Penicillus spp

Family: Udoteaceae


Stocking Island, Great Exuma, Bahamas, Western Atlantic, 1m, 5 February, 2004. Photo: Marina Poddubetskaia

Penicillus is a genus of green algae commonly called Shaving Brush Plants or Neptune's Shaving Brush because of their shape. A common Caribbean genus, they are found in seagrass beds and sand flats along with Halimeda and Udotea. Like Halimeda and Udotea, Penicillus belongs to the Family Udoteaceae, and all three genera have a stalk, or holdfast, to anchor them in the sand. The plants also become calcified to varying degrees as they grow, which protects them from many herbivorous animals. Penicillus dumetosus can reach about 10-15 cm in height and is lightly calcified which stiffens the plant allowing it to stand upright.

They are fed on by some sacoglossans, herbivorous opisthobranchs which feed by sucking the cell contents from their preferred algae. We are not sure of the algal preferences oof many species, but it seems that Elysi papillosa prefers species of Penicillus and Udotea.

Authorship details
Rudman, W.B., 2004 (February 19) Penicillus spp. [In] Sea Slug Forum. Australian Museum, Sydney. Available from