Invasion History

First Non-native North American Tidal Record: 1953
First Non-native West Coast Tidal Record: 1953
First Non-native East/Gulf Coast Tidal Record:

General Invasion History:

Eusarsiella zostericola is native to the East Coast of North America, where it extends from Nova Scotia to Texas. It has been introduced to San Francisco Bay, California (CA); Humboldt Bay, CA; and Willapa Bay, Washington (WA) (Kornicker 1975; Cohen et al. 2001; California Department of Fish and Wildlife 2014); as well as, several British estuaries on the English Channel (Kornicker 1975; Bamber 1987) and in the Netherlands (Faasse 2013). The likeliest vector for introduction in each of the above instances are transplants of Eastern Oysters (Crassostrea virgnica), from East Coast estuaries to the West Coast and Europe, in the late 19th and early 20th centuries (Kornicker 1975). The small size of these ostracods (1.0-1.5 mm) has probably contributed to their late discovery. Benthic ostracods have limited swimming ability and are rare in ballast water samples (e.g., Carlton and Geller 1993).

North American Invasion History:

Invasion History on the West Coast:

Eusarsiella zostericola was first collected off Point Richmond, San Francisco Bay, CA in 1953, and was initially identified as a new species, Sarsia tricostata. The San Francisco Bay specimens were later found to be conspecific with the East Coast E. zostericola (Kornicker 1967; Kornicker 1975). It is widespread and common to abundant in the South, Central, and San Pablo Bays (Foss 2009; Peterson and Vaysierres 2010) but rare in the Delta (Light et al. 2005). As noted above, it was probably introduced with Eastern Oysters in the late 19th century (Kornicker 1975). In 1999 and 2000, it was collected in Willapa Bay, Washington (Wilson and Partridge 2007; Cohen et al. 2001). In 2011, four specimens were collected in Humboldt Bay, CA (California Department of Fish and Wildlife 2014). Both bays were sites of historical Eastern Oyster transplants.

Invasion History Elsewhere in the World:

Eusarsiella zostericola was collected in England at the Blackwater River estuary in 1967 (Kornicker 1975). It was later collected from Kingsnorth Power Station, on the River Medway, in 1980 (Bamber 1987). In 2012, it was found in the Thames Estuary and west to the Isle of Wight (D.J. Horne, personal communication, cited by Faasse 2013). In 2012, this ostracod was collected in the Oosterschelde estuary, in the Netherlands. Local culture and transplants of mussels and oyster are likely vectors for the transport of E. zostericola (Faasse 2013).


The body of an ostracod is enclosed by a bivalve carapace, with two calcified lateral shells connected by a dorsal band of un-calcified cuticle. The shell can be closed by bundles of transverse muscle fibers (central adductor muscles) near the center of each valve, or opened to permit the appendages to extend for crawling or feeding. The surface of the shell has numerous openings for pore canals, equipped with chemosensory and tactile sensilla, and may be ornamented with pits, tubercles, and irregular projections.

In the order Myocopida, to which Eusarsiella zostericola belongs, notches in the anterior margin of the valves permit the antennae to protrude. The soft body, inside the carapace, consists of a somewhat rigid head capsule, with a labrum and lip, an indistinct thorax, and an unsegmented (or poorly segmented) trunk. There is a small median naupliar eye, anterior to a pair of compound lateral eyes. There are 7 paired limbs in Eusarsiella. Antenna 1 is uniramous. Antenna 2 is adapted for swimming, has a large muscular protopod, and a long exopod with 9 segments, and a small endopod with 1-3 segments. The body terminates in a large furca, anterior to the anus, and ending in prominent claws. Description based on Barnes 1983 and Cohen et al. 2007.

The sexes of E. zostericola are strongly dimorphic. Females are oval, lacking a rostrum, with a posteroventral process and 3 lateral ribs radiating from a hub forward of the center. The posterior rib terminates in a knob with two small lateral pits. A narrow smooth ridge parallels the valve margin. The valve margins have rows of long hairs. Antenna 1 has a 2nd segment with a spinous dorsal seta, a 3rd segment without a ventral seta, and a 4th segment with 3 ventral seta. The endopodite of Antenna 2 of the female has a single joint with 2 proximal seta and a short terminal spine. The female 7th limb has 6 terminal setae and 4-6 proximal setae. The furca does not have secondary claws between the primary claws. Adult females range between 1.1 and 1.6 mm in size, while adult males range between 1.1 and 1.3 mm. Males have a more elongated body, somewhat resembling a lemon, in lateral view, with a small rostrum, and a slight posteroventral process. The 7th limb of males is reduced to a stump, but males have a small copulatory limb. Description based on Kornicker 1967, Kornicker 1986, Bamber 1987, and Cohen et al. 2007.


