Spaghetti Bryozoan
(Zoobotryon verticillatum)

Description: This colonial animal forms transparent to white or yellowish bushes comprised of spaghetti or straw-like stalks that can be up to 45 cm long. This bryozoan superficially resembles an alga, but is paler than most, and close examination reveals tiny clusters of animal tentacles along the branches.

Habitat: The spaghetti bryozoan is found on hard substrates in bays and harbors. Large bushes are formed only when water warms to 22°C and above, although the colonies can overwinter during colder periods. Elevated temperature and salinity has been suggested to enhance outbreaks of this bryozoan.

Origin: Unknown; worldwide distribution in tropical and warm temperate seas.

Invaded Areas: On our coast, the species was introduced to San Francisco and Southern Californian bays; probably much of worldwide distribution is due to human-mediated introductions.

Concerns: The spaghetti bryozoan can form huge aggregations under optimal conditions. In 1905 large masses were reported in San Diego, and in 1992 it was found in San Francisco Bay. In Galveston, Texas, such abundant growth is known to negatively affect local fisheries by fouling fishing gear. The bushes of this animal tangle nets, and also block escape hatches for sea turtles. Colonies of this animal could also crowd out native sessile organisms and affect food webs in the water column by their active suspension feeding.