Invasion History

First Non-native North American Tidal Record: 2000
First Non-native West Coast Tidal Record:
First Non-native East/Gulf Coast Tidal Record: 2000

General Invasion History:

Penilia avirostris is widely distributed in coastal regions around the world, including tropical, subtropical, and warm-temperate regions. It was described from Brazil by Dana in 1849, but its native range is difficult to discern. It was collected on both sides of the Atlantic, the Mediterranean and Black Seas, the Indian Ocean, and the western Pacific by 1933 (Ramner 1933, cited by Dolgopol'skya 1959). This species shows little geographic genetic structure, supporting the idea that it is a fairly recent colonizer of the world's oceans, perhaps in the Pleistocene or Holocene (Durbin et al. 2008). It is adapted to marine environments, and cannot survive in freshwater (Aladin 1981).

In the temperate Northwest Atlantic, P. avirostris was studied in Beaufort, North Carolina in the 1890s (Sudler 1898, cited by Colton 1985), which was its apparent northern limit. In the 20th century, it was collected progressively northward, Delaware Bay in 1931, Block Island Sound and Woods Hole in 1943, and Nantucket Shoals in 1981 (Lochhead 1954; Colton 1985). In 1981, isolated patches occurred on Georges Bank. This range extension appears related to increased water temperatures, but run counter to prevailing currents. Colton (1985) suggested transport of resting eggs by birds, or in the cooling systems of fishing boats as possible vectors. Recent evidence suggests that it is introduced on Prince Edward Island, Gulf of St. Lawrence, Canada (Bernier and Locke 2006).

North American Invasion History:

Invasion History on the West Coast:

Penilia avirostris has been found in ballast water of ships docked in Puget Sound, where this species is absent in the estuary (Cordell et al. 2009; Cordell and Kalata 2015). A collection of a few specimens in the Bering Sea (Onbe et al. 1996) is probably due to dispersal by warm currents from the coast of Asia to the south.

Invasion History on the East Coast:

While natural northward range extensions in the Northeastern and Northwestern Atlantic could involve currents, a localized occurrence of P. avirostris in Colville Bay, Prince Edward Island (Gulf of St. Lawrence, 46°N, 52°W) in 2000, is likely a ballast introduction (Bernier and Locke 2006). This cladoceran was found in increased densities in 2001 (up to 27.5 m-3), with juveniles and males present, indicating that population was producing resting eggs. This population is 5 degrees north of the nearest previous occurrence. The nearby port of Souris receives local boat traffic, but little international shipping. Ballast water from ships entering the St. Lawrence Seaway is a possible source (Bernier and Locke 2006).

Invasion History Elsewhere in the World:

Penilia avirostris has been caught sporadically in the Caspian Sea since 1985, but the establishment of populations is unknown (Aladin 2002, Shiganova et al. 2005; Shiganova 2010). These animals were probably introduced in the ballast water of ships coming from the Black Sea by the Volga-Don Canal.


Penilia avirostris is the only fully marine filter-feeding cladoceran. The other seven species of marine cladocerans belong to the family Podonidae, and are distinguished by a single large eye, closed carapace, and claw-like, raptorial appendages. In contrast, P. avirostris has a bivalve carapace, open ventrally, a small compound eye, and six pairs of feathery, filter-feeding appendages. The carapace is roughly oval, with ventral posterior edges prolonged into triangular spines. The ventral edges of the carapace are lined with fine spines. The head is distinct, with a downward-pointing rostrum, resembling a bird's beak (whence the species name). The abdomen bends sharply, ventrally, at the end of the carapace, and ends in two long spines. The antennule is weakly developed in the female. The antenna is biramous, and is as long as the carapace. Adult parthenogenetic females have a dorsal brood chamber, which contains developing embryos (Johnson and Allen 2005). Fertilized females produce a pair of large, oval resting eggs. Females range from 0.4 to 1.2 mm in body length. Description based on: Dolgopol'skya 1959; and Johnson and Allen 2005.

