Purse Sponge

Grantia compressa

Grantia compressa, known as the purse sponge, is a calcareous sponge species commonly found along the rocky shores of the Atlantic coasts of Europe, from France northwards. Divers can identify this sponge by its distinctive flattened, purse-shaped vases that can reach up to 5 cm in length. These structures are attached to rocky overhangs by a stalk and often hang downwards in groups among seaweed. The sponge's color ranges from grey to yellow, and its body resembles a branching tree with slender, vase-like cylinders measuring 5 to 6 mm in diameter. The surface is pierced by numerous inhalant pores, or ostia, and features a large osculum encircled by an oscular fringe at the free end of each cylinder. The purse sponge thrives in temperate waters of the Northeast Atlantic and Northeast Pacific. It is typically found in shallow waters, with most occurrences recorded at depths shallower than 40 meters, and often inhabits rocky reefs and caves. As a sessile organism, it attaches itself to substrates and remains stationary, filtering water to feed. Reproduction in Grantia compressa involves both asexual and sexual methods. It can reproduce asexually through regeneration and budding, while sexually, it is hermaphroditic. The life cycle includes a free-swimming larval stage before settling down to grow into a mature sponge. Currently, there is no specific conservation status for this species, but it is considered common in its habitat.