LIFE CYCLE OF CAULERPA

Family Caulerpaceae:

Plants are coenocytic, branched, slenderly filamentous, or quite large and then differentiated into rhizoidal, stoloniferous and erect portions, the latter assuming a great variety of forms. The coenocyte has firm wall braced internally by a system of trabeculae.

Reproduction is by segregation of portions of the contents of a branch to form dimorphic swarmer’s, probably gametes, which are discharged through elevated papillae.

Genus Caulerpa :

All species of Caulerpa are marine being frequent in the quiet shallow waters of the tropics although there are some Mediterranean species. They cover extensive tracts of the sea-floor and favour relatively shallow water. Several of them are often rooted in sand or mud with their prostrate rhizome bearing colourless rhizoids with which they attach themselves with the substratum.

The production of deadly poisonous substance Caulerpicin has been recognized in Hawaii and in the Philippines, since freshly collected plants of Caulerpa eaten in salads causes health hazard.

THE PLANT BODY

The plant body is elaborate in form being differentiated into prostrate portion represented by creeping rhizome with rhizoids  and an aerial portion performing the function of assimilatory shoot, or assimilator which may be very variable in structure being either simple flat blade-like, or lobed or a highly complicated branched structure.

Internally, plant body is characterized by the complete absence of septation and is composed of closely apposed and intertwined coenocytic threads traversed by longitudinal and transverse skeletal strands perhaps to increase the rigidity of the plant body. These are very remarkably developed in the rhizome portion and are completely absent or poorly developed in the rhizoids.

As such the entire plant body is a single multinucleate cell with a central vacuole and lining cytoplasm with numerous discoid chloroplasts. The longitudinal walls, as well as the wall of the skeletal strands are composed of callose, pectin, and similar other materials. But cellulose is completely absent.

Sexual reproduction, depending on species, may be iso- or anisogamous by the production of biflagellate swarmer’s which are more or less .pear-shaped. They are developed in the entire body except the rhizoids. Prior to their liberation, papillate outgrowths are developed.

Simultaneously with the development of papillae there starts the formation of gametes in the plant body. Before the formation of papillae the assunilators acquire a variegated appearance.

The swarmer’s are liberated in a mass of mucilage through the apices of the extrusion papillae. In some species, soon after the liberation of swarmer’s the whole plant dies. In certain species the whole plant can produce swarmer’s, whilst in others the reproductive area is limited.

The swarmer’s in Caulerpa clavifera are of two kinds—the macro- and micro-gametes. Gametic fusion in Caulerpa is commonly anisogamous 

Some Indian species of Genus Caulerpa:

Caulerpa crassifolia (Ag.) J. Ag.; C .fastigiata Mont. ; C. peltata Lamour.; C. racemosa (Fursk.) Web. van. Bosse.; C. sertulariodes Gmel.; C. taxifolia (Vahl.) Ag.

Special Features of Genus Caulerpa:

1. Coenocytic plant body with remarkable differentiation of aerial and prostrate portions.

2. Development of internal skeletal strands for mechanical support of different parts of the plant body.

3. Sexual reproduction both iso- and anisogamous.

4. Fusing gametes are pyriform bearing two flagella.

5. Gametes escape from the plant body through the ends of extrusion papillae in a mass of mucilage.