Phaeophyta,  Order: Ectocarpales; Family: Ectocarpaceae.

Etymology

The generic name refers to the fact that the spores develop on or at the edges of the thallus filaments as separate appendages.

Description

The Ectocarpus is a tiny alga that can be examined only through a microscope. Its thallus is comprised of elongated cells that form split filaments. The edges of these turn into sporangia. Part of the plant spreads out and part is slightly erect. Green particles may be seen at the joints and at the base of the filaments. The filaments are mucousy and smooth.

Size

Large individuals measure a few centimetres. The filaments are less than a millimetre in width.

Colour

The alga ranges from dark brown - nearly black - to yellow. A single thallus appears transparent through a microscope.

Special features

Identifying species requires microscopic examination. In the field, the Ectocarpus resembles a pile of silk threads.

Habitat

Many species of Ectocarpus appear as epiphytes upon other algae and sea creatures. The rhizoids are capable of penetrating a host’s cells and gripping on to these. Ectocarpus sporangia often grow in the upper regions of the intertidal zone, where they are exposed to the air. Often, blue-green algae may be seen in the vicinity.

Biology and reproduction

The Ectocarpus is an oogamous plant, sexual reproduction occurring through reproductive cells that are equal in size and shape. Some, especially the females, may get stuck to a rock or host. Male reproductive cells float up to the female gametes, merge with them and begin to develop. Although the Ectocarpus is not very impressive externally, its importance to the intertidal ecological system is paramount, since many species of fish subsist upon it.

Seasonality and distribution

Ectocarpus plants are very common and can be found along the shore throughout the year. The species enjoys a wide global distribution, especially in warm seas.

Additional species

Several species of Ectocarpus have been reported in Egypt, Turkey and Lebanon. Very few reports emanate from Israeli shores, where six species have so far been reported. Nemlich and Danin, in their book on sea algae in Israel, describe Ectocarpus siliculosus (Dillwyn) Lyngbye = Ectocarpus confervoides Le Jolis. This species can be found throughout the year, and is apparently a most common Ectocarpus species throughout the Eastern Mediterranean. Tikva Edelstein, in her research on deep-sea algae, describes Ectocarpus virescens Thuret, a warm seas species found at depths of about 30 m.