Batrachospermum is a freshwater filamentous red alga of the family Batrachospermaceae. It is commonly known as frog spawn, as its gelatinous appearance resembles the spawn of a frog.
Salient Features of Batrachospermum
The salient features of Batrachospermum are as follows:
- The plant body is branched, filamentous, and gelatinous in texture.
- It appears as chains of delicate beads.
- The thallus is differentiated into a prostrate system and an erect system.
- The branches are of two types: branches of limited growth and branches of unlimited growth.
- Cells are connected to each other by pit connections, i.e., cytoplasmic connections.
- Many partial, discoid, or lobed chromatophores are present in each cell.
- Flagellate cells are completely absent.
- Asexual reproduction takes place by uninucleate monospores in the young gametophyte.
- Monospores are produced singly within globose sporangia called monosporangia.
- Sexual reproduction is of the advanced oogamous type.
- The female sex organs are flask-shaped and called carpogonia. The male sex organs are known as spermatangia.
- The zygote shows an elaborate post-fertilization stage, forming a cystocarp.
- Presence of a diphasic alternation of haploid gametophyte and a haploid carposporophyte.
- A juvenile or chantransia stage is seen in the life cycle.
Occurrence of Batrachospermum
Batrachospermum is a genus of about 50 species. It is widely distributed both in temperate and tropical regions.
Most of the species are freshwater in habit and prefer to grow in cool, shady, and well-aerated clean waters. Some species occur in rapidly flowing streams, being attached to sticks, stones, or similar other submerged objects.
Thallus Structure of Batrachospermum
The plant body of Batrachospermum is soft, branched, filamentous, and blue-green to purple, violet, and pink in color. The filament is of gelatinous texture, appearing as chains of delicate beads.
The thallus may reach up to 20 cm or more in height. It shows a heterotrichous habit and is differentiated into prostrate and erect systems. The prostate system serves to anchor the thallus to the substratum, while the erect system consists of whorls of branches that float freely in water.
The thallus is uniaxial. The primary axis consists of numerous elongated cylindrical cells arranged end to end in a single row.
The main axis is corticated and differentiated into nodes and internodes. Many branches arise in whorls from the upper ends of the cells just below the septa. The branches are of two types: branches of limited growth and branches of unlimited growth.
The branches of unlimited growth are produced singly and further differentiated into nodes and internodes like the main axis. The whorls of nodal branches of limited growth give Batrachospermum thallus a bead-like appearance. Such group of branches at each node is called a glomerule.
The basal cells of the lateral branches in the primary axis develop into narrow threads. These threads grow downward, enveloping the primary axis, concealing it completely, and forming a corticated appearance.
Cell Structure
The cells of the filament are uninucleate and contain several parietal, lobed chromatophores with pyrenoids. Sometimes the chromatophores are diffuse. Many pigments, such as chlorophyll-a, chlorophyll-d, and phycoerythrin-r, are present in the chromatophores.
Each cell is surrounded by a thick cell wall. Cytoplasm contains Golgi bodies, mitochondria, granules of floridean starch (reserve food), etc.
Growth of the Thallus
The growth of Batrachospermum takes place by the dome-shaped apical cell. The apical cell divides by transverse division and forms a series of segments towards the posterior side. These segments increase the length in the older portion of the thallus.
