Remipedia:
:-Blind organisms commonly found in coastal aquifers; also the only known venomous crustaceans in the world.
*Class Tantulocarida:
:-Ectoparasites which are highly specialized obligate feeders commonly found on [[isopods]].
*Class Branchiura:
:-Parasitic residing on or in most fish, back and forth debate placing the group within Crustacea and Annelida.
*Class Cirripedia:
:-Barnacles which reside exclusively in shallow tidal waters. Are sessile (nonmobile) suspension feeders or highly specialized obligate parasites.
*Class Malacostraca:
:-Approximately 70% of all crustaceans, includes lobsters, crayfish, crabs, shrimps, isopods, and most other well-known aquatic crustaceans.

== Crustacean Characteristics ==

=== Generalizations ===
The wide distribution, and wider evolutionary track of crustaceans has created an extensively complex group of organisms which create numerous exceptions to any general rules and basic features used to generalize organisms. However, with that said, some generalizations surrounding the physical development and appearance of crustaceans can still be made and used to assist in taxonomic placement.

Firstly, Crustacea differ from their parent phylum Arthropoda due to the development of an additional pair of appendages known as antennules. Antennules develop on the first segment of the head, just ahead of the antennae which form on the second segment of the head. Crustacea themselves can then be delineated according to morphological composition based upon the number and makeup of body segments.

=== Body development ===
Each body segment will develop from a set of precursor cells called somite(s). Each somite can develop individually to allow for greater mobility or be fused together with any number of other somites to produce more complex body segments like that of the anterior (head) of the crustacean, which is a created by the fusion of four somites and an unsegmented region called the acron. The posterior, or backend of the crustacean, develops via a similar mechanism by which somites fuse with another unsegmented region called the telson, to form a furca, which then itself undergoes further development into either a shorter, compact tail or the rare elongation event to create a tail equal to, or greater in length than the segmented body.

This variable somite fusion leads to the immense morphological disparity in body form and appendage development seen across the subphylum. While diverse, there is commonly consistency seen across any one class: for instance, Malacostraca, which contains about 70% of crustaceans, follows a body plan of head, trunk, thorax, and abdomen. Though different in appearance and or use, the carapace, a hard protective structure behind the head, is also a widespread morphological feature. Appendage appearance and use tends to allow for specialization, often creating or heightening functions associated with feeding, movement, reproduction, or just about any other task. Appendage and body form disparity is highlighted when comparing the 12 ft leg span of the Japanese Spider Crab to that of an approximately 0.009-inch parasitic copepod, which ironically can be found in most Japanese Spider Crabs.

=== Life Histories ===
The development of crustaceans follows the now common theme in which [[diversity]] creates an increasingly variable means of development and subsequent natural history.

==== Reproduction ====
In terms of reproductions, Crustacea can display both sexual and asexual reproduction, a few species are hermaphroditic, others can change sex across their lifespan, and when unable to find a mate, parthenogenesis is commonly used.

==== Juvenile Development ====
[[File: Crust 3 Life cycle.jpg|left|450px|thumb|Visual representation of the crustacean life cycle]]
In all known forms, the crustacean life cycle begins with the egg, in which the immature crustacean will either emerge as a scaled down version of an adult or as a larva which will develop further. Crustaceans developmental path is thus classified as being either anamorphic (larvae-based) or epimorphic (smaller adult hatchling); the dichotomous nature of hatchling development is highly conserved across taxa and is often used for classification. Additionally, like other organisms classified under Arthropoda, crustaceans must molt and shed their exoskeletons to further grow in body size, and in the case of larval organisms, to add appendages.

===== Anamorphic Development =====
Anamorphic development involves a series of larval stages which utilize the process of molting to further morphological development of segments and appendages which aren’t initially present. Anamorphic development is typically comprised of three larval stages referred to as the nauplius, zoea, and megalopa / mysis stages.

