Yellow Clathrina

• Its skeleton is made of three-pointed calcium carbonate spicules, quite unlike the silica spicules of most sponges.
• The calcareous sponges are an ancient group of very simple anatomy, without the complex canal systems of the larger sponges.
• It has no organs, no nerves and no muscles: its cells work almost independently, and a sponge broken apart can reorganise itself and re-form as an individual.
• Its skeleton is made neither of silica nor of spongin like that of most sponges, but of calcium carbonate spicules. The calcareous sponges are the only group that does it that way.
• Its shape is unmistakable: a tangle of interconnected yellow tubes, like a bundle of macaroni.
• It belongs to an ancient group that matters in phylogeny: the calcareous sponges split early from the rest, and their position has been decisive in the debate over which was the first animal lineage.
• It lives in shade because it cannot withstand competition for space with algae.

Skeleton type

Invertebrate - calcareous spicules (sponge)

Habitat and environment

Shaded areas of the intertidal and shallow subtidal of the Atlantic and the Mediterranean

Sources consulted: Schmidt (1864) · Marine Life Information Network · Manuel et al., revisiones de Calcarea · Anatomia de Porifera, clase Calcarea