Dictionary of Meaning
<<Back
Please select a letter:
A |
B |
C |
D |
E |
F |
G |
H |
I |
J |
K |
L |
M |
N |
O |
P |
Q |
R |
S |
T |
U |
V |
W |
X |
Y |
Z |
0-9
Click here for Shopping
Myxozoa
*** Shopping-Tip: Myxozoa
{{Taxobox
| color = pink
| name = Myxozoa
| regnum =
Animalia
| phylum = '''Myxozoa'''
| phylum_authority = Grassé, 1970
| subdivision_ranks =
Class (biology) Classes
| subdivision =
Malacosporea
Myxosporea
}}
The '''Myxozoa''' are a group of
microscopic,
parasite parasitic animals. Originally taxonomists classed them as
protozoa, and included them with other non-motile forms in the group
Sporozoa. However, as their distinct nature became clear they gained their own phylum. Evolutionary theorists now generally consider them to have developed from multicellular
animals, and classify them accordingly.
The Greek roots of the name ''myxozoa'' express the ideas of "slime" or "mucus" (''myx-'') and "animal" (''zo-'').
Many Myxozoa have a two-host lifecycle, involving a
fish and an
annelid worm or
bryozoan. Infection occurs by valved spores. These contain one or two
sporoblast cells, and one or more polar capsules, containing filaments that anchor the spore to its host. The sporoblasts are then released as a motile form called an amoebula, which penetrates the host tissues and develops into one or more multinucleate
plasmodium plasmodia. Certain nuclei later pair up, one engulfing another, to form new spores.
In structure and appearance the polar capsules closely resemble the stinging cells of
Cnidaria. On account of this, biologists have generally regarded the Myxozoa as extremely reduced cnidarians, and in particular as close relatives of ''
Polypodium'', with some genetic support. More recent studies of
Homeobox Hox genes, however, point to an origin among the
Bilateria. Strong support for this comes from the discovery that ''
Buddenbrockia'', a worm-like parasite of
bryozoans up to 2 mm in length, belongs among the Myxozoa{{ref|Monteiro}}. Genetically difficult to distinguish from the other forms, it has Myxozoan-like spore capsules, but it retains a bilateral body form with longitudinal muscles. This serves as a
missing link between the Myxozoa and their multicellular ancestors.
Taxonomists now recognize the outdated subgroup
Actinosporea as a
biological life cycle life-cycle phase of
Myxosporea {{ref|Kent}}.
Species
Some species of myxozoa include:
*Class
Malacosporea
**''
Buddenbrockia plumatellae''
**''
Tetracapsuloides bryosalmonae'' - an important
salmon parasite
*Class
Myxosporea
**''
Myxobolus cerebralis'' - an important parasite of salmon and
trout
Notes
*{{Note|Kent}}Kent, M. L., Margolis, L. & Corliss, J.O. (1994). "The demise of a class of protists: taxonomic and nomenclatural revisions proposed for the protist phylum Myxozoa Grasse, 1970." ''Canadian Journal of Zoology'' 72(5):932-937.
*{{note|Monteiro}}Monteiro, A. S., Okamura, B., and P. W. H. Holland. "Orphan Worm Finds a Home: Buddenbrockia is a Myxozoan." ''Molecular Biology and Evolution'' 19:968-971 (2002)[http://mbe.oupjournals.org/cgi/content/full/19/6/968]
Category:AnimalsCategory:ParasitesCategory:Myxozoa *
cs:Výtrusenky
da:Myxozoa
de:Myxozoa
fr:Myxozoa
nl:Myxozoa
pt:Myxozoa
{{sisterlinkswp|Category:Myxozoa}}
Category:Animals
Category:Parasites
*** Shopping-Tip: Myxozoa
