Species accounts

Marine colonial entoproct

Barentsia discreta

ORDER Coloniales

FAMILY Barentsiidae

TAXONOMY

Ascopodaria discreta Busk, 1886, Nightingale Island, Tristan de Cunha.

OTHER COMMON NAMES None known.

PHYSICAL CHARACTERISTICS

Total length of each zooid up to 0.4 in (9.5 mm), usually 0.1-0.2 in (3-6 mm). Tentacles number about 20. Stalk is thin and long, about three to eight times longer than calyx, with many tiny pores, and a muscular swelling at base of stalk. Each zooid of a colony is interconnected by a stolon.

DISTRIBUTION

Cosmopolitan, but not in northern Europe. Ranges from shallow coastal zone to deep seas of more than 1,640 ft (500 m).

HABITAT

On any nonliving substrata, including rocks, stones, and dock pilings, as well as on living substrata, such as worm tubes.

BEHAVIOR

In response to a disturbance, it bends from basal muscular swelling, but the stalk itself does not curve. Action of one individual leads actions of surrounding zooids.

FEEDING ECOLOGY AND DIET

Suspension feeder. Feeds on phytoplankton and organic particles.

REPRODUCTIVE BIOLOGY

Buds at tips of developing stolon. Single colony contains both male and female zooids. Embryos brooded at brood pouch. Larva trochophorelike.

CONSERVATION STATUS Not listed by the IUCN.

SIGNIFICANCE TO HUMANS None known. ♦

Species Biology

Freshwater colonial entoproct

Urnatella gracilis

ORDER Coloniales

FAMILY Barentsiidae

TAXONOMY

Urnatella gracilis Leidy, 1951, Schuylkill River, Pennsylvania, United States.

OTHER COMMON NAMES None known.

PHYSICAL CHARACTERISTICS

Height of the colony is 0.08-0.12 in (2-3 mm), and each zooid has 12-16 tentacles. In addition to a basal muscular swelling common to Barentsiidae species, numerous muscular swellings are present throughout the stalk. One or two original stalks erect from a basal plate, successive stalks branch from older stalks. Calyx at tip of each branch of stalk. No interrupting stolons.

DISTRIBUTION

Belgium, Germany, Hungary, Romania, Russia (Don River), India, Japan, Africa (Nile River, Congo River, and Lake Tanganyika), United States, South America (Parana and Uruguay Rivers).

HABITAT

In freshwater on stones, twigs, and remains of shells. BEHAVIOR

In response to a disturbance, it bends from muscular swellings of the stalks. Fragments of colony with two to three young zooids detach from the colony, drift in water current, or creep on substratum. Eventually, they fix on a favorable habitat and generate a new colony.

FEEDING ECOLOGY AND DIET

Suspension feeder. Feeds on phytoplankton and organic particles.

REPRODUCTIVE BIOLOGY

Buds at basal plate and stalks. Larva trochophorelike. Sexual reproduction is very rare. Calyx often degenerates in low temperature or in any insufficient condition, but regenerates in favorable conditions.

CONSERVATION STATUS

Originally found in the United States. Current worldwide distribution may be due to human activities but the transfer mechanism is still unknown. Not listed by the IUCN.

SIGNIFICANCE TO HUMANS None known. ♦

Loxosomatidae

Solitary entoproct

Loxomitra kefersteinii

ORDER Solitaria

FAMILY Loxosomatidae

TAXONOMY

Loxosoma kefersteinii Claparede, 1867, Naples, Italy.

OTHER COMMON NAMES None known.

PHYSICAL CHARACTERISTICS

Total length up to 0.06 in (1.5 mm). Tentacles number 10-14. Stalk slender, about three times longer than calyx. Bud has tiny attaching organ at base of stalk, but adult loses it and fixes onto substratum.

DISTRIBUTION

South Wales, Great Britain; Naples, Italy; Red Sea; Florida, United States.

HABITAT

Solitary species. Lives on substrata such as body surface of other animals, settlement panels, and water pipes.

BEHAVIOR

In response to a disturbance, it bends along slender, flexible stalk. Newly liberated bud lays its body horizontally and crawls on substratum, twisting the whole body in search of a favorable point to attach to.

FEEDING ECOLOGY AND DIET

Suspension feeder. Feeds on phytoplankton and organic particles.

REPRODUCTIVE BIOLOGY

Budding occurs at latero-frontal areas of calyx. Up to 12 buds on a single animal. Sexual reproduction has not been observed.

CONSERVATION STATUS Not listed by the IUCN.

SIGNIFICANCE TO HUMANS None known. ♦

Resources Books

Hyman, L. H. The Invertebrates: Acanthocephala, Aschelminthes, and Entoprocta. Vol. 3, The Pseudocoelomate Bilateria. New York: McGraw-Hill, 1951.

Nielsen, C. "Entoprocts." In Synopses of the British Fauna (New Series) 41, edited by Doris M. Kermack and R. S. K. Barnes. Leiden, The Netherlands: E. J. Brill., 1989.

Periodicals

Wasson, K. "A Review of the Invertebrate Phylum Kamptozoa (Entoprocta) and Synopses of Kamptozoan Diversity in Australia and New Zealand." Transactions of the Royal Society of South Australia 12ó (2QQ2): 1-2Q.

Tohru Iseto, PhD

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