Rhodochorton
Template:Short description Template:Automatic taxobox
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.[1]
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.[1] Lateral branches usually occur at or near the top of the patent cell, and branching is concentrated towards the tips of threads.[1]
Ecology
The organism may encrust bare rock surfaces, or be epiphytic upon frondose algae - particularly Laminaria hyperborea.[2] It typically grows in the shadow of these larger algae, in the intertidal zone,[3] and its adaption to low light levels means it is also common in caves.[1] It reproduces in winter using tetrasporangia and don't bear any monosporangia.[4] Rhodochorton is typically marine, but R. investiens dwells in fresh water.[5] Sexual reproduction has never been observed.[6]
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.[3]
Life history
Rhodochorton investiens displays a relatively simple life cycle for a red alga.[7]
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"[7] and their spores are "liberated through apex of sporangial cell."[7]
The spores of a sporophyte produce 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.Script error: No such module "Unsubst".[7]
The gametophyte may replicate using monospores, but produces sperm in spermatangia, and "eggs"(?) in carpogonium.[7]
See also
- Rhodothamniella, a genus that closely resembles Rhodochorton
References
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