Diving bryozoans in Marseille National Park of the Coves

The Bryozoans

Bryo-Porella Cervicornis-CorneCerf-Tiboulen-35m-08-07-04 (1) Bryo-Pentapora Fascialis-CorneElan-PteLuque-20m-02-05-04 (2) Bryo-Myriapora truncata-FauxCorailRouge-PteLuque-20m-02-05-0 Bryo-Adeonella Calveti-MoyadeMer-15m-30-05-04-VMSG1

Number : 5 000 species described, of which 180 in the Mediterranean.


Spreading, encrusting or erect, tree, spinescent, rigid or gelatinous Colonies attached to the substrates of the ribs and seabed, from a few millimetres to max a few tens of centimeters (sea Rose).

The colonies consist of many individuals (zooids) with bilateral symmetry, almost independent, often in very regular rows (Membranipore).

Individuals are very small (less than 1 mm.: Need magnifying glass) and their polypide (tentacles and digestive tract) can retract for protection in a more or less calcified housing (the Cystidium).

The Crown of non-stingingable hollow tentacles is very characteristic: it is the lophophore.

Ecology :

It is one of the dominant rock-bottom groups with ascidians, sponges and cnidarians.

They are very afraid of the algae that can smother them: they are found, especially in the shade areas.

Generally little noticed and with no commercial value.

Criteria of recognition:

Easy for divers for a few colonies whose shape is characteristic (Bugule, Neptune lace), identification requires careful examination with binocular magnifier for many species.


No heart or differential system for breathing, no néphridie.

Relations Trophic :

Continuous passive water filtering, the particles (micro algae, protozoa) are captured by the vibration eyelashes of the tentacles (which are themselves motionless) and then directed to a well-differentiated digestive tract.

Digestion by stomach and intestine, evacuation by an anus giving outside the lophophore. The bryozoan are the defenseless prey of numerous sea slugs, small crustaceans and some sea urchins.

Reproduction :

Simultaneous bisexual, ciliate larva. Very important budding Reproduction.

Evolution : Resemblance of bryozoans larvae with annelids larvae. The colonies of bryozoans resemble the colonies of Hydrozoans (cnidarians), but the individuals are very different: digestive tract for example!

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