Females reproduce parthenogenetically, through much of the season, so males are usually rare. The male is distinguished by its lack of a rostrum; its long antennules, which are nearly as long as the carapace; curved hook-like setae on the first pair of thoracic legs; and two long penises, at the posterior end of the body. Males are 0.7-0.9 mm in length. Description based on Dolgopol'skya 1959; Egloff et al. 1997; and Johnson and Allen 2005.


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Arthropoda
Subphylum:   Crustacea
Class:   Branchiopoda
Superorder:   Diplostraca
Order:   Cladocera
Infraorder:   Ctenopoda
Family:   Sididae
Genus:   Penilia
Species:   avirostris


Potentially Misidentified Species



Penilia avirostris is the only filter-feeding marine cladoceran. During most of its annual cycle, the whole population is female. Newborn females develop a dorsal brood-pouch, in which eggs are deposited. Unlike most freshwater species, the brood-pouch is closed, and nutrients are provided to the young through a placenta-like arrangement. The number of embryos varies with body size and environmental conditions, from 1-17 embryos. Development time varies with temperature and food supply, but was about 2-3 days at 21-25 C (Paffenhofer and Orcutt 1986, cited by Egloff et al. 1997; Miyashita et al. 2010). Release of embryos occurs throughout the diel cycle, but is more frequent at night (Wong et al. 2008). Young females are born at about 0.320-450 mm (Atienza et al. 2008; Egloff et al. 1997), and grow for 2-3 days before eggs are deposited in the brood pouch.

In temperate regions, the cycle of occurrence of P. avirostris is strongly seasonal, August-October in Prince Edward Island (Bernier and Locke 2006), July-October in Narragansett Bay (Fofonoff 1994), and July-December in Spain (Atienza et al. 2008; Piontkovski et al. 2012). In tropical regions, this species can occur year-round (Miyashita et al. 2010; Piontkovski et al. 2012). In temperate regions, males tend to appear near the declining end of the population cycle (Egloff et al. 1997; Atienza et al. 2008), while in tropical regions, they may occur year-round (Miyashita et al. 2010). Fertilized females produce two large, oval, resting eggs, which develop in the brood pouch. When the female dies, the eggs fall into the sediment. The eggs may hatch when conditions are suitable. Eggs from sediments in Japan hatched best at salinities above 28 PSU and temperatures above 18 C, although some hatching occurred at 12 C and 19 PSU (Egloff et al. 1997). Abundant populations occur in the Black Sea at 18 PSU and the Red Sea up to 43 PSU (Lochhead 1964).

Penilia avirostris feeds by filtering fine particles in the water column (Egloff et al. 1997). Populations in Spain fed primarily on particles 2- 20 μm, primarily flagellates, but also diatoms and dinoflagellates (Atienza et al. 2006). Populations frequently show a pattern of vertical migration, moving towards the surface at night, and descending by day, to avoid predation (Wong et al. 2008).


Phytoplankton, Bacteria


Fishes, Medusae, Ctenophores


Copepods, salps, larvaceans

Trophic Status:

Suspension Feeder



General HabitatUnstructured BottomNone
Salinity RangePolyhaline18-30 PSU
Salinity RangeEuhaline30-40 PSU
Tidal RangeSubtidalNone
Vertical HabitatPlanktonicNone

