B. gracilis colonies are generally pale yellow to tan in color and form tangled masses in hydroids, algae, seagrasses, or other substrata (Winston 1982). Zooids are tubular in shape and are attached basally to the stolon where they are arranged either alone, in pairs, or in clumps. Stolon width measures approximately 0.05 mm in diameter. Individual zooids differ in size depending on whether the lophophore is extended or not, measuring approximately 0.6 mm X 0.12 mm while expanded. Retracted zooids are shorter and are generally observed to be flattened against the substratum. The lophophore is not pigmented and measures approximately 0.315 mm in diameter. It bears 8 tentacles and shows a great deal of flexibility while actively feeding (Winston 1978).

Atlantic, Bar Road, Belgian Exclusive Economic Zone, Belgium, British Isles, Calais, Cobscook Bay, European waters (ERMS scope), Gulf of Maine, Gulf of Mexico, Irish Exclusive economic Zone, Minas Basin, New Zealand Exclusive Economic Zone, North West Atlantic, Oosterschelde, Portuguese Exclusive Economic Zone, Ria de Aveiro, Saint Andrews, Spanish Exclusive Economic Zone, United Kingdom Exclusive Economic Zone, USA, Wimereux, Zeeland

southern Gaspe waters (Baie des Chaleurs, Gaspe Bay to American, Orphan and Bradelle banks; eastern boundary: Eastern Bradelle Valley); middle North Shore (from Sept- Iles to Cape Whittle, including the Mingan Islands); Florida

B. gracilis is most likely cosmopolitan in shallow water (Winston 1982). In the western Atlantic, its range extends from Greenland south to Brazil. B. gracilis is widely distributed throughout the Indian River Lagoon and along the Florida coast.

Individual zooids of live specimens taken from the IRL measured 0.38 - 0.80 mm in length (Average: 0.6 mm), and 0.9 - 0.14 mm in width (Winston 1982). The lophophore bears 8 tentacles and measures approximately 0.315 mm in diameter.

Known from rocky shores.

infralittoral and circalittoral of the Gulf and estuary

Depth range based on 48 specimens in 1 taxon.
Water temperature and chemistry ranges based on 5 samples.

Environmental ranges
  Depth range (m): 0 - 100
  Temperature range (°C): 9.788 - 12.863
  Nitrate (umol/L): 2.564 - 7.634
  Salinity (PPS): 30.381 - 35.192
  Oxygen (ml/l): 4.910 - 6.395
  Phosphate (umol/l): 0.418 - 0.731
  Silicate (umol/l): 2.391 - 16.169

Graphical representation

Depth range (m): 0 - 100

Temperature range (°C): 9.788 - 12.863

Nitrate (umol/L): 2.564 - 7.634

Salinity (PPS): 30.381 - 35.192

Oxygen (ml/l): 4.910 - 6.395

Phosphate (umol/l): 0.418 - 0.731

Silicate (umol/l): 2.391 - 16.169
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

B. gracilis, like all bryozoans, is a suspension feeder. Each individual zooid in a colony has 8 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.Both the polypide and the body wall of B. gracilis are highly flexible. With the polypide retracted, the zooid is compressed against the substratum; with the polypide expanded, the zooid elongates and rises to a vertical or diagonal position with respect to the substratum. B. gracilis holds its tentacles straight while feeding. The polypides slowly scan the water column in a circular motion in search of appropriately sized particulates. Adjacent lophophore in this species are well separated. Polypides of neighboring zooids may occasionally touch each other while scanning, but they will quickly withdraw.Habitats: Typical habitat for ectoprocts in the Indian River Lagoon include seagrasses, drift algae, oyster reef, dock, pilings, breakwaters, and man-made debris (Winston 1995). In the IRL, B. gracilis was found primarily on seagrasses, but also on wood, dead shells, and aluminum cans. Coastally, it was found on algae, dead shells, hydroids and on other bryozoans.

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.

Winston (1982) reported this species as the most common ctenostome in the IRL. It is collected year-round at coastal sites, and from December through June at IRL sites. Colonies having embryos are observed in March.Locomotion: Sessile

Eggs are brooded internally in B. gracilis, usually in zooids whose polypides have degenerated. Embryos are peach colored (Winston 1982).

The following is a representative barcode sequence, the centroid of all available sequences for this species.


There is 1 barcode sequence available from BOLD and GenBank.   Below is the sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen.  Other sequences that do not yet meet barcode criteria may also be available.


Download FASTA File

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 1
Specimens with Barcodes: 1
Species With Barcodes: 1

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.