Invasion History

First Non-native North American Tidal Record: 1983
First Non-native West Coast Tidal Record:
First Non-native East/Gulf Coast Tidal Record: 1983

General Invasion History:

Stiliger fuscovittatus is native to the Pacific Coast of North America from the Gulf of California, Mexico to Ketchikan, Alaska, both on exposed coasts and in estuaries. It has been collected twice in the Indian River Lagoon, Florida, and at least once at an unspecified location in Texas (Jensen and Clark 1983; Clark 1995; Trowbridge 2002; Behrens 2006, in Rudman 2009). These were most likely ballast water introductions, but no established populations are known in the Atlantic.

North American Invasion History:

Invasion History on the East Coast:

Stiliger fuscovittatus was collected in 1983 in Titusville, Florida, in the Indian River Lagoon, on algae attached to a marker float (Jensen and Clark 1983), and later at Sebastian Inlet (Clark and de Freese 1987, cited by Clark 1995; Mikkelsen at al. 1995). Both collections were single animals. Behrens (in Rudman 2006) refers to a record from Texas, but we have not found the specific location. Stiliger fuscovittatus may have been transported through the Panama Canal in ballast water, but has not become established on the Gulf or Atlantic coasts, to our knowledge.


Stiliger fuscovittatus has a long and slender body, with what appears to be smooth, pointed oral tentacles. It actually lacks oral tentacles, but has long, simple rhinophores. The cerata begin about 1/4 of a body length behind the rhinophores. The cerata are long and club-shaped, and are deciduous – they can be jettisoned with stress or rough handling. The animal reaches 15 mm in length. The body is white to grayish white, with irregular reddish-brown streaks and lines, and two parallel streaks running from the rhinophores along the body. The food in the digestive system shows through the body wall, aiding in camouflage. Description based on Behrens (1991), Behrens (in Rudmam 2006), and McDonald (2007).

There appears to be considerable disagreement as to whether this opisthobranch belongs in the genera Stiliger (Lance 1962, cited by Behrens 1991; Trowbridge 2006, in Rudman 2006) or Ercolania (Jensen, in Rudman 2006; Rosenberg 2014), resulting in a gender shift in the species name.


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Mollusca
Class:   Gastropoda
Subclass:   Opisthobranchia
Order:   Sacoglossa
Family:   Stiligeridae
Genus:   Stiliger
Species:   fuscovittatus


Ercolania fuscovittatus (Lance, 1962)

Potentially Misidentified Species

Ercolania fuscata
(Synonym Stiliger fuscata) Northwest Atlantic native from New Hampshire to Florida (Rosenberg 2014)

Tenellia adspersa
Tenellia spp. are in the order Nudibranchia, but superficially resemble Stiliger, and feed on hydroids. Tenellia spp. have oral tentacles, lacking in Stiliger. Tenellia spp. can have one or two pairs of cerata in each row, while Stiliger has only a single pair in each row.Tenellia adpersa is cryptogenic on the East Coast, but introduced on the West Coast. Tenellia fuscata and T. adspersa are frequently confused.

Tenellia fuscata
Tenellia spp. are in the order Nudibranchia, but superficially resemble Stiliger, and feed on hydroids. Tenellia spp. have oral tentacles, which are lacking in Stiliger. Tenellia spp. can have one or two pairs of cerata in each row, while Stiliger has only a single pair in each row.Tenellia fuscata is native to the East Coast. Tenellia fuscata and T. adspersa are frequently confused.



Stiliger fuscovittatus is a small herbivorous sacoglossan sea-slug, found on algae on rocky shores and estuaries. The animals are hermaphroditic and apparently do not self-fertilize. Fertilization is internal, and the individual lays egg masses containing up to 232 eggs per day, attached to the algae on which the animals feed. Individuals, as small as 3 mm, can lay eggs. The eggs hatch into veligers, which lack yolk, and so are most likely planktotrophic (Case 1972, cited by Trowbridge 2002).

Stiliger fuscovittatus appears to have a broad temperature tolerance, based on its range and on experiments. It also tolerates considerable salinity variation (Case 1972, cited by Trowbridge 2002; Trowbridge 2002). It occurs and feeds on red algae of the genera Polysiphonia, Callithamnion, and Dasya. It feeds on epiphytic forms of these algal genera (growing on other algae), and those directly attached to a non-algal substrate (Trowbridge 2002; Trowbridge, in Rudman 2006).


Red algae (Polysiphonia spp.)

Trophic Status:




General HabitatMarinas & DocksNone
General HabitatRockyNone
General HabitatUnstructured BottomNone
Salinity RangePolyhaline18-30 PSU
Salinity RangeEuhaline30-40 PSU
Tidal RangeSubtidalNone
Tidal RangeLow IntertidalNone
Vertical HabitatEpibenthicNone

Tolerances and Life History Parameters

Minimum Temperature (ºC)4Experimental (Case 1972, cited by Trowbridge 2002)
Maximum Temperature (ºC)23Experimental (Case 1972, cited by Trowbridge 2002)
Minimum Salinity (‰)21Experimental- Survival was ~100% at 21 PSU for 72 hours, but 50% at 13 PSU (Case 1972, cited by Trowbridge 2002).
Maximum Salinity (‰)33Experimental- Highest tested (Case 1972, cited by Trowbridge 2002).
Minimum Length (mm)3Individuals as small as 3 mm can lay eggs (Case 1972, cited by Trowbridge 2002)
Maximum Length (mm)15Behrens 1991
Broad Temperature RangeNoneCold temperate-tropical
Broad Salinity RangeNonePolyhaline-Euhaline

General Impacts

Stiliger fuscovittatus is an abundant grazer of red algae on the West Coast, but despite being introduced to the East and Gulf coasts, it has not become established and has had no reported impacts.

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
NEP-IV Puget Sound to Northern California 0 Native Estab
NEP-V Northern California to Mid Channel Islands 0 Native Estab
NEP-VI Pt. Conception to Southern Baja California 0 Native Estab
NEP-VII None 0 Native Estab
CAR-I Northern Yucatan, Gulf of Mexico, Florida Straits, to Middle Eastern Florida 1983 Def Unk
S190 Indian River 1983 Def Failed
NEP-III Alaskan panhandle to N. of Puget Sound 0 Native Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude


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

Carlton, James T. (Ed.) (2007) <missing title>, University of California Press, Berkeley. Pp. <missing location>

Clark, Kerry B. (1995) Rheophilic/oligotrophic lagoonal communities through the eyes of slugs (Mollusca: Opisthobranchia), Bulletin of Marine Science 57(1): 242-251

Goddard, Jeffrey H. R. (2001) An identification guide to larval marine invertebrates of the Pacific Northwest, Oregon State University Press, Corvallis OR. Pp. 86-128

Jensen, Kathe; Clark, Kerry B. (1983) Annotated checklist of Florida ascoglossan Opisthobranchia, Nautilus 97(1): 1-13

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

Mikkelsen, Paula M., Mikkelsen, Paul S., Karlen, David J. (1995) Molluscan biodiversity in the Indian River Lagoon, Florida, Bulletin of Marine Science 57(1): 94-127

Millen, S.V. (1989) Opisthobranch range extensions in Alaska with the first records of Cuthona viridis (Forbes, 1840) from the Pacific, The Veliger 32: 64-68

Rosenberg, Gary 1995-2015 Malacolog.

Rudman, W. B. 1997-2016 Sea Slug Forum.

Trowbridge, Cynthia D. (2002) Northeast Pacific saccoglossan opishtobranchs: Natural history review, biology, and prospectus, Veliger 45(1): 1-24