Cuthona perca

Invasion History

First Non-native North American Tidal Record: 1967
First Non-native West Coast Tidal Record: 1967
First Non-native East/Gulf Coast Tidal Record: 1969

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General Invasion History:

Cuthona perca is often considered native to the tropical Western Atlantic, but a number of scattered global records calls that assumption into question (Ruiz et al. 2000). It was first collected and described in Brazil (Marcus 1958) and is found north through the Caribbean, including Colombia (Marcus 1976) and Jamaica (Edmunds 1964) to Florida (Marcus 1972; Gosliner 1979), South Carolina (Fox and Ruppert 1985), and Chesapeake Bay (Ruiz et al. 2000). In the eastern Atlantic, it has been found in Ghana (Marcus 1977), where it was probably carried in fouling on ships from the Caribbean (Edmunds 1975; Edmunds 1977). It has also been found in the Lagoon of Venice in the Mediterranean (Perrone 1995) and the Black Sea (Martynov et al. 2007). In the Pacific, C. perca is known from California (Carlton 1979; Cohen and Carlton 1995), Hawaii (Gosliner 1979), Japan (Iwasaki 2005; Kashio and Tanaka 2021), and New Zealand (Miller 1977, as C. reflexa). Cuthona perca is potentially transported in fouling and ballast water, and tolerates a wide range of temperature and salinity.

North American Invasion History:

Invasion History on the West Coast:

On the West Coast, Cuthona perca is known only from Lake Merritt, California where it was found in 1967 (Behrens 1991). Lake Merritt is a tidal lagoon in Oakland, on San Francisco Bay. In the lagoon, C. perca feeds on the introduced anemone Diadumene lineata (Carlton 1979; Cohen and Carlton 1995).

Invasion History on the East Coast:

Cuthona perca was first found in Biscayne Bay, near Miami, Florida in 1969 (Marcus 1976). It was later collected in North Inlet, South Carolina where it was associated with the hydroid Pennaria disticha (Fox and Ruppert 1985; Fernando and Kemp 2007). In 1994, it was found on fouling plates at several locations in Norfolk and Lynnhaven, Virginia. It has also been collected at Yorktown, Virginia where it was locally abundant on the introduced anemone Diadumene lineata (Ruiz et al. unpublished data). Its absence in Vogel's (1977) survey indicates that it may be a recent introduction to the Chesapeake.

Invasion History on the Gulf Coast:

In 1975, Joseph L. Simon reported collecting this nudibranch in St. Petersburg, Florida (Gosliner 1979). We have no further records, but presume that it is still established.

Invasion History in Hawaii:

In 1972, Cuthona perca was collected on floating docks in Kaneohe Bay, Oahu, associated with the sea anemone Aiptasia pulchella (Gosliner 1979; Carlton and Eldredge 2009).

Invasion History Elsewhere in the World:

As noted above, Cuthona perca was described from Brazil, near Cananéia (Sao Paulo state), in lagoons adjacent to the Atlantic Ocean (Marcus 1958; Marcus 1977). It was later collected in Santa Marta, Colombia (Marcus 1976) and Jamaica (Edmunds 1964). These records, together with those from Florida, South Carolina and Virginia, are suggestive of native status in the Western Atlantic, but the scattered global records make it difficult to determine its definitive native range. This sea-slug was first collected in the Eastern Atlantic, in Ghana, Africa, in 1975, where it reportedly only occurred on boat hulls (Edmunds 1977). In 1977, a single specimen was found in the Lagoon of Venice, and later identified as C. perca. No further records are known form the Mediterranean (Perrone 1995; Crocetta 2012). However, in 2007, an established population was found in Sevastopol Bay, Ukraine, on the Black Sea: 'intertidal under stones, within old pier'. The animals were feeding on unidentified sea anemones and producing numerous egg masses (Martynov et al. 2007).

In the Pacific, Cuthona perca was reported from Japan in 1993, and is established (Iwasaki 2005; Kahio and Tanaka). It was reported from New Zealand in the 1970’s (Miller 1977, as C. reflexa; Gosliner 1979); however, its identification was questioned by Miller (2004).

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Description

Cuthona perca is a slender nudibranch which tapers posteriorly. The tail of illustrated specimens varies in size, from about 10 to 25% of the body length. The body length ranges from 3 to 15 mm. The head is rounded and widened laterally, with oral tentacles that are about 10% of the body length. The rhinophores are slightly longer, and smooth, located in front of a pair of small black eyes. The cerata (dorsal and lateral projecting structures) are spindle-shaped and can be up to 25% of the body length. They form about 8-10 rows, with up to 16 cerata in clusters on each side, decreasing posteriorly. The penis bears a short stylet. The color of the translucent body is light orange to yellowish or off-white, with scatterings of opaque white and black flecks. The core of each cerata is olive-green to reddish-brown with a white tip. Cuthona perca lays its eggs in a kidney-shaped mass, containing about 100 eggs, fastened to a substrate by a stalk (Marcus 1958). Larvae are planktonic for a few days (Kashio and Tanaka 2021); Description from: Gosliner 1979; Behrens 1991; Martynov et al 2007.

