SHARE THIS PAGE ON

×

Sponges, bryozoans and ascidians on deeply overhanging lower shore bedrock or caves

Description of Sponges, bryozoans and ascidians on deeply overhanging lower shore bedrock or caves

Identity:

flag A1.447
creatorIdentity remo
creationTime 2017-08-16T16:38:12.993
lastMaintainerIdentity remo
modificationTime 2016-03-16T18:42:49
id 2736
imageSize 0 Bytes

Overhanging, and shaded vertical, bedrock on the lower shore and in lower shore caves, which is not subject to appreciable wave-surge, characterised by crusts of bryozoans including Umbonula littoralis, sponges such as Grantia compressa, Halichondria panicea, Scypha ciliata and Hymeniacidon perleve and the ascidian Botryllus schlosseri. On overhangs, the hydroid Dynamena pumila hangs in distinct form from overhanging rock. The barnacles Balanus crenatus, Balanus perforatus (sometimes at high densities) and Semibalanus balanoides, and the calcareous tube-forming polychaetes Spirorbis spp. and Pomatoceros triqueter can be present as well. Certain species which are generally confined to the sublittoral, including the anemones Metridium senile and Corynactis viridis, may be found in the lower shore caves and overhangs. Littoral species such as Actinia equina are also present. The only algae present are coralline crusts. The list of characterising species partly reflects the variation in the species composition between individual overhangs and caves although this biotope can have a high species richness. Situation: This biotope is found in the lower eulittoral and sublittoral fringe in less wave-surged conditions than that of unit A1.4461.