*‘’’Nauplius:’’’
::The nauplius (plural nauplii) stage details a larva which has recently emerged from its egg and is categorized as a “floating” head with a single eye and typically three pairs of appendages which it uses for mobility. Some anamorphic crustaceans will “skip” this larval stage and instead emerge from the egg at further into development.
*’’’Zoea:’’’
::During the zoea stage, the larva is acknowledged by the presence of both a cephalon (head) and thorax (a body segment). By the end of this stage, it will add abdominal segments and may also have a pair of compound eyes. Zoea swim using biramous (branched), thoracic appendages.
*’’’Megalopa or Mysis:’’’
::By the megalopa (typically for crabs / lobsters) or mysis (usually more “basic” crustaceans) stage, the crustacean will have added the segments and appropriate appendages of all three body regions (cephalon [head], thorax, and abdomen), as well as, for aquatic species, the development of at least one pair of swimmerets (appendages used for forward motion). At this point, the individual will look like a proportionally accurate, but smaller version of an adult that is sexually immature.

===== Epimorphic Development =====
Epimorphic crustaceans instead develop within their eggs and emerge at the same respective stage of development as anamorphic organisms do following the completion of their larval stages. Therefore, epimorphic development is defined by the absence of any larval stages, instead opting to follow a similar series of development stages within the safety of their egg to then emerge as a fully segmented, appendage baring, downsized version of its adult counterpart.

== Soil Crustaceans ==
Crustacea utilize a wide range of habitat in conjunction with their wide range of morphological forms. Environmental conditions range anywhere from the pressure of the deep ocean, freshwater systems, high salt concentration brine lakes, and even the high arctic where a dormant overwintering stage follows reproduction during the short summers. Many crustaceans have adapted to terrestrial life in order to hunt, reproduce, or even to avoid predation. Notably, the only known fully terrestrial members of crustacea are the sow bug and pill bug of the order Isopoda and class Malacostraca.
[[File: Crust 2 Iso v Sow.jpeg|right|thumb|500px|A: A diagram depicting the different physical characteristics of terrestrial isopods]]

Sow bugs and pill bugs are commonly grouped together and referred to as woodlice (singular woodlouse). These fully terrestrial isopods reside in moist [[soil]] and are commonly found under log, stones, and any other ground debris. Woodlice are primarily detritivores which feed upon dead or decaying plant matter and are critical to nutrient recycling and the subsequent soil health of a habitat. Though very similar at first glance, the two isopods can be distinguished due the sow bug’s lighter colorway and more articulated (jointed) appendages. Additionally, the pillbug, also referred to as a roly poly, has the ability roll into a tight protective ball, an ability the sow bug lacks.

== References ==
#Arndt, C. E., and K. M. Swadling. 2006. Crustacea in Arctic and Antarctic Sea Ice: Distribution, Diet and Life History Strategies. Pages 197–315 Advances in Marine Biology. Academic Press.
#Copilaş-Ciocianu, D., and B. V. Boroş. 2016. Contrasting life history strategies in a phylogenetically diverse community of freshwater amphipods (Crustacea: Malacostraca). Zoology 119:21–29.
#Crustacean | Definition, Characteristics, Evolution, & Facts | Britannica. (n.d.). . https://www.britannica.com/animal/crustacean.
#El-Bawab, F. 2020. Chapter 10 - Phylum Crustacea, Pennant (1777). Pages 475–711 in F. El-Bawab, editor. Invertebrate Embryology and Reproduction.Academic Press.
#ITIS - Report: Crustacea. (n.d.). . https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=83677#null.
#Jiravanichpaisal, P., N. Puanglarp, S. Petkon, S. Donnuea, I. Söderhäll, and K. Söderhäll. 2007. Expression of immune-related genes in larval stages of the giant tiger shrimp, Penaeus monodon. Fish & Shellfish Immunology 23:815–824.
#Paoletti, M. G., and M. Hassall. 1999. Woodlice (Isopoda: Oniscidea): their potential for assessing sustainability and use as bioindicators.Agriculture, Ecosystems & Environment 74:157–165.
#Subramoniam, T. 2017. Chapter 3 - Sexual Systems. Pages 57–103 in T. Subramoniam, editor. Sexual Biology and Reproduction in Crustaceans. AcademicPress.
#The Fascinating Differences Between Isopods And Pillbugs | Adopt And Shop. 2023, January 23. .
#What Do Crustaceans Have to Do With Bugs? (n.d.). . https://www.thoughtco.com/subphylum-crustacea-crustaceans-1968439.
#Wood, C. T., R. Kostanjšek, P. B. Araujo, and J. Štrus. 2017. Morphology, microhabitat selection and life-history traits of two sympatric woodlice (Crustacea: Isopoda: Oniscidea): A comparative analysis. Zoologischer Anzeiger 268:1–10.
#WoRMS - World Register of Marine Species - Crustacea. (n.d.). . https://www.marinespecies.org/aphia.php?p=taxdetails&id=1066.

