Sand Mason

• Its tubes, packed at thousands of individuals per square metre, stabilise the sediment and create a raised habitat that houses a whole community of small invertebrates and serves as a feeding ground for flatfish and waders.
• The crown of sand at the top of the tube acts as a miniature breakwater and generates small eddies that trap the particles it feeds on.
• Its beds are one of the soft-bottom habitats recognised as of conservation interest in the European Atlantic.
• It builds a tube of sand and shell fragments glued with mucus, topped by a frayed crown that protrudes from the sand and gives it the look of a worn-out brush.
• That crown is not decorative: it slows the current just above the bottom and makes the particles it feeds on settle out.
• It is an ecosystem engineer. Its dense aggregations stabilise the sediment, create relief and multiply the biodiversity of the seabed: many more species live beneath a field of these tubes than in bare sand.
• That is why its biogenic reefs are recognised as a habitat of interest under European legislation.
• It alternates two ways of feeding: it spreads its tentacles over the surface to gather detritus, or raises them into the current to filter, according to what is on offer.

Skeleton type

Invertebrate - no rigid skeleton (annelid)

Habitat and environment

Intertidal and subtidal sands of the north-eastern Atlantic and the Mediterranean

Sources consulted: Pallas (1766) · Rabaut et al. (2007) · Marine Life Information Network · Joint Nature Conservation Committee · ScienceDirect (Hughes 1989) · Science Advances, How colonial animals evolve · Wikipedia, Zooid