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Phaeophyta, Brown Algae

Cystoseira rayssiae Ramon

Phaeophyta,  Order: Fucales; Family: Cystoseiraceae.


Cystoseira, means chain of vesicles, and it describes the air pockets in the thallus. The Cystoseira rayssiae species was identified as an endemic species to this region by Dr. Edith Ramon and named after her teacher, Professor Tscharna Rayss, a researcher of algae and fungi from the Hebrew University in Jerusalem who was among the first to describe algae of the Eastern Mediterranean.


The species is much smaller than the Cystoseira compressa. Its branches are cylindrical or slightly flattened (the flattened branches have a delicate central vein). The toful, the condensation at the base of the branches is smooth. Central branches sometimes lack side branching. Upon maturing, differences in branch widths are discernable: younger branches are thinner and more cylindrical that mature ones. The holdfast is developed and contains several axes that lead to the branches.


The Cystoseira rayssiae is slightly smaller than the Cystoseira compressa. Most individuals are 10-30 cm long.


The Cystoseira rayssiae is coloured in shades of light brown and cream, sometimes uniformly, and sometimes spots can be seen. Upon drying, the thallus becomes darker.

Special features

The Cystoseira rayssiae is easily confused with other species of Cystoseira common to the intertidal zone. The Cystoseira rayssiae is more delicate, its branches are shorter, and there are no air vesicles.


Cystoseira rayssiae may be found in the upper regions of the intertidal zone, as well as in deeper water. Mostly, it is not exposed to the air and does not appear in places battered by strong waves.

Biology and reproduction

Upon the onset of growth, cavities containing reproductive cells appear on the thallus. These cells are irregularly dispersed along the branches, their density rising upon maturity, and they lend the mature branches a bumpy shape

-less smooth. Seasonality and distribution

Cystoseira rayssiae is apparently endemic to the Eastern Mediterranean: along Israeli coasts and maybe Egypt. Many individuals have been collected along the Israeli shore. The Cystoseira rayssiae is perennial, and each individual undergoes a complete life cycle over the course of a year. Large Cystoseira rayssiae branches develop along the coast at the beginning of winter, and by the end of summer attain their full size. These stipes complete sprouting their spores and shed them. The base of the branches is wide, bloated and shorter. They are about 1 cm in length and about 3 mm in width. They remain attached to the holdfast throughout the summer and autumn, at which point the branches regenerate through the winter.

Additional species

As mentioned above, the Cystoseira rayssiae is apparently endemic to the Eastern Mediterranean. The species is very common along Israeli shores and information about it has recently been published in scientific literature (Ramon, 2000), providing it with official status, beyond the description of Dr. Ramon in the Encyclopedia of Israeli Animals and Plants. Nemlich and Danin describe an unidentified species, Cystoseira sp. in their book, which seems to be Cystoseira rayssiae.

 Cystoseira rayssiae - tubular branches with dark stains evident: some are cryptoblasts (having hairy indentations) and some are reproductive cells.

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