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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: freshwater goblet worm

Taxonomy: available through www.itis.gov

Identification: Urnatella gracilis is a freshwater colonial Entoproct (small sessile aquatic animal) that grows in a single stalk or in groups of up to six stalks (zooids) connected at the base by a stolon (basal plate) (Davenport 1893, Dana et al. 1854). The stalks are segmented with upwards of 16-18 segments, and can have curved, semi-erect branches that attach at the base by the lowest segment (Dana et al. 1854). The top segment, or active polyp (calyx) is bell-shaped, and the rim is lined with 12-14 cylindrical, ciliated tentacles that encircle the upward-facing mouth (Dana 1854, Davenport 1893). Segments are translucent and white to yellow in color and segments narrow in size as they approach the calyx (Dana et al. 1854, Davenport 1893).

Urnatella gracilis is the only freshwater kamptozon in North America. There is only one other known species of freshwater Entoproct, Loxosomatoides sirindhornae, which is native to Thailand (Wood et al. 2006).

Size: From 500 µm up to 3 mm in height (McCullough and Smith 1975).

Native Range: Native to freshwaters of the northeastern United States in Pennsylvania, Illinois, Michigan, Indiana, Virginia, Tennessee, Kentucky, Ohio and in Lake Erie (Edmondson 1959, McCullough and Smith 1975), the Trinity River basin in Lake Dallas, Texas and in Oklahoma (Weise 1961).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology: Urnatella gracilis is the only species of freshwater Entoproct native to North America and can be found in lakes and rivers growing as a single stock or in colonies on twigs, bark, stones, and mussel shells (McCullough and Smith 1975, Pennak 1953, Weise 1961). This species is somewhat salt tolerant and can withstand brackish water and moderate pollution, sometimes being found in waters with high nitrogen, phosphate, chloride, and ammonia levels (McCullough and Smith 1975, Weise 1961). It is a suspension feeder and passively feeds on phytoplankton and algae, using ciliated tentacles to capture food and move it toward the mouth (McCullough and Smith 1975, Weise 1961).

Urnatella gracilis reproduces both sexually and asexually. During asexual reproduction, new stocks are formed via budding, which occur either as a linear series of segments (or a “branch”) off the main stock, or where a calyx arises from a single-segmented stock at the stolen (basal plate) (Dana et al. 1854). It is thought that U. gracilis is a protandrous hermaphrodite (meaning it changes sex from male to female during growth but does not have male and female gonads simultaneously) (Nielsen 1983). During sexual reproduction, spermatozoa are expelled into the water column and fertilize eggs in the ovary of the adult, eventually developing into planktonic larvae that are then capable of producing new colonies (Nielsen 1983).

Means of Introduction: Most nonindigenous occurrences of Urnatella gracilis are likely attributed to ballast water discharge from ships (Hamelin et al. 2016). The occurrence in the lower Snake River, WA was likely due to hitch-hiking on fishing or boating equipment.

Status: Urnatella gracilis is established in California, USA in the lower Sacramento and San Joaquin Delta drainages. It was also collected in the Lower Snake River in Washington, USA in 2006. It is established in the St. Lawerence River in Becancour, Quebec, and in the Black Sea and the Sea of Azov in eastern Europe.

Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.

References: (click for full references)

Dana, J.D., A.L. Heermann, J. Le Conte, J. Leidy, and E. Hallowell. 1854. On Urnatella gracilis and a New Species of Plumatella. Proceedings of the Academy of Natural Sciences of Philadelphia, pp.175-194.

Davenport C.B. 1893. On Urnatella gracilis. Bulletin of the Museum of Comparative Zoology, Harvard 24, 1–44.

Edmondson, W.T. 1959. Fresh-water biology. John Wiley, New York. 1248 pp.

Gomoiu, M.T., B. Alexandrov, N. Shadrin, and Y. Zaitsev. 2002. The Black Sea: a recipient, donor and transit area for alien species. In Invasive aquatic species of Europe. Distribution, impacts and management. Dordrecht: Springer Netherlands. 341-350 pp.

Hull, H.C., L.F. Bartos, and R.A. Martz. 1980. Occurrence of Urnatella gracilis Ledidy in the Tampa Bay Bypass Canal, Florida . Florida Scientist, 43(1):12–14. http://www.jstor.org/stable/24319728

Hamelin, K.M., R.A. Castañeda, and A. Ricciardi. 2016. Cryptic invaders: nonindigenous and cryptogenic freshwater Bryozoa and Entoprocta in the St. Lawrence River. Biological Invasions 18: 1737–1744. https://doi.org/10.1007/s10530-016-1116-3

McCullough, J.D., and B. Smith. 1975. Some ecological observations on Urnatella gracilis Leidy., Southwestern Naturalist 20(2): 171-176.

Nielsen, C., 1983. Entoprocts: Keys and notes for the identification of the species (Vol. 41). Brill Archive.

Pennak, R.W. 1953. Fresh-water invertebrates of the United States. McGraw-Hill, New York. 769 pp.

Weise, J.G. 1961. The ecology of Urnatella gracilis Leidy: Phylum Endoprocta. Limnology and Oceanography. 6:228-23.

Wood, T.S., P. Anurakpongsatorn, and J. Mahujchariyawong. 2006. Freshwater bryozoans of Thailand (Ectoprocta and Entoprocta), Natural History Journal of Chulalongkorn University 6(2): 83-119.

Author: Reaver, K.M.

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.