About Grantia compressa (Fabricius, 1780)
Grantia compressa is a species of calcareous sponge in the family Grantiidae. It is very common on rocky shores along the Atlantic coasts of Europe, from France northwards. This sponge forms flattened, purse-shaped vase structures up to 5 cm long, with slit-like oscula at their ends. Individuals hang downward, attached by a stalk to rocky overhangs, and often grow in groups among seaweed. It is a pale sponge, with color ranging from grey to yellow. Its body has an overall branching tree-like shape, made up of slender vase-like cylinders that measure 5 to 6 mm in diameter. The entire body is pierced by numerous inhalent pores called ostia. The free end of each cylinder opens to the outside through a large osculum, which is surrounded by an oscular fringe. Grantia compressa reproduces asexually through regeneration and budding. Its development is indirect, with a free-swimming amphiblastula larval stage.