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Arthropoda
Subphylum:   Crustacea
Class:   Ostracoda
Subclass:   Myodocopa
Order:   Myodocopida
Suborder:   Myodocopina
Superfamily:   Sarsielloidea
Family:   Sarsiellidae
Genus:   Eusarsiella
Species:   zostericola


Sarsiella tricostata (Jones, 1958)
Sarsiella zostericola (Cushman, 1906)
Sarsiella americana (Cushman, 1906)

Potentially Misidentified Species



Eusarsiella zostericola has separate sexes and internal fertilization. Its eggs are brooded. Females in Hadley Harbor, Massachusetts had 5-16 eggs. Development is direct. Males and females mature through five instars to maturity (Kornicker 1967; Bamber 1987).

Eusarsiella zostericola has a broad native range and tolerates a wide span of temperatures and salinities, from near-freezing to 33C, and upper mesohaline to upper euhaline salinities. It occurs over a depth range of 0.18-44.5 m. Habitats include unstructured sediments, ranging from silt to fine sand, oyster beds, eelgrass beds, mangroves, and hydroids. This ostracod is thought to be a carnivore, as one reported specimen contained a harpacticoid copepod (Wass 1972; Kornicker 1967; Kornicker 1986).




fishes, invertebrates

Trophic Status:

Deposit Feeder



General HabitatGrass BedNone
General HabitatOyster ReefNone
General HabitatUnstructured BottomNone
General HabitatMangrovesNone
Salinity RangeMesohaline5-18 PSU
Salinity RangePolyhaline18-30 PSU
Salinity RangeEuhaline30-40 PSU
Tidal RangeSubtidalNone
Vertical HabitatEpibenthicNone

Tolerances and Life History Parameters

Minimum Temperature (ºC)3Field, Long Island Sound NY (Kornicker 1986)
Maximum Temperature (ºC)33Field, St. Lucie inlet, FL (Kornicker 1986)
Minimum Salinity (‰)18Banana River, FL (Kornicker 1986)
Maximum Salinity (‰)42Field, Haulover Canal Kornicker 1986)
Minimum Length (mm)1.3Adults (Bamber 1987)
Maximum Length (mm)1.5Adults (Bamber 1987)
Broad Temperature RangeNoneCold temperate-Subtropical
Broad Salinity RangeNoneMesohaline-Euhaline

General Impacts

There are no known ecological and economic impacts of Eusarsiella zostericola.

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
NA-ET2 Bay of Fundy to Cape Cod 0 Native Estab
NA-ET3 Cape Cod to Cape Hatteras 1906 Native Estab
CAR-I Northern Yucatan, Gulf of Mexico, Florida Straits, to Middle Eastern Florida 0 Native Estab
NEP-V Northern California to Mid Channel Islands 1953 Def Estab
NEA-II None 1967 Def Estab
NEP-IV Puget Sound to Northern California 2000 Def Estab
P090 San Francisco Bay 1953 Def Estab
P270 Willapa Bay 2000 Def Estab
P093 _CDA_P093 (San Pablo Bay) 1953 Def Estab
NA-ET1 Gulf of St. Lawrence to Bay of Fundy 0 Native Estab
CAR-VII Cape Hatteras to Mid-East Florida 0 Native Estab
P130 Humboldt Bay 2011 Def Estab
NEA-III None 2012 Def Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude
26642 Foss 2009 2005 2005-08-25 Ferry Terminal Pier Def 37.7945 -122.3917
29344 Kornicker 1975; Carlton 1979 1953 1953-01-01 Point Richmond Def 37.9230 -122.3940
32949 Foss 2009 2005 2005-06-10 Toll Plaza Def 37.8266 -122.3166
33962 California Department of Fish and Wildlife 2014, 2011 2011-06-29 Aquaculture Floats Def 40.8285 -124.1648


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