Voucher Specimen: American Museum of Natural History # 610
Species Description: W. cucullata is a calcified, encrusting bryozoan. Its colonies are variable in appearance, and may be unilaminar and encrusting, to bilaminar and frilled. Living specimens are brownish orange to black. Polypides are bright orange-red. Zooids are large, and irregularly shaped, measuring an average of 0.82 X 0.38 mm in size. The frontal surface is curved and evenly perforated by large pores. The orifice is oval anteriorly with a small semicircular sinus which lends an overall mushroom-shaped appearance to the orifice. The operculum is generally dark brown to black. No avicularia are present. Average lophophore diameter is approximately 0.66 mm. An average of 21 tentacles is present on the lophophore.
Other Taxonomic Groupings: Suborder: Ascophora
Regional Occurrence: W. cucullata synonymy is very confused, however, this species appears to be highly cosmopolitan in warm waters. In the western Atlantic, it ranges from Florida south to Brazil, including the Gulf of Mexico and the Caribbean.
IRL Distribution: W. cucullata is the most common encrusting bryozoan along the coastline.
Age, Size, Lifespan: Zooids measure an average of 0.82 X 0.38 mm in size. Lophophore diameter is approximately 0.66 mm. An average of 21 tentacles is present on the lophophore.
Abundance: W. cucullata is one of the most abundant bryozoan species in the IRL and along the coast of Florida. It is also among the most common fouling organisms in this area. It is present year-round, but is most abundant in the winter months. Its success as a fouling organism is attributed to its rapid growth rate and its ability to grow on nearly every hard substratum including those coated with copper antifouling paint (Wisely 1958 in Winston 1982). W. cucullata is most abundant on the rocks of breakwaters at or near the mean low water level.
Reproduction: W. cucullata reproduces from November to April, with peak abundance of larvae in November and December.
Embryology: No ovicells are present in this species. Rather, embryos are brooded in internal ovisacs.
Temperature: W. cucullata is present in the IRL and along the coast year-round, and thus may be considered eurythermal.
Salinity: In the IRL, W. cucullata is commonly collected in areas where salinity falls below 30‰
Trophic Mode: W. cucullata, like all bryozoans, is a suspension feeder. Each individual zooid in a colony has 21 ciliated tentacles which 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.
Competitors: W. cucullata, like other encrusting types of bryozoan, competes for space with other groups of attached organisms such as algae and hydroids. In calm waters, or in areas where competition for space is intense, W. cucullata grows as bilaminar frills. In high energy areas, or where there is less competition for space, it grows as unilaminar crusts.
Habitats: Typical habitat for ectoprocts in the Indian River Lagoon include seagrasses, drift algae, oyster reef, docks, pilings, breakwaters, and human-made debris (Winston 1995). W. cucullata is common on the rocks of breakwaters, and is the only encrusting bryozoan that grows on "wormrock," the cemented sand tubes of Phragmatopoma lapidosa, the reef-building sabellarid.
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 supporting substrata: 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