{"id":9201,"date":"2014-03-02T09:19:33","date_gmt":"2014-03-02T07:19:33","guid":{"rendered":"http:\/\/klqewmpxo.cyon.link\/?page_id=9201"},"modified":"2026-03-31T22:40:40","modified_gmt":"2026-03-31T19:40:40","slug":"moostierchen","status":"publish","type":"post","link":"https:\/\/azalas.de\/en\/bryozoa\/","title":{"rendered":"Bryozoa"},"content":{"rendered":"

B<\/big>ryozoans or moss animals form their own phylum among the Lophotrochozoa<\/em>, a group of animals that mainly comprises various worms; however, the exact systematic relationships are still unclear. Bryozoans are tiny, multicellular animals that form colonies that either lie on the substrate in a crust-like form or grow upwards in a shape resembling a veil, an antler or a fan. Moss animals grow on rocks and stones, but also on the shells and carapaces of living animals (snails, mussels, etc.) or on plants.<\/p>\n

T<\/big>he individual animals (zooids) of a bryozoan colony are no more than half a millimeter in size. They consist of the polypide (front body) with a small ring of tentacles, which are used to capture food, and the cystid, the rear body, into which the polypide can retreat. The cystids have a calcareous or chitinous shell, which can often be closed with a small lid. The animals have a simple gastrointestinal tract, muscles and a nervous system. The mouth opening is located in the middle of the tentacles; gas exchange takes place via the tentacles.<\/p>\n

B<\/big>ryozoa are sometimes hermaphrodites, sometimes they turn male and female at different stages of their life. The sperm is released into the seawater via the ends of special tentacles. In many species, the eggs remain in the mother’s body for fertilisation in a special brood chamber, where the first stages of embryonic development also take place. The larvae swim around freely for a while and then settle down to form a new colony. The colony grows from the first animal through budding (asexual reproduction).<\/p>\n

W<\/big>ithin a colony, the various individual animals are connected to each other through small openings in their shells. Some of the zooids take on special functions: in free-growing species, for example, the individual animals that form the stem sometimes lose their tentacles. Some animals in the colony are so-called vibracularia, whose polyps are equipped with flagella. They create a water current on the surface that prevents the deposition of sediment on the colony. The avicularia, which are shaped like small gripping pincers, prevent other sessile organisms from attaching themselves and keep the colony clean. Fertilisation and brood care also take place in specialised individual organisms, the gonozooids. Considering the specialisation of the individual zooids and the fact that all individuals in a colony are clones, i.e. genetically identical, one could almost regard the moss animal colonies as separate individuals, i.e. a \u2018superorganism\u2019.<\/p>\n

A<\/big>round 5,600 species of bryozoans have been described, some living in the sea and some in fresh water. Around 180 species are known to exist in the Mediterranean. They can usually only be identified under a microscope, except for free-growing (not crustose) species whose colonies often show a characteristic shape and colour. In dead organisms, the shells may be so worn that features which are important for the identification, such as small spines on the cystid, are no longer recognisable.<\/p>\n

\"Bryozoa
\nIn this colony of moss animals the tiny cystids with their openings are visible.<\/small><\/p>\n

\"Bryozoa
\na better-preserved colony<\/small><\/p>\n

\"Bryozoa
\nBryozoans grow not only on stones and rocks, but, as here also on organisms such as seagrass.<\/small><\/p>\n

\"Bryozoans\"
\nHere one can see several species of moss animals with very different growth forms on the rhizomes of seagrass, including at least two that grow in a crust-like manner: the brownish crust in the centre with its very regularly arranged zooids, and the white crust with rounder zooids on the small twig at the bottom right; further a small, rounded, slightly raised colony at the bottom right, and finally a free-growing, branched species in the lower left-hand part of the image.<\/small><\/p>\n

\"Moss
\nIdentifying the species is usually impossible without special identification literature. The brownish, regular crust could, for example, belong to the species Schizobrachiella sanguinea<\/em>.<\/small><\/p>\n

\"Moss
\nThis species grows in a small, \u2018mound-shaped\u2019 colony surrounded by a distinct rim; the zooids are irregular in shape and size and show small pores; unfortunately, I cannot find a matching species in the literature available to me.<\/small><\/p>\n

\"bryozoans\"
\nThe free-growing, branched species could be Scrupocellaria scrupea<\/em>.<\/small><\/p>\n

Only two of our species have such a characteristic appearance that they can be identified with certainty:<\/p>\n

Electra posidoniae<\/em>, Gautier<\/h6>\n

T<\/big>he moss animal species Electra posidoniae<\/em> is one of the easily identified species due to the characteristic shape of the colonies and the cystids and because it only grows on the Neptune grass.<\/p>\n

\"Electra
\nElectra posidoniae<\/em> grows on the leaves of Neptune grass. It is very common in the Mediterranean. The individual animals are arranged in rather loose rows and appear almost transparent, as the upper part of the shell is not calcified.<\/small><\/p>\n

Patinella radiata<\/em>, Audouin<\/h6>\n

T<\/big>he moss animal Patinella radiata<\/em> forms round colonies measuring up to half a centimeter with a marginal lamella; the zooids sit on radially arranged lamellae, in which the small pores, through which the animals are connected, are visible. The species occurs throughout the Mediterranean Sea from shallow water to a depth of 50 meters.<\/p>\n

\"Patinella
\nSometimes one can find a colony of Patinella radiata<\/em> on a stone or a shell; it slightly resembles the skeleton of a pig-tooth coral, but has a distinctive shape with the marginal and the radial lamellae.<\/small><\/p>\n

To the photo gallery<\/a><\/p>\n

continue: Marine worms<\/a> <\/p>\n

back: Marine animals (Overview)<\/a><\/p>\n

see also: <\/p>\n