Crustacean

2023-04-01T21:09:07Z

{| class="wikitable" style="text-align:center; float:right; margin-left: 10px;
|+ !colspan="2" style="min-width:12em; text-align: center; background-color: rgb(235,235,210)|'''Taxonomic Classification'''
|-
|colspan="2" |[[File:Crustacea 1 - Range of crustacean appearance.jpeg|400px|caption]]
|-
!style="min-width:6em; |Kingdom:
|style="min-width:6em; |[[Animals|Animalia]]
|-
!style="min-width:6em; |Subkingdom:
|style="min-width:6em; |Bilateria
|-
!style="min-width:6em; |Infrakingdom:
|style="min-width:6em; |Protostomia
|-
!style="min-width:6em; |Superphylum:
|style="min-width:6em; |Ecdysozoa
|-
!style="min-width:6em; |Phylum:
|style="min-width:6em; |Arthropoda
|-
!style="min-width:6em; |Subphyla:
|style="min-width:6em; |Crustacea
|-
|colspan="2" |Source: Integrated Taxonomic Information System
|}

Crustaceans belong to the phylum Arthropoda, but are more commonly referred to using their subphylum, Crustacea. Crustaceans are the sole members of Crustacea but represent an immensely diverse group that encompasses an approximate 50,000 known species which span an equally broad range of environments. Crustacea has a metropolitan distribution (worldwide) with members most commonly found in all aquatic environments like that of marine, brackish, and freshwater systems. Though members of Crustacea can be found roaming terrestrially, only two crustaceans are known to be fully terrestrial, living their entire lives on land. Land Crustacea are nutrient cycling [[detritivores]] while the rest, and vast majority of crustaceans, are scavengers, benthic bottom feeders, and general or obligate parasites.

== Taxonomy ==
The Crustacea subphyla is a paraphyletic group which consists of all taxa that originally comprised all “traditional crustaceans”, and now classifies [[organisms]] within three superclasses. These three superclasses are the Multicrustacea, Oligostraca, and Allotriocarida, which together form the Pancrustacea monophyletic group with the addition of the [[insects]] of Hexapoda. Mulitcrustacea represents the largest proportion of crustaceans containting approximately 80% of all recorded crustaceans, like that of crabs, barnacles, and woodlice. Crustacea itself can is commonly subdivided into 10 subclasses, commonly referred to as “direct children” classes.

=== Children Classes ===
*Class Cephalocarida:
:-Horseshoe shrimps which are among the oldest, most primitive members of Crustacea; all known species are bottom-dwelling, benthic organisms.
*Class Branchiopoda:
:-Includes tadpole, fairy, and brine shrimps, all of whom are small, freshwater organisms which feed upon plankton and detritus. Make up an important base of the food chain.
*Class Ostracoda:
:-Ostracods are microscopic, aquatic organisms which are among the most basal forms of Crustacea. They are commonly used for dating within the fossil record due to their abundancy and widespread distribution.
*Class Copepoda:
:-Very small aquatic organisms which live in both fresh and saltwater. Copepods are commonly parasitic, or have parasitic phases across their life cycle.
*Class Mystacocarida:
:-Microscopic organisms which live in between the grains of [[sand]] of intertidal beaches. Form part of the meiobenthos, the trophic link between bacteria and larger fauna.
*Class Remipedia:
:-Blind organisms commonly found in coastal aquifers; also the only known venomous crustaceans in the world.
*Class Tantulocarida:
:-Ectoparasites which are highly specialized obligate feeders commonly found on [[isopods]].
*Class Branchiura:
:-Parasitic residing on or in most fish, back and forth debate placing the group within Crustacea and Annelida.
*Class Cirripedia:
:-Barnacles which reside exclusively in shallow tidal waters. Are sessile (nonmobile) suspension feeders or highly specialized obligate parasites.
*Class Malacostraca:
:-Approximately 70% of all crustaceans, includes lobsters, crayfish, crabs, shrimps, isopods, and most other well-known aquatic crustaceans.

