''Ulothrix flacca'' is a species of
green algae
The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ...
in the family
Ulotrichaceae. It is a marine or brackish species, typically found in the
intertidal zone
The intertidal zone or foreshore is the area above water level at low tide and underwater at high tide; in other words, it is the part of the littoral zone within the tidal range. This area can include several types of habitats with various ...
.
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Description
''Ulothrix flacca'' grows as small tufts of green unbranched filaments growing to no more than 10 cm long, forming woolly masses attached to rocks. It consists of soft, long filaments which are uniseriate (very rarely a cell may undergo longitudinal division and become biseriate). Basal cells are elongated, or in mature filaments, differentiated into a complex rhizoidal branching system.[Newton, L. 1931. ''A Handbook of the British Seaweeds.'' British Museum][Burrows, E.M.1991. ''Seaweeds of the British Isles Volume 2 Chlorophyta''. Natural History Museum, London] Cells contain a single chloroplast
A chloroplast () is a type of membrane-bound organelle, organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. Chloroplasts have a high concentration of chlorophyll pigments which captur ...
, which is parietal and sometimes lobed. The chloroplast shape varies with age: in young cells, the chloroplasts tend to be shorter and covering less of the cell circumference. Chloroplasts typically have one to three pyrenoid
Pyrenoids are sub-cellular phase-separated micro-compartments found in chloroplasts of many algae,Giordano, M., Beardall, J., & Raven, J. A. (2005). CO2 concentrating mechanisms in algae: mechanisms, environmental modulation, and evolution. ''An ...
s.[
''Ulothrix pseudoflacca'' and ''Ulothrix consociata'' are considered to be forms of ''Ulothrix flacca'' by some biologists. Sometimes difficult to distinguish ''Ulothrix'' from ''Urospora''.]
Reproduction
''Ulothrix flacca'' may reproduce vegetatively by fragmentation of filaments. It also reproduces asexually or sexually; in both cases, vegetative cells (except for those producing rhizoids) develop into zoosporangia or gametangia, respectively. Zoosporangia are yellow-green, somewhat longer than vegetative cells. Each zoosporangium produces typically 8–32 zoospore
A zoospore is a motile asexual spore that uses a flagellum for locomotion in aqueous or moist environments. Also called a swarm spore, these spores are created by some protists, bacteria, and fungi to propagate themselves. Certain zoospores are ...
s; the zoospores are typically 6.6–10.6 μm long, spindle-shaped and with two flagella
A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many pr ...
, a cup-shaped chloroplast
A chloroplast () is a type of membrane-bound organelle, organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. Chloroplasts have a high concentration of chlorophyll pigments which captur ...
, pyrenoid
Pyrenoids are sub-cellular phase-separated micro-compartments found in chloroplasts of many algae,Giordano, M., Beardall, J., & Raven, J. A. (2005). CO2 concentrating mechanisms in algae: mechanisms, environmental modulation, and evolution. ''An ...
and a small stigma. Zoospores are released through an opening in the cell wall of the zoosporangium; after swimming, they attach to a hard substrate, lose their flagella, and germinate into new filaments.