Description: The body of this sponge is orange to yellow in colour and the papillae are pale yellow. The sponge consists of a low, spreading cushion (up to 1 cm thick), with papillae projecting above the sediment covered body. The papillae are differentiated into inhalant and exhalant; the exhalant papillae are large, few in number and open at one end, and can be easily distinguished from the thinner inhalant papillae.

Habitat: This species is usually found on upward facing bedrock, or at a sediment/bedrock interface with the body of the sponge beneath a layer of sediment and the papillae projecting through it.

Distribution: A common species on western and southern coasts of the British Isles, also reported from the Arctic, Atlantic coasts of Europe, Mediterranean and N. America.

Similar Species: There are several other papillate sponges with which P. penicillus may be confused including several undescribed Polymastia species and Ciocalypta penicillus.

Key Identification Features:

• Pale yellow coloured papillate sponge
• Papillae differentiated into inhalant and exhalant.
• The surface of the sponge is clean, it does not trap silt, gravel or shell.

Distribution Map from NBN: Polymastia penicillus at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Polymastia penicillus at iNaturalist World Species Observations database.

WoRMS: Polymastia penicillus at World Register of Marine Species. Accepted name: Polymastia penicillus (Montagu, 1814). AphiaID: 170654.

Classification: Biota; Animalia; Porifera; Demospongiae; Heteroscleromorpha; Polymastiida; Polymastiidae; Polymastia