== Crustacean Characteristics ==

=== Generalizations ===
The wide distribution, and wider evolutionary track of crustaceans has created an extensively complex group of organisms which create numerous exceptions to any general rules and basic features used to generalize organisms. However, with that said, some generalizations surrounding the physical development and appearance of crustaceans can still be made and used to assist in taxonomic placement.

Firstly, Crustacea differ from their parent phylum Arthropoda due to the development of an additional pair of appendages known as antennules. Antennules develop on the first segment of the head, just ahead of the antennae which form on the second segment of the head. Crustacea themselves can then be delineated according to morphological composition based upon the number and makeup of body segments.

=== Body development ===
Each body segment will develop from a set of precursor cells called somite(s). Each somite can develop individually to allow for greater mobility or be fused together with any number of other somites to produce more complex body segments like that of the anterior (head) of the crustacean, which is a created by the fusion of four somites and an unsegmented region called the acron. The posterior, or backend of the crustacean, develops via a similar mechanism by which somites fuse with another unsegmented region called the telson, to form a furca, which then itself undergoes further development into either a shorter, compact tail or the rare elongation event to create a tail equal to, or greater in length than the segmented body.

This variable somite fusion leads to the immense morphological disparity in body form and appendage development seen across the subphylum. While diverse, there is commonly consistency seen across any one class: for instance, Malacostraca, which contains about 70% of crustaceans, follows a body plan of head, trunk, thorax, and abdomen. Though different in appearance and or use, the carapace, a hard protective structure behind the head, is also a widespread morphological feature. Appendage appearance and use tends to allow for specialization, often creating or heightening functions associated with feeding, movement, reproduction, or just about any other task. Appendage and body form disparity is highlighted when comparing the 12 ft leg span of the Japanese Spider Crab to that of an approximately 0.009-inch parasitic copepod, which ironically can be found in most Japanese Spider Crabs.

=== Life Histories ===
The development of crustaceans follows the now common theme in which [[diversity]] creates an increasingly variable means of development and subsequent natural history.

==== Reproduction ====
In terms of reproductions, Crustacea can display both sexual and asexual reproduction, a few species are hermaphroditic, others can change sex across their lifespan, and when unable to find a mate, parthenogenesis is commonly used.

==== Juvenile Development ====
[[File: Crust 3 Life cycle.jpg|left|450px|thumb|Visual representation of the crustacean life cycle]]
In all known forms, the crustacean life cycle begins with the egg, in which the immature crustacean will either emerge as a scaled down version of an adult or as a larva which will develop further. Crustaceans developmental path is thus classified as being either anamorphic (larvae-based) or epimorphic (smaller adult hatchling); the dichotomous nature of hatchling development is highly conserved across taxa and is often used for classification. Additionally, like other organisms classified under Arthropoda, crustaceans must molt and shed their exoskeletons to further grow in body size, and in the case of larval organisms, to add appendages.

===== Anamorphic Development =====
Anamorphic development involves a series of larval stages which utilize the process of molting to further morphological development of segments and appendages which aren’t initially present. Anamorphic development is typically comprised of three larval stages referred to as the nauplius, zoea, and megalopa / mysis stages.

