Species Description: B. neritina is an erect, arborescent bryozoan whose colonies form brown or reddish tufts on whatever substratum they encounter. It is a common and abundant member of the fouling community (Winston 1995). Zooids are large and measure an average of 0.97 X 0.28 mm. Zooids alternate biserially on branches, with individual zooids tapering proximally. A membrane covers the frontal surface. B. neritina differs from other species in this genus in that it possesses no avicularia and no spines. Rather, its zooids have sharp points in the distal corners. The lophophore measures an average of 0.764 mm in diameter and bears 23 tentacles.
Regional Occurrence: B. neritina is a highly cosmopolitan and abundant species throughout warm water areas of the world and is considered a troubling fouling organism.
IRL Distribution: B. neritina occurs throughout the Indian River Lagoon and along the Florida coast.
Age, Size, Lifespan: Zooids are large and measure an average of 0.97 X 0.28 mm. The lophophore measures an average of 0.764 mm in diameter and bears 23 tentacles.
Abundance: B. neritina is one of the most abundant bryozoans in the IRL and an important member of the fouling community. It is most common in the winter months where it and B. stolonifera dominate bryozoan populations on hard substrata such as seawalls and docks (Winston 1995). It does however, show a fluctuating pattern of abundance. In some years it is a dominant species from late fall through late spring. In other years, it is sparsely distributed.
Reproduction: B. neritina has large ovicells that are attached to the distal corners of zooids and oriented at angles to the axis of the branch. In temperate waters, B. neritina reproduces in summer and fall. In the IRL, reproduction occurs in the cooler months. Older colonies appear to "over-summer." Winston (1982) reported that colonies collected coastally in June and July were brown in color and appeared to be nearly completely degenerated, with many zooids dead or filled with ciliates. However, closer examination revealed functional zooids present in the distal ends of the colony.
Embryology: Embryos brooded in ovicells are dark brown in color and measure approximately 0.25 mm in diameter (Winston 1982).
Temperature: Though B. neritina is eurythermal, it can be sensitive to cold. Winston (1982) reported that Bugula neritina colonies collected from intertidal areas of Sebastian Inlet after a cold event were all dead. This sensitivity to cold water temperatures may help to explain the fluctuating abundance pattern in this species.
Winston (1978) reported that B. neritina has apparently developed an adaptation for feeding on zooplankton. By twisting the ends of its tentacles together to form a cage of sorts, B. neritina is able to filter out active ciliates and other protists.
Trophic Mode: B. neritina, like all bryozoans, is a suspension feeder. Each individual zooid in a colony has 23 ciliated tentacles that are extended to filter phytoplankton less than 0.045 mm in size (about 1/1800 of an inch) from the water column. Bullivant (1967; 1968) showed that the average individual zooid in a colony can clear 8.8 ml of water per day.
Habitats: Typical habitat for ectoprocts in the Indian River Lagoon include seagrasses, drift algae, oyster reef, dock, pilings, breakwaters, and human-made debris (Winston 1995).
Associated Species: Seagrasses as well as floating macroalgae, provide support for bryozoan colonies. In turn, bryozoans provide habitat for many species of juvenile fishes and their invertebrate prey such as polychaete worms, amphipods and copepods. (Winston 1995). Bryozoans are also found in association with other species that act as support structures: mangrove roots, oyster beds, mussels, etc.
Special Status: None.
Benefit in IRL: Bryozoans are ecologically important in the Indian River Lagoon due to their feeding method. As suspension feeders, they act as living filters in the marine environment. For example, Winston (1995) reported that bryozoan colonies located in 1 square meter of seagrass bed could potentially filter and recirculate an average of 48,000 gallons of seawater per day.
Economic Importance: None.
Winston JE. 1978. Polypide morphology and feeding behavior in marine ectoprocts. Bull Mar Sci 28: 1-31.
Winston JE. 1982. Marine bryozoans (Ectoprocta) of the Indian River area (Florida). Bull Amer Mus Nat Hist 173: 99-176.
Winston JE. 1995. Ectoproct diversity of the Indian River coastal lagoon. Bull Mar Sci 57: 84-93.