Miller (2004) argued that the genus Cuthona should be restricted only to the original type species of the genus, C. nana. Based on differences of digestive morphology, he argued that the rest of the species of the genus should be moved to the genus Trinchesia, but this name is not yet universally accepted. This name is used by some authors (e.g. Martinov et al. 2007). The Integrated Taxonomic Information System treats both names as valid (ITIS 2014).

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Taxonomy

Ecology

General:

Cuthona perca is a nudibranch known from estuaries and coastal habitats, including brackish waters. Nudibranchs are simultaneous hermaphrodites and copulate reciprocally or unilaterally. Cuthona perca lays its eggs in a gelatinous mass, attached to a hard substrate. Unhatched veligers rotate inside the eggs which is characteristic of planktotrophic veligers (Martynov et al. 2007). In Brazil, eggs hatched in 8 days at 23-25°C.

Cuthona perca has been reported from lagoons, estuaries, and harbors of warm-temperate to tropical regions. Substrates include rocks, piers, floating docks, and boat hulls (Marcus 1958; Carlton 1979; Gosliner 1979; Martynov et al. 2007). This nudibranch has been found on the introduced Striped Anemone (Diadumene lineata) in Merritt Lagoon (Carlton 1979), on the anemone Aiptasia pulchella in Hawaii (Gosliner 1979), on an unidentified anemone in the Black Sea (Martynov et al. 2007), and on the hydroid Pennaria disticha in South Carolina (Fox and Ruppert 1985). Many nudibranchs which feed on cnidarians, ingest the nematocysts (stinging cells) and incorporate them into their cerata as a defensive mechanism (Barnes 1983). This is probably the case in C. perca.

Food:

Sea anemones and hydroids

Trophic Status:

Carnivore

Carn

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Habitats

General Habitat	Marinas & Docks	None
General Habitat	Rocky	None
General Habitat	Vessel Hull	None
Salinity Range	Polyhaline	18-30 PSU
Salinity Range	Euhaline	30-40 PSU
Tidal Range	Subtidal	None
Vertical Habitat	Epibenthic	None

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Life History

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Tolerances and Life History Parameters

Maximum Temperature (ºC)	27	Field temperature, Sevastopol Bay (Martynov et al. 2007). This nudibranch probably occurs at higher temperatures.
Minimum Salinity (‰)	18	Typical Black Sea salinity, but C. perca was found near a river mouth, where the salinity might be lower (Martynov et al. 2007).
Maximum Salinity (‰)	35	Typical Atlantic Ocean salinity
Minimum Length (mm)	5	Minimum size of animals seen laying eggs (Marcus 1958).
Maximum Length (mm)	15	Gosliner 1979; Behrens 1991; Martynov et al 2007).

General Impacts

No ecological or economic impacts have been reported for Cuthona perca.

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References

Agarwal, Robin Gwen 2023 After the algal bloom cleared out of Lake Merritt, the nudibranchs came to party in droves. https://baynature.org/2023/05/30/after-the-algal-bloom-cleared-out-of-lake-merritt-the-nudibranchs-came-to-party-in-droves/



Barnes, Robert D. (1983) Invertebrate Zoology, Saunders, Philadelphia. Pp. 883

Behrens, D.W. (1991) Pacific Coast Nudibranchs, In: (Eds.) . , Monterey, California. Pp. <missing location>

Carlton, James T. (1979) History, biogeography, and ecology of the introduced marine and estuarine invertebrates of the Pacific Coast of North America., Ph.D. dissertation, University of California, Davis. Pp. 1-904

Carlton, James T.; Eldredge, Lucius (2009) Marine bioinvasions of Hawaii: The introduced and cryptogenic marine and estuarine animals and plants of the Hawaiian archipelago., Bishop Museum Bulletin in Cultural and Environmental Studies 4: 1-202

Cohen, Andrew N.; Carlton, James T. (1995) Nonindigenous aquatic species in a United States estuary: a case study of the biological invasions of the San Francisco Bay and Delta, U.S. Fish and Wildlife Service and National Sea Grant College Program (Connecticut Sea Grant), Washington DC, Silver Spring MD.. Pp. <missing location>

Crocetta, Fabio (2012) Marine alien Mollusca in Italy: a critical review and state of the knowledge, Journal of the Marine Biological Association of the United Kingdom 92(6): 1357-1365

Edmunds, Malcolm (1964) Eolid mollusca from Jamaica, with descriptions of two new genera and three new species., Bulletin of Marine Science of the Gulf and Caribbean 14(1): 1-32