*‘’’Nauplius:’’’
::The nauplius (plural nauplii) stage details a larva which has recently emerged from its egg and is categorized as a “floating” head with a single eye and typically three pairs of appendages which it uses for mobility. Some anamorphic crustaceans will “skip” this larval stage and instead emerge from the egg at further into development.
*’’’Zoea:’’’
::During the zoea stage, the larva is acknowledged by the presence of both a cephalon (head) and thorax (a body segment). By the end of this stage, it will add abdominal segments and may also have a pair of compound eyes. Zoea swim using biramous (branched), thoracic appendages.
*’’’Megalopa or Mysis:’’’
::By the megalopa (typically for crabs / lobsters) or mysis (usually more “basic” crustaceans) stage, the crustacean will have added the segments and appropriate appendages of all three body regions (cephalon [head], thorax, and abdomen), as well as, for aquatic species, the development of at least one pair of swimmerets (appendages used for forward motion). At this point, the individual will look like a proportionally accurate, but smaller version of an adult that is sexually immature.

===== Epimorphic Development =====
Epimorphic crustaceans instead develop within their eggs and emerge at the same respective stage of development as anamorphic organisms do following the completion of their larval stages. Therefore, epimorphic development is defined by the absence of any larval stages, instead opting to follow a similar series of development stages within the safety of their egg to then emerge as a fully segmented, appendage baring, downsized version of its adult counterpart.

== Soil Crustaceans ==
Crustacea utilize a wide range of habitat in conjunction with their wide range of morphological forms. Environmental conditions range anywhere from the pressure of the deep ocean, freshwater systems, high salt concentration brine lakes, and even the high arctic where a dormant overwintering stage follows reproduction during the short summers. Many crustaceans have adapted to terrestrial life in order to hunt, reproduce, or even to avoid predation. Notably, the only known fully terrestrial members of crustacea are the sow bug and pill bug of the order Isopoda and class Malacostraca.
[[File: Crust 2 Iso v Sow.jpeg|right|thumb|500px|A: A diagram depicting the different physical characteristics of terrestrial isopods]]

Sow bugs and pill bugs are commonly grouped together and referred to as woodlice (singular woodlouse). These fully terrestrial isopods reside in moist [[soil]] and are commonly found under log, stones, and any other ground debris. Woodlice are primarily detritivores which feed upon dead or decaying plant matter and are critical to nutrient recycling and the subsequent soil health of a habitat. Though very similar at first glance, the two isopods can be distinguished due the sow bug’s lighter colorway and more articulated (jointed) appendages. Additionally, the pillbug, also referred to as a roly poly, has the ability roll into a tight protective ball, an ability the sow bug lacks.

== References ==
#Arndt, C. E., and K. M. Swadling. 2006. Crustacea in Arctic and Antarctic Sea Ice: Distribution, Diet and Life History Strategies. Pages 197–315 Advances in Marine Biology. Academic Press.
#Copilaş-Ciocianu, D., and B. V. Boroş. 2016. Contrasting life history strategies in a phylogenetically diverse community of freshwater amphipods (Crustacea: Malacostraca). Zoology 119:21–29.
#Crustacean | Definition, Characteristics, Evolution, & Facts | Britannica. (n.d.). . https://www.britannica.com/animal/crustacean.
#El-Bawab, F. 2020. Chapter 10 - Phylum Crustacea, Pennant (1777). Pages 475–711 in F. El-Bawab, editor. Invertebrate Embryology and Reproduction.Academic Press.
#ITIS - Report: Crustacea. (n.d.). . https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=83677#null.
#Jiravanichpaisal, P., N. Puanglarp, S. Petkon, S. Donnuea, I. Söderhäll, and K. Söderhäll. 2007. Expression of immune-related genes in larval stages of the giant tiger shrimp, Penaeus monodon. Fish & Shellfish Immunology 23:815–824.
#Paoletti, M. G., and M. Hassall. 1999. Woodlice (Isopoda: Oniscidea): their potential for assessing sustainability and use as bioindicators.Agriculture, Ecosystems & Environment 74:157–165.
#Subramoniam, T. 2017. Chapter 3 - Sexual Systems. Pages 57–103 in T. Subramoniam, editor. Sexual Biology and Reproduction in Crustaceans. AcademicPress.
#The Fascinating Differences Between Isopods And Pillbugs | Adopt And Shop. 2023, January 23. .
#What Do Crustaceans Have to Do With Bugs? (n.d.). . https://www.thoughtco.com/subphylum-crustacea-crustaceans-1968439.
#Wood, C. T., R. Kostanjšek, P. B. Araujo, and J. Štrus. 2017. Morphology, microhabitat selection and life-history traits of two sympatric woodlice (Crustacea: Isopoda: Oniscidea): A comparative analysis. Zoologischer Anzeiger 268:1–10.
#WoRMS - World Register of Marine Species - Crustacea. (n.d.). . https://www.marinespecies.org/aphia.php?p=taxdetails&id=1066.

