Rhodochorton
| Rhodochorton | |
|---|---|
 | |
| Rhodochorton subsimplex | |
| Scientific classification | |
| (unranked): | Archaeplastida |
| Division: | Rhodophyta |
| Class: | Florideophyceae |
| Order: | Acrochaetiales |
| Family: | Acrochaetiaceae |
| Genus: | Rhodochorton Nägeli[1] |
| Species | |
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Species include:
| |
Rhodochorton is a genus of filamentous red alga adapted to low light levels. It may form tufts or a thin purple "turf" up to 5 millimetres high. The filaments branch infrequently, usually at the tips.[2]
Morphology
In most species of Rhodochorton, the spore does not persist in the mature plant; instead, a basal web of filaments acts as a holdfast. Indeed, all Rhodochorton species have distinct basal threads, usually forming a disc, and upright threads, which are typically thinner.[2] Lateral branches usually occur at or near the top of the patent cell, and branching is concentrated towards the tips of threads.[2]
Ecology
The organism may encrust bare rock surfaces, or be epiphytic upon frondose algae - particularly Laminaria hyperborea.[3] It typically grows in the shadow of these larger algae, in the intertidal zone,[4] and its adaption to low light levels means it is also common in caves.[2] It reproduces in winter using tetrasporangia and don't bear any monosporangia.[5] Rhodochorton is typically marine, but R. investiens dwells in fresh water.[6] Sexual reproduction has never been observed.[7]
It suffers grazing pressure from gastropods and amphipods, but amazingly fragments of the algae are able to pass through the grazers' digestive tracts alive - grazing may actually form a mode of dispersal for the organism.[4]
Life history
Rhodochorton investiens displays a relatively simple life cycle for a red alga.[8]
In the Carposporophyte: a spermatium merges with a trichogyne (a long hair on the female sexual organ), which then divides to form carposporangia - which produce carpospores.
Carpospores germinate into gametophytes, which produce sporophytes. Both of these are very similar; they produce monospores from monosporangia "just below a cross wall in a filament"[8] and their spores are "liberated through apex of sporangial cell."[8]
The spores of a sporophyte produce either tetrasporophytes. Monospores produced by this phase germinate immediately, with no resting phase, to form an identical copy of parent. Tetrasporophytes may also produce a carpospore, which germinates to form another tetrasporophyte.[8]
The gametophyte may replicate using monospores, but produces sperm in spermatangia, and "eggs"(?) in carpogonium.[8]
See also
The following species closely resemble Rhodochorton: Rhodothamniella
References
- ↑ Dixon, 1982:64
- 1 2 3 4 Fritsch, F. E. (1945), The structure and reproduction of the algae, Cambridge: Cambridge Univ. Press, ISBN 0-521-05042-1, OCLC 223742770
- ↑ http://www.horta.uac.pt/Species/Algae/Rhodochorton_purpureum/Rhodochorton_purpureum.htm
- 1 2 Breeman, A. M.; Hoeksema, B. W. (1987), "Vegetative propagation of the red alga Rhodochorton purpureum by means of fragments that escape digestion by herbivores" (PDF), Mar. Ecol. Prog. Ser., 35: 197–201, doi:10.3354/meps035197
- ↑ West, John A. (1969), "The Life Histories Of Rhodochorton Purpureum And R. Tenue In Culture", Journal of Phycology, 5: 12, doi:10.1111/j.1529-8817.1969.tb02569.x.
- ↑ Swale, E. M. F.; Belcher, J. H. (April 1, 1963), "Morphological Observations on Wild and Cultured Material of Rhodochorton investiens (Lenormand) nov. comb. (Balbiania investiens (Lenorm.) Sirodot)", Annals of Botany, Annals Botany Co, 27 (2): 282–290
- ↑ West, John A. (1970), "A Monoecious Isolate Of Rhodochorton purpureum", Journal of Phycology, 6 (4): 368, doi:10.1111/j.0022-3646.1970.00368.x.
- 1 2 3 4 5 Lee, R.E. (2008), Phycology, 4th edition, Cambridge University Press, ISBN 978-0-521-63883-8