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Species Name:    Crisia elongata
Common Name:                (None)

 

I.  TAXONOMY

Kingdom Phylum/Division: Class: Order: Family: Genus:
Animalia Ectoprocta Gymnolaemata Cyclostomata Crisiidae Crisia


SEM of Crisia elongata showing pattern of faint annulations. At left is an enlarged gonozooid.  Photo by J. Winston, courtesy of the American Museum of Natural History. Used with permission.  



SEM of C. elongata showing growth pattern of the tubular zooids.  Photo by J. Winston, courtesy of the American Museum of Natural History.  Used with permission.  

 

Species Name:
Crisia elongata Milne Edwards, 1838

Voucher Specimen: 
American Museum of American History # 633

Common Name:
None

Species Description:
Colonies of C. elongata form bushy white tufts that attach to hard substrata as well as to hydroids, algae and sponges. Individual zooids are tubular in shape and punctate, sometimes with annular striations apparent. They measure an average of 0.07 X 0.60 mm. The peristome is short and turned outward, often with a small denticle on the distal border. Zooids alternate on branches to form internodes, with approximately 14 16 zooids comprising an internode. Internodes are connected via brown to black joints comprised of chitin. The lophophore averages 0.266 mm in diameter and bears 8 tentacles. The mouth is tiny and round, averaging only 18 um in diameter (Winston 1978).

Synonymy:
Crisia eburnea form denticulata Smitt, 1872;  Crisia denticulata Osburn 1914

Other Taxonomic Groupings:
Suborder: Articulata


II.  HABITAT AND DISTRIBUTION 
Regional Occurrence:
C. elongata is a circumtropical species. In the western Atlantic, it occurs from Florida through the Gulf of Mexico and the Caribbean.

IRL Distribution:
C. elongata is a common fouling organism collected year-round at coastal locations in Florida. Winston (1982) found it to be a dominant species in the lower intertidal zone in the vicinity of Ft. Pierce Inlet.


III.  LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan:
Zooids of C. elongata measure an average of 0.07 X 0.60 mm. The lophophore averages 0.266 mm in diameter and bears 8 tentacles.

Abundance:
C. elongata may be collected year-round at coastal locations from Sebastian Inlet to Seminole Shores, however, it is most common from Winter through Spring. This species is far less abundant in the summer months, but young colonies do occur. Winston (1982) reported that polypides may not be functional in the summer. Zooids collected in summer appear to be oversummering, having their peristomes extended, and openings occluded by diaphragms.

Locomotion:
Sessile

Reproduction:
Colonies grow vegetatively throughout the Fall. Gonozooids begin developing by December, and embryos are present in January and February.

Embryology:
Gonozooids are short and broadly inflated, with a slight annulated surface. Oeciopore is a transverse slit located behind the distal end of the gonozooid. Mature larvae are ovoid and ciliated, greenish white in color and lacking pigment spots. Gonozooids with embryos and developing larvae are yellow to brown in color.


IV.  PHYSICAL TOLERANCES
Temperature:
The range of C. elongata is confined to the warm waters of the tropics and subtropics. However, it occurs year-round in Florida waters, and is thus able to withstand seasonal changes in water temperature.

Salinity:
C. elongata is typically collected from areas where salinity exceeds 30 .


V.  COMMUNITY ECOLOGY
Trophic Mode:
C. elongata, 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.

C. elongata feeds almost passively, filtering particles as they pass along the tentacles. While feeding, it rarely directs the lophophore, or flicks the outer ends of its tentacles as has been observed in other species. Microscopic examination showed that the laterofrontal cilia on the tentacles are quite long, and nearly fill the spaces between adjacent tentacles when the lophophore is fully expanded. The ciliation pattern on the lophophore forms an effective network that is able to filter out most particles larger than 2 mm (00007.87 inches). Additionally, the abundance of C. elongata among colonies of sponges and tunicates may be indicative of the ability of this species to take advantage of currents generated by other organisms.

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). C. elongata attaches to the roots of hydroids such as Thyroscyphus and Eudendrium in winter and early spring. It also grows well on sponges.

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.


VI.  SPECIAL STATUS
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

 

Report by:  K. Hill, Smithsonian Marine Station
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Page last updated: July 25,  2001