Membranipora membranacea is a very widely distributed species of marine bryozoan known from the Atlantic and Pacific Ocenas usually in temperate zone environments. It may be known colloquially as the sea-mat or lacy crust bryozoan and is often abundantly found encrusting seaweeds, particularly kelps.
Size is variable but always thin and mat-like, with a single lacy encrusting form with rectangular zooecia
with a short pair of blunt 'horns' projecting from the front corners. The edges of the colony are usually wavy. Colour is typically white to pale grey. Most commonly found on the fronds of large seaweeds such as Laminaria
. This species does not have the ovicells
often seen on other bryozoans.
North Atlantic including the Baltic Sea
, English Channel
, Mediterranean Sea
and North Sea
. Also the North Pacific coastline of North America
to the California
Like other bryozoans, M. membranacea
is a colonial organism
that feeds on plankton extracted by the lophophore
. M. membranacea
prefers shallow marine habitats between the mid intertidal
to the shallow sublittoral
. It may also be found in brackish water.
has become an invasive species
in many places, and is believed to have a potentially negative impact on marine ecosystems by limiting the ability of the seaweeds to reproduce.