Edmunds, Malcolm (1975) An eolid nudibranch feeding on Bryozoa, The Veliger 17(3): 269

Edmunds, Malcolm (1977) Larval development, oceanic currents, and origins of the opisthobranch fauna of Ghana, Journal of Molluscan Studies 43: 301-308

Fernando, Anthony V.; Kemp, Philip S., Jr. (2007) A key to the benthic shell-less opisthobranch gastropods of North Carolina, Journal of the North Carolina Academy of Science 123(4): 233-241

Fox, Richard S.; Ruppert, Edward E. (1985) <missing title>, University of South Carolina Press, Columbia SC. Pp. 329 pp.

Gosliner, Terence December 6, 1994 Other molluscs, email.. <missing URL>



Gosliner, Terence M. (1979) The systematics of the Aeolidacea (Nudibranchia: Mollusca) of the Hawaiian Islands, with descriptions of two new species., Pacific Science 33(1): 37-77

Integrated Taxonomic Information System 2004-13 Integrated Taxonomic Information System. <missing URL>



Iwasaki, Keiji (2006) Assessment and Control of Biological Invasion Risks., Shoukadoh Book Sellers,and IUCN, Kyoto and Gland, Switzerland. Pp. 104-112

Kashio, Sho; Tanaka, Hiroki (2021) Morphological and ecological notes on the nonindigenous nudibranch Trinchesia perca（Marcus,1958）and its distribution in western Japan, Chiribotan 52(1): 30-43

Marcus, Ernest (1958) On western Atlantic opisthobranchiate gastropods, American Museum Novitates 1906: 1-81

Marcus, Eveline D. R. (1972) On some opisthobranchs from Florida, Bulletin of Marine Science 22: 284-308

Marcus, Eveline d.B.R. (1976) Opisthobranchia von Santa Marta, Colombia, Studies on Neotropical Fauna and Environment 11: 119-150

Marcus, Eveline du Bois Reymond (1977) An annotated checklist of the western Atlantic warm water opisthobranchs, Journal of Molluscan Studies Supplement: 1-22

Marcus, Eveline du Bois-Reymond; Hughes, Helen P. (1974) Opisthobranch mollusks from Barbados, Bulletin of Marine Science 24(3): 498-532

Martynov, Alexander V.; Korshunova, Tatiana A.; Grintsov, Vladimir A. (2007) Opisthobranch mollusks of the northern Black Sea I. Short history of studies and the first record of a non-indigenous nudibranch Trinchesia perca (E. R. Marcus 1958) (Nudibranchia: Tergipedidae), Ruthenica 17(1-2): 43-54

McDonald, Gary R. (2007) The Light and Smith Manual: Intertidal Invertebrates from Central California to Oregon, University of California Press, Berkeley CA. Pp. 788-807

Miller, M. C. (1977) Aeolid nudibranchs (Gastropoda: Opisthobranchia) of the family Tergipedidae from New Zealand waters, Biological Journal of the Linnean Society 60: 197-222

Miller, M. C. (2004) An appraisal of the identity of the New Zealand species of the aeolid nudibranch family Tergipedidae (Gastropoda: Opisthobranchia)., Journal of Natural History 38: 1183-1192

Miller, Michael D. 2004-2014 Slug Site. <missing URL>



Nakajima, Kiyonori; Nakano, Hidehiko; Kasugai, Takashi; Kimura, Taeko; Kimura, Shoichi (2023) Marine Mollusks collected at the Port of Nagoya Garden Pier, located at the far end of Ise Bay in Japan, 10: 111-123

Perrone, Antonio S. (1995) [A species of nudibranch of the genus Cuthona Alder & Hancock 1855, new for the Mediterranean: Cuthona perca (Marcus, 1958)(Opisthobranchia: Nudibranchia)., Bollettino Malacologico 31(1-4): 28-36

Rudman, W. B. 1997-2016 Sea Slug Forum. http://www.seaslugforum.net/



Ruiz, G.M.; Fofonoff, P. W.; Carlton, J. T.; Wonham, M. J.; Hines, A. H. (2000) Invasion of coastal marine communities in North America: Apparent patterns, processes, and biases., Annual Review of Ecology and Systematics 31: 481-531

Ruiz, Gregory M.; Geller, Jonathan (2018) Spatial and temporal analysis of marine invasions in California, Part II: Humboldt Bay, Marina del Re, Port Hueneme, and San Francisco Bay, Smithsonian Environmental Research Center & Moss Landing Laboratories, Edgewater MD, Moss Landing CA. Pp. <missing location>

Vogel, Rosalie M. (1977) <missing title>, M.S. Thesis, College of William and Mary, Williamsburg, VA.. Pp. <missing location>

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