''Ulothrix speciosa'' 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
littoral zone
The littoral zone, also called litoral or nearshore, is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark (which is rarely flood ...
.
Description
''Ulothrix flacca'' consists of greenish filaments attached to a substrate, which grow up to 12 cm long.
[Burrows, E.M. 1991. ''Seaweeds of the British Isles Volume 2 Chlorophyta.'' Natural History Museum London ] Filaments are robust, soft, straight when young, becoming curled at maturity. It grows in flowing or spreading tufts.
The filaments are unbranched but may end up becoming tangled. Cells are attached to a substrate via a differentiated basal cell, or intercalary cells which develop rhizoids. Cells are cylindrical, with swollen ends when older; the filaments may be occasionally in multiseriate rows. Cells are typically 14.8–63.6 μm wide, and 4.8-15.6 μm tall. Near the basal part of the filament, cells are often narrower and shorter. 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; older cells may have a more reticulate chloroplast. The chloroplast shape varies with age: in young cells, the chloroplasts tend to be shorter, and cover less of the cell circumference. Chloroplasts have one to six
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. A single nucleus is present per cell.
[
''Ulothrix speciosa'' 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. Gametangia develop from vegetative cells (except basal cells or cells with rhizoids), and mature gametangia are olivaceous. The gametangia release the gametes through the dissolution of the cell wall. Gametes are biflagellate, spindle-shaped to ovoid, with a cup-shaped chloroplast containing a pyrenoid, and a small eyespot. ''U. speciosa'' is ]dioecious
Dioecy ( ; ; adj. dioecious, ) is a characteristic of certain species that have distinct unisexual individuals, each producing either male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproduction is ...
, and isogamous
Isogamy is a form of sexual reproduction that involves gametes of the same morphology (indistinguishable in shape and size), and is found in most unicellular eukaryotes. Because both gametes look alike, they generally cannot be classified as ma ...
. The gametes fuse to form quadriflagellate zygotes, which form a single-celled sporophyte
A sporophyte () is one of the two alternation of generations, alternating multicellular organism, multicellular phases in the biological life cycle, life cycles of plants and algae. It is a diploid multicellular organism which produces asexual Spo ...
phase. The sporophyte stage produces up to 128 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 or