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.

Cordylophora caspia
Cordylophora caspia
(freshwater hydroid)

Copyright Info
Cordylophora caspia Pallas, 1771

Common name: freshwater hydroid

Taxonomy: available through www.itis.govITIS logo

Identification: This colonial hydroid consists of macroscopic polyps (about 1 mm) connected by a gastrovascular cavity; branching, moss-like in appearance (Pennak, 1987). Colonies grow up to 5 cm, which varies depending on conditions (Folino 2000).

Size: Colonies to 5 cm, polyps around 1 mm.

Native Range: Black and Caspian seas of western Asia.

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

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Cordylophora caspia are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
AZ201520152Havasu-Mohave Lakes; Lower Lake Powell
CA193020108Lower Sacramento; Mad-Redwood; Middle San Joaquin-Lower Chowchilla; Monterey Bay; San Francisco Bay; San Francisco Coastal South; San Joaquin Delta; San Pablo Bay
IL199920072Lake Michigan; Lower Illinois-Lake Chautauqua
MD200020001Upper Chesapeake Bay
MA200020001Ashuelot River-Connecticut River
MN200120011Lake Superior
MO201320131Lake of the Ozarks
NV201420151Lake Mead
NY199620072Lower Hudson; Seneca
OR200020032Coos; Lower Columbia
WA1920200610Duwamish; Lake Washington; Lower Columbia; Lower Snake; Lower Snake-Tucannon; Puget Sound; Queets-Quinault; Strait of Georgia; Walla Walla; Willapa Bay
WI201720181St. Louis

Table last updated 6/18/2024

† Populations may not be currently present.

Ecology: Cordylophora caspia is a colonial hydroid that lives in freshwater and brackish habitats. Colonies are composed of three types of chitin tubes: stolons, uprights, and branches (Seyer et al., 2017). C. caspia can reproduce sexually or asexually via fragmentation (Pucherelli et al., 2016). During sexual reproduction, ova are retained in female gonophores. Male gonophores release sperm that fertilize the eggs in female gonophores. Female gonophores then release planula larvae to find suitable substrate; these larvae grow into new colonies of C. caspia (Seyer et al., 2017; Pucherelli et al., 2016). Unlike other cnidarians, C. caspia does not have a medusoid stage (Pucherelli et al., 2016). C. caspia colonies can respond to adverse conditions by producing a resting stage called a menont that remains sheltered within the hydrocaulus; these menonts can regenerate colonies when favorable conditions return (Seyer et al., 2017).

C. caspia has relatively broad environmental tolerances. They can survive temperatures ranging from 8 to 30 degrees celsius and salinity as high as 40 ppt (Seyer et al., 2017). Colonies of C. caspia grow on hard substrates such as rock surfaces, shells, wood, and submerged infrastructure (Pucherelli et al., 2016).

This species is considered a benthic predator, capturing prey using nematocysts: their diet includes small crustaceans, worms, insect larvae, watermites and other zooplankton and benthic invertebrates (Pucherelli et al., 2016). Their diet puts them in competition with many species of larval, juvenile, and benthivorous fish (Seyer et al., 2017). They also compete with other benthic species for substrate; however, their filamentous structure may also provide substrate for chironomids, caddisflies and Dreissena spp. veligers (Folino-Rorem, 2015).

Means of Introduction: Possibly introduced by aquarium release (Mills et al., 1993), or through ballast water exchange (Seyer et al., 2017)

Status: Established in Lake Erie (U.S. EPA 2008)

Impact of Introduction: Smith et al. (2002) described C. caspia as a 'benthic colonial predator' that preys upon chironomids and other larval insects. This may result in less prey availability for fish. The ecological impacts of C. caspia, however, have not yet been thoroughly studied. Uncolonized substrate introduced to C. caspia and subsequently colonizied had different realtive abundances of other invertebrates as compared to substrates not colonized by C. caspia (Ruiz et al. 1999). Other studies have suggested that C. caspia may contribute to a restructuring of benthic and pelagic freshwater communities (Folino 2000).

Competition for space, i.e. suitable substrate for colonization, may occur between zebra mussel (Dreissena polymorpha) and C. caspia (Walton 1996, Folino 2000). Cordylophora caspia also typically eats zebra and quagga mussel larvae.

There is a negative economic impact associated with the biofouling caused by Cordylophora caspia (Folino 2000).

Remarks: Smith et al. (2002) noted that C. caspia shows morphological and ecological changes in habitats of lower salinity such as inland freshwaters. For example, growth rates decrease, reproductive rates decrease (sexually and asexually), polyp size changes, population density changes, and cell size and shape is altered (Smith et al. 2002 and references).

Cordylophora caspia is preyed upon by an introduced nudibranch (Tenellia adspersa) (Mills and Sommer 1995).

Cordylophora caspia is thought to be taxonomically synonymous with C. lacustris by many scientific researchers (Folino 2000 and references).

References: (click for full references)

Anderson, R.C. 1995. Nudibranchs: butterflies of the sea. International Zoo Yearbook 34.1: 65-70. Web.