File:Crust 3 Life cycle.jpg

2023-04-01T20:32:39Z

Jmcruz3:

File:Crust 2 Iso v Sow.jpeg

2023-04-01T20:32:25Z

Jmcruz3:

File:Crustacea 1 - Range of crustacean appearance.jpeg

2023-04-01T16:10:46Z

Jmcruz3:

Chytridiomycota

2023-03-10T19:59:44Z

Jmcruz3:

'''Chytridiomycota''' commonly referred to as Chytrid(s), is a phylum of zoosporic [[organisms]] within the fungi kingdom. Thought to be the oldest and most basal group of fungi,[6] Chytrids can be identified in substrate from the late Precambrian period over 500 MYA.[1] Though among the most ancient known fungi, Chytrids were first recorded in 1886 as vesicular structures which use prominent root-like appendages to anchor onto their desired substrate.[11] There is considerable variation in the morphological and ecological make-up of the phylum; this is exemplified by the approximately 1000 combined described species which inhabit both marine and, to a lesser extent, terrestrial substrates.[7]

[[File:Spizellomyces palustris monocentric eucarpic.jpg |frame|50ppx|right|Spizellomyces palustris, a monocentric, eucarpic chytrid. From Chen, et al. (2000).]]

==Taxonomy==
Chytridiomycota, one of the five total phyla of true fungi, make up the entirety of their own phylum.[1] Though Chytrids are the simplest of the true fungi, the phylum resolves into five distinct orders which include the Blastocladiles, Chytridialis, Monoblepharidales, Neocallimastigales, and Spizellomy
cetales.[6]

==Characteristics==
Chytridiomycota reside in a wide range of aquatic habitats, however, a few species are considered to be terrestrial.[1] Like all fungi, Chytridiomycota contain cell walls made of chitin, however, the hyphochytrid subgroup represents the common exception as their cell walls utilize cellulose.[1][6] Chytrids can further be delineated by their cellularity, with most being unicellular while a select few can be considered multicellular due their production of hyphae.[1] Though technically hyphae, the chytrid’s structures do not contain the typical cells divisions created by internal walls called septa (singular septum), which allow for the transfer of organelles across membranes. The most prominent morphological trait of adult Chytridiomycota is the sac-like structure of the sporangia; in which internal divisions of the protoplasm result in zoospore production. Fungi within the phylum display an additional defining characteristic unseen in all other known fungi of any life stage, a flagellum which is used by their zoospores.[1][3][7]

==Life cycle==
Chytridiomycota reproduction is generally asexual, though notable exceptions occur between species and their relative ecological niches. Asexual reproduction takes the form of mitotic divisions and the subsequent production of their motile, water dependent zoospore. Sexual reproduction utilizes pheromone signaling to attract variably sized and colored gametes for conjugation. Further chytrid development relies upon the occupation of their desired environmental niche, upon which the individual will encyst and begin creating its cell wall. Development after the process of encysting is dependent upon the individual species, however, a few generalizations can be made. Growth will stimulate the formation of a thallus (the nondifferentiated cell and its wall) and either the hyphae-like anchoring appendage called a rhizoid or permeable true hyphae.[10] Parasitic Chytridiomycota will produce and contain microsporidia, despite the loss of their zoospore stage. [8][10]

==[[Ecology]]==
Chytridiomycota are either [[saprobic]] or parasitic depending on their substrate, aquatic or terrestrial respectively .[1] The parasitic relationships formed by Chytrids is highlighted by Batrachochytrium dendrobatidis, also known as Bd, which is the causative agent of chytridiomycosis in amphibians. Chytridiomycosis results in malformed skin which inhibits respiration and increases mortality which has led to a global decline in amphibian populations. [2][3] Chytrids are also commonly parasitic to the roots of plants. They are important vectors of viruses in plants and algae, as they have been known to cause serious damage which can expose the host to opportunistic infections.[2][7] Chytrids have been found to play an important role in the gut of many mammals, forming a proportionally rare mutualistic relationship.[2][11]

