Yellow Hedgehog Sponge

Polymastia boletiformis

The yellow hedgehog sponge, Polymastia boletiformis, is a distinctive sponge found in the Arctic and North Atlantic Oceans. It forms small, cushion-like structures up to 10 cm in diameter, with hollow cylindrical papillae extending up to 3 cm from its surface. These papillae, which have exhalant openings at their tips, are the same yellowish-grey, yellow, or orange color as the rest of the sponge, making it distinguishable from similar species. The sponge's texture is smooth and firm, yet supple, and its papillae can contract when touched. This species inhabits temperate and cold waters, extending from the Gulf of Maine to the Bay of Biscay, and is commonly found in Northern France, the Netherlands, and the British Isles. It typically resides on the upper surfaces of boulders and rocks covered with sediment, often in association with bryozoans and hydroids. It can be found from the littoral zone down to depths of about 30 meters, though it has been recorded much deeper. As a filter feeder, the yellow hedgehog sponge draws water through its body to capture bacteria and phytoplankton. It reproduces sexually in the summer, releasing larvae into the water. The dorid nudibranch Doris adrianae is known to feed on this sponge. Its conservation status has not been evaluated.