Flustrellidra hispida (Fabricius, 1780)

General description: 

Flustrellidra hispida is an encrusting bryozoan, generally restricted to the mid or lower intertidal zone, in temperate environments. It is abundant on sheltered to moderately exposed rocky shores, where it forms thick dark brown to purplish patches with a distinctly hairy or furry feel. It primarily colonises Fucus serratus, but may use other algal substrates such as Chondrus crispus, Gigartina stellata and Ascophyllum. Only very rarely does F. hispida colonise hard substrates.

The species is widely distributed and may be found on all British coasts.

Growth: 

Colonies grow through asexual budding of new zooids at the periphery. Growth of young colonies is rapid throughout the summer months.

Morphology: 

Fluestrellidra hispida forms thick encrusting patches or cylindrical colonies, which are dark brown to purple with a furry feel. Zooids are oval to hexagonal in shapes and are separated by deep grooves. Zooids are completely membranous with no calcification. The frontal membrane is smooth and translucent such that the polypide is visible as a white streak. The rectangular orifice of the zooid is subterminal and is wider than it is long. Tentacle number appears to vary between different populations, but is commonly between 28 and 40. Around four to six specialised zooids, which lack feeding apparatus, (kenozooids) develop as erect spines with a blister-like base. The spines are arranged in arc around the distal end (furthest from the colony origin) of feeding zooids and are typically between 0.4-0.6 mm long. They are responsible for the furry feel of the colony

Size: 

The size of zooids is between 0.8 and 1.2.6 by 0.5 and 0.6 mm

Associations: 

Flustrellidra hispida is able to colonise algal substrates, primarily Fucus serratus, but it may use other algal substrates such as Chondrus crispus, Gigartina stellata and Ascophyllum.

Distribution: 

Flustrellidra hispida is a temperate species. In the eastern Atlantic, it ranges from the White Sea and Arctic Norway to the north west coasts of France. In the western Atlantic it ranges south to Woods Hole

Habitat: 

Flustrellidra hispida is abundant on sheltered to moderately exposed rocky shores. It reaches its greatest abundance on Fucus serratus, but may use other algal substrates such as Chondrus crispus, Gigartina stellata and Ascophyllum. Only very rarely does F. hispida colonise hard substrates. It is mainly found in the mid to lower shore, hardly extending into subtidal waters.

Life cycle: 

The founding zooid (ancestrula) develops into a young colony, and later into an adult colony through asexual budding. Sexually produced embryos are brooded within the colony. Larvae settle after liberation and metamorphose into an ancestrula.

Trophic strategy: 

Like all bryozoans, Flustrellidra hispida is a suspension feeder. It feeds on small phytoplankton using ciliated tentacles of the lophophore.

Reproduction: 

Reproduction in Flustrellidra hispida occurs during winter. By February, developing embryos, brooded within the colony may be observed by the naked eye as distinct yellowish-white patches. Larvae are non-feeding coronate larvae, which lack a shell and have a densely ciliated belt (the corona) for locomotion. The larvae are large relative to other bryozoan larvae and settle from April to August, depending on location.