===Role in Soil===
Aquatic Chytrid species are saprobic, serving as decomposers in their environments. Terrestrial Chytrids are primarily thought to be obligate parasites in hosts of vascular plants, or more rarely, algae.[7] Due to their aquatic nature of the majority of Chytrids, the phylum has traditionally been considered to play little role in [[soil]] processes. There is increasing evidence that in periglacial soils chytrid fungi can make up 70% of fungal [[diversity]] and 30% of eukaryotic diversity; though this has shown to only be true in unvegetated areas at high altitudes. Chytrids in these high elevation areas make up the majority of decomposers for the photosynthetic microbial food chain, further relying upon snowmelt for dispersal and proliferation.[5]

===Chytridiomycosis===
Batrachochytrium dendrobatidis (Bd) was previously the only known instance of parasitic chytrid fungi within vertebrates.[7]. Batrachochytrium dendrobatidis is known to infect over 350 species of amphibians, though frogs appear to be among the most severely impacted. Chytridiomycosis occurs when Zoospores infect the keratin layer of the skin, resulting in excessive skin shedding. The earliest symptoms are anorexia and lethargy, though prolonged Infection may eventually lead to secondary infections and result in death of the host.[9]

==References==

[1] 24.3A: Chytridiomycota: The Chytrids. 2018, July 15. . https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Book%3A_General_Biology_(Boundless)/24%3A_Fungi/24.3%3A_Classifications_of_Fungi/24.3A%3A_Chytridiomycota%3A_The_Chytrids.

[2] Chytridiomycota. (n.d.). . http://website.nbm-mnb.ca/mycologywebpages/NaturalHistoryOfFungi/Chytridiomycota.html.

[3] Chytridiomycota | phylum of fungi. (n.d.). . https://www.britannica.com/science/Chytridiomycota.

[4] Fisher, M. C., and T. W. J. Garner. 2020. Chytrid fungi and global amphibian declines. Nature Reviews Microbiology 18:332–343.

[5] Freeman, K. R., A. P. Martin, D. Karki, R. C. Lynch, M. S. Mitter, A. F. Meyer, J. E. Longcore, D. R. Simmons, and S. K. Schmidt. 2009. Evidence that chytrids dominate fungal communities in high-elevation soils. Proceedings of the National Academy of Sciences 106:18315–18320.

[6] Ibelings, B. W., A. D. Bruin, M. Kagami, M. Rijkeboer, M. Brehm, and E. V. Donk. 2004. Host Parasite Interactions Between Freshwater Phytoplankton and Chytrid Fungi (chytridiomycota)1. Journal of Phycology 40:437–453..

[7] James, T. Y., P. M. Letcher, J. E. Longcore, S. E. Mozley-Standridge, D. Porter, M. J. Powell, G. W. Griffith, and R. Vilgalys. 2006b. A Molecular Phylogeny of the Flagellated Fungi (Chytridiomycota) and Description of a New Phylum (Blastocladiomycota). Mycologia 98:860–871.

[8] James, T. Y., A. Pelin, L. Bonen, S. Ahrendt, D. Sain, N. Corradi, and J. E. Stajich. 2013. Shared Signatures of Parasitism and Phylogenomics Unite Cryptomycota and Microsporidia. Current Biology 23:1548–1553.

[9] jlp342. 2018, March 21. Chytridiomycosis. Text. https://cwhl.vet.cornell.edu/disease/chytridiomycosis.

[10] Medina, E. M., and N. E. Buchler. 2020. Chytrid fungi. Current Biology 30:R516–R520.

[11] Taylor, Thomas N., et al. 2014. Fossil Fungi, Elsevier Science & Technology. ProQuest Ebook Central, https://ebookcentral-proquest-com.gate.lib.buffalo.edu/lib/buffalo/detail.action?docID=1774309.