Berg, M.B., and N.C. Folino-Rorem. 2009. Alterations of Lake Michigan benthic communities by the invasive colonial hydroid, Cordylophora caspia: effects on fish prey. Unpublished report. Available: http://www.iisgcp.org/research/ais/Berg_Rorem_Final_Report.pdf

Carlton, J.T., and M.H. Ruckelshaus. 1997. Nonindigenous marine invertebrates and algae. Pages 187-201 In: Simberloff, D., D.C. Schmitz, T.C. Brown (eds), Strangers in Paradise. Island Press, Washington, D.C.

Darling, J.A., and N.C. Forino-Rorem. 2009. Genetic analysis across different spatial scales reveals multiple dispersal mechanisms for the invasive hydrozoan Cordylophora in the Great Lakes. Molecular Ecology 18:4827-4840.

Folino, N.C. 2000. The freshwater expansion and classification of the colonial hydroid Cordylophora (Phylum Cnidaria, Class Hydrozoa). In Pederson, J. (ed.) Marine Bioinvasions: Proceedings of the First National Conference, January 24-27, 1999. Massachusetts Institute of Technology Sea Grant College Program, Cambridge, MA. pp. 139-144.

Gutierre, S.M. 2012. pH tolerance of the biofouling invasive hydrozoan Cordylophora caspia. Hydrobiologia 671: 91-95.

Mant, R. C., G. Moggridge, and D. C. Aldridge. 2011. Biofouling by Bryozoans, Cordylophora, and Sponges in UK Water Treatment Works. Water Science and Technology 63.9: 1815-822. Web.

Mills, C.E., and F. Sommer. 1995. Invertebrate introductions in marine habitats: two species of hydromedusae (Cnidaria) native to the Black Sea, Maeotias inexspectata and Blackfordia virginica, invade San Francisco Bay. Marine Biology 122:279-288.

Mills, E.L., M.D. Scheuerll, D.L. Strayer, and J.T. Carlton. 1996. Exotic species in the Hudson River basin: a history of invasions and introductions. Estuaries 19(4):814-823.

Mills, E.L., J.H. Leach, J.T. Carlton, and C.L. Secor. 1993. Exotic species in the Great Lakes: a history of biotic crises and anthropogenic introductions. Journal of Great Lakes Research 19(1):1-54.

Moreteau, J.C., and M. Khalanski. 1994. Settlings and growth of D. polymorpha in the raw water circuits of the Cattenom Nuclear Power Plant (Moselle, France). Proceedings of the Fourth International Zebra Mussel Conference, Madison, WI, March 1994. pp. 553-574.

Pennak, R.W. 1987. Coelenterata (Hydroids, Jellyfish). Pages 110-123 in Fresh-water Invertebrates of the United States, 3rd edition. John Wiley and Sons, Inc., New York. 628 p.

Portella, K.F., and A. Joukoski. 2009. Biofouling and chemical biodeterioration in hydroelectric power plant Portland cement mortar. Química Nova 32(4):1047-1051.

Ringelband, U., and L. Karbe. 1996. Effects of Vanadium on Population Growth and Na-K-ATPase Activity of the Brackish Water Hydroid Cordylophora caspia. Bulletin of Environmental Contamination and Toxicology 57.1: 118-24. Web.

Ruiz, G.M., and A.H. Hines. 1997. The risk of nonindigenous species invasion in Prince William Sound associated with oil tanker traffic and ballast water management: pilot study. Prepared for the Regional Citizens' Advisory Council of Prince William Sound.

Ruiz, G.M., P. Fofonoff, and A.H. Hines. 1999. Non-indigenous species as stressors in estuarine and marine communities: assessing invasion impacts and interactions. Limnology and Oceanography 44(3, part 2):950-972.

Smith, D.G., S.F. Werle, and E. Klekowski. 2002. The rapid colonization and emerging biology of Cordylophora caspia (Pallas, 1771) (Cnidaria: Clavidae) in the Connecticut River. Journal of Freshwater Ecology 17(3):423-430.

U.S. Environmental Protection Agency (USEPA). 2008. Predicting future introductions of nonindigenous species to the Great Lakes. National Center for Environmental Assessment, Washington, DC; EPA/600/R-08/066F. Available from the National Technical Information Service, Springfield, VA, and http://www.epa.gov/ncea.

Walton, W.C. 1996. Occurrence of zebra mussel (Dreissena polymorpha) in the oligohaline Hudson River, New York. Estuaries 19(3):612-618.

Wurtz, C.B., and S.S. Roback. 1955. The invertebrate fauna of some Gulf Coast rivers.  Proceedings of the Natural Sciences Academy of Philadelphia 107:167-206.

Author: Fuller, P., E. Maynard, D. Raikow, J. Larson, T.H. Makled, and A. Fusaro

Revision Date: 9/12/2019

Citation Information:
Fuller, P., E. Maynard, D. Raikow, J. Larson, T.H. Makled, and A. Fusaro, 2024, Cordylophora caspia Pallas, 1771: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=1060, Revision Date: 9/12/2019, Access Date: 6/18/2024

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.


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Citation information: U.S. Geological Survey. [2024]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [6/18/2024].

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