Chlorophyta, Green Algae
Chaetomorpha Kützing, 1845
Chlorophyts, Order: Cladophorales; Family: Cladophoraceae.
Chaetomorpha, means ‘hair-like’. The name refers to the untangled form of the plant, which resembles string.
The Chaetomorpha resembles a cluster of green filaments. A microscope is needed to identify the genus and the species. The Chaetomorpha has one long row of cells, but no secondary branching, unlike the Cladophora. Species vary in accordance with the size of the cells, with the relationship between a cell’s length and breadth, and with the thickness of the cell wall. Cells are comparatively large, and the cell walls are thick.
The Chaetomorpha reaches several centimetres in length (sometimes dozens), and their width is less than half a millimetre.
Chaetomorpha species are green, ranging from dark-green to greenish-yellow.
Unlike other delicate green algae, the Chaetomorpha thallus is never branched.
Various species of Chaetomorpha differ in habitat. Some species may be found in the subtidal zone and some in Chaetomorpha aerea, a spore-bearing segment of the thallus. areas often exposed to air. Sometimes the location of the algae is influenced by herbivores.
Biology and reproduction
The simple structure that includes a single row of cells with no branching indicates a relatively rare and primitive form among macroalgae. This is also evident in another species that grows in fresh water -Ulothrix. The genus undergoes an isomorphic life cycle, in which reproduction occurs through bi-zoosporic cells that are discharged from formless cells - another indication of the primitiveness of the species.
Seasonality and distribution
Some species can be found along the coast throughout the year, and others are seasonal. Some species manage to develop in polluted areas that are rich in nutrients. The genus is widely distributed and includes about thirty
species, some with a global distribution; some species however, are endemic.
Due to its simple structure a taxonomy of species is quite difficult. The classification is mainly on the basis of microscopic measurements of cell length. Since the colony is wild and the cells are alive, there are differences in size (even in the same individual) at different stages of development and in accordance with changing environmental conditions. Often the size of some cells in one individual is congruent with the size of those of a different species, and classification is nearly impossible. The species common in our region is probably Chaetomorpha aerea (Dillwyn) Kutzing . Its fibres reach a length of 20 cm and, through a microscope, cells of 1 mm length by 0.35 mm width are apparent. Other species also exist in the area.