Common name: Black Sea jellyfish
available through www.itis.gov
Size: polys - 1-2mm; medusae 10 mm (Mills and Sommer 1995).
Native Range: Black Sea (Mills and Sommer 1995).
Hydrologic Unit Codes (HUCs) Explained
Puerto Rico &
Interactive maps: Point Distribution Maps
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 Blackfordia virginica are found here.
Table last updated 5/25/2018
† Populations may not be currently present.
Means of Introduction: One researcher has concluded, based on genetics, this species is native to the Black Sea and was likely transported to the East Coast of North America prio to 1910 in ship ballast water (Thiel 1935; Mills and Sommer 1995). Specimens deposited at the California Academy of Sciences reveal this species was collected in the early 1970s in the Bay area, but was misidentified as Phialidium sp. One collection was of 150 to 200 individuals from the Napa River in September 1970. A second contained eight individuals from the Petaluma River in September 1974. Therefore, it is likely that this species has been in the San Francisco Bay area and has gone undetected for over 20 years (Mills and Sommer 1995).
Status: Established in California. Reported from Virginia.
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)
Carlton, J.T. 1985. Transoceanic and interoceanic dispersal of coastal marine organisms: The biology of ballast water. Oceanogr. Mar. Biol. Ann. Ref. 23:313-371.
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.
Theil, M.E. 1935. Zur Kenntnis der Hydromedusenfauna des Schwarzen Meeres. Aool. Anz 111:161-174.
Revision Date: 4/3/2006
Fuller, P., 2018, Blackfordia virginica Mayer, 1910: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=1050, Revision Date: 4/3/2006, Access Date: 10/22/2018
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.