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Chlorophyta, Green Algae

Ulva (Enteromorpha) Link 1820

Chlorophyta, Order: Ulvales; Family: Ulvaceae. It has recently been suggested that the Enteromorpha genus be combined with the Ulva genus (Hayden et al., 2003). In this book, we have held by the traditional system, and the two appear as separate genus.


Enteromorpha, refers to the shape of the thallus’ tube, which resembles an intestine.


Enteromorphas are green algae, connected to the substrate through a disk. The thallus is made of 2 hollow layers, resembling a tube or an intestine, at least in its upper part. Precise identification requires a lateral slice 1 cm from the holdfast. Sometimes, the tube opens and a flattened, single- layered shape is the result. Sometimes, branching of the thallus to a greater or lesser extent is evident. Sometimes, proliferation (a delicate sharpening at the thallus’ edge) can also be observed.


Different species have different sizes. The algal size also depends upon the breeding conditions and upon the presence of herbivores.


Various shades of green, from warm, yellowish-brown to blue- green, depending upon the light conditions in the habitat.

Special features

It is easy to confuse Enteromorpha plants and Ulva plants. Microscopic examination of a lateral cross section near the base of the holdfast reveals that the Enteromorpha has two layers of attached cells (stuck together), but the Ulva have two layers that are separated by an empty space. The two species cannot be distinguished in the field, and one or more cross sections and microscopic examination for definite identification must be made.


Most Enteromorpha individuals found in the Eastern Mediterranean develop in the intertidal zone, in the wave- breaking area. Some develop above the intertidal zone, and they are moistened by wave activity.

Biology and reproduction

See details in Ulva.

Seasonality and distribution

Species of Enteromorpha can be found along the coast throughout the year. In the Mediterranean, there are about twenty species.

Additional species

In the Mediterranean there are over twenty species of Enteromorpha. They are divided into groups, in each of which there are a number of variants of species. The parameters for classifying Enteromorpha are the same as those for classifying Ulva. Since we still have no updated and authoritative list of Enteromorpha species, I shall describe the most common ones and add information on those found in the region (after Longo and Giaccone, 1994). The Enteromorpha species that appear in this list are species referred to in various publications from the region, or that have been positively identified:

Enteromorpha clathrata (Roth)  Greville Enteromorpha compressa (Linnaeus)  Greville Enteromorpha flexuosa (Wulfen) J. Agardh Enteromorpha intestinalis (Linnaeus) Nees Enteromorpha linza (Linnaeus) J. Agardh Enteromorpha prolifera J. Agardh Enteromorpha ramulosa (J. E. Smith) Carmichael

Three additional species have been described in a single publication originating in Lebanon, and we have accordingly included them in the index, although we have not described them in detail.

Enterommorpha aragoensis Bliding An alga with a simple, tubular thallus, filamentous and without branching. From above, the cells can be seen arranged in lateral lines, although not throughout, The cells are rectangular, differ in shape, and the chloroform resembles a tooth. They have 3-6 Pyrenoids. Distributed throughout the Mediterranean.

Enteromorpha hendayensis Dangeard and Parriaud A rare species in the Mediterranean, besides the one Lebanese report, it is known only in Spain.

Enteromorpha ralfsii Harvey A plant with a filamentous, unbranched thallus. The cells are rectangular or square and arranged in a lateral line. The

chloroplast resembles a lobe with several Pyrenoids - usually 2-5 and sometimes 8. The species is most common in the Atlantic Ocean.


Look for Key to species of Ulva and Enteromorpha


 The consumption of Enteromorpha and its use to purify water resembles the utilization of Ulva. See details under Ulva. In Japan the Enteromorpha is used to treat cysts, hemorrhoids and intestinal ailments.

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