Tolerances and Life History Parameters

Minimum Temperature (ºC)-1Penilia avirostris populations persist in embayments where ice forms in winter, by means of resting eggs (Lochhead 1954; Eggloff et al. 1997). Resting eggs hatched at temperatures as low as 12 C, although hatching was optimal above 18 C (Egloff et al. 1997).
Maximum Temperature (ºC)30Bryan and Grant (1979, cited by Egloff et al. 2012)
Minimum Salinity (‰)12Aladin et al. 1981 (Experimental)
Maximum Salinity (‰)49Bitter Lakes, Suez Canal (Lochhead 1954)
Minimum Reproductive Temperature10Field (Colton 1985; Johns et al. 2005; Bernier and Locke 2006)
Maximum Reproductive Temperature30Bryan and Grant (1979, cited by Egloff et al. 2012)
Minimum Reproductive Salinity12Aladin et al. 1981 (Experimental)
Maximum Reproductive Salinity43Red Sea (Lochhead 1954)
Minimum Length (mm)0.4Egg-bearing females (Dolgopol'skya 1959; Johnson and Allen 2005).
Maximum Length (mm)1.2Egg-bearing females (Dolgopol'skya 1959; Johnson and Allen 2005).

General Impacts

Penilia avirostris reaches high abundances (> 1000 m-3) in its native range and in some introduced locations (e.g. North of Cape Hatteras in the Northwest Atlantic) (Colton 1985; Johns et al. 2005), and may play an important role as a grazer of small phytoplankton (2 - 20 μm diameter) (Atienza et al. 2006). However, in the two regions in which it has been definitely introduced, Colville Bay (Prince Edward Island, Bernier and Locke 2006) and the Caspian Sea (Shiganova et al. 2010) abundances are probably too low to have significant impacts.

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
NA-S3 None 2000 Def Estab
CAR-VII Cape Hatteras to Mid-East Florida 1898 Native Estab
NA-ET3 Cape Cod to Cape Hatteras 1931 Crypto Estab
NEA-II None 1947 Crypto Estab
SA-II None 0 Native Estab
WA-II None 0 Native Estab
WA-IV None 0 Native Estab
EA-IV None 0 Native Estab
EA-III None 0 Native Estab
RS-3 None 0 Native Estab
MED-II None 0 Native Estab
MED-III None 0 Native Estab
MED-VII None 0 Native Estab
MED-V None 0 Native Estab
MED-IX None 0 Native Estab
CASP Caspian Sea 1954 Def Unk
CIO-I None 0 Native Estab
CIO-II None 0 Native Estab
EAS-VII None 0 Native Estab
EAS-I None 0 Native Estab
AUS-X None 0 Native Estab
NWP-4a None 0 Native Estab
NWP-4b None 0 Native Estab
NZ-IV None 0 Native Estab
NEP-VI Pt. Conception to Southern Baja California 0 Native Estab
NEA-V None 0 Native Estab
NWP-3a None 0 Native Estab
SA-I None 0 Native Estab
MED-VI None 0 Native Estab
MED-III None 0 Native Estab
MED-IV None 0 Native Estab
CAR-II None 0 Native Estab
AUS-IV None 0 Native Estab
NWP-2 None 0 Native Estab
NWP-3b None 0 Native Estab
CAR-I Northern Yucatan, Gulf of Mexico, Florida Straits, to Middle Eastern Florida 0 Native Estab
NEA-IV None 0 Crypto Estab
MED-VIII None 0 Native Estab
SEP-I None 0 Native Estab
B-I None 1997 Crypto Estab
NEA-III None 0 Crypto Estab
NEP-II Alaska south of the Aleutians to the Alaskan panhandle 1989 Native Unk

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude


Aladin, N. V. (1981) [Salinity adaptations and osmoregulatory abilities of cladoceran crustaceans: 1. Forms of the open ses and oceans], Zoologichaeskii Zhurrnal 61: 341-352

Aladin, Nikolai V.; Plotnikov, Igor S.; Filipov, Andrei A. (2002) Invasive aquatic species of Europe: Distribution, impacts, and management., Kluwer Academic Publishers, Dordrecht. Pp. 351-359

Appeltans, W. et al. 2011-2015 World Registry of Marine Species. <missing URL>

Atienza, D.; Saiz, E.; Skovgaard, A.; Trepat, I.; Calbet, A. (2008) Life history and population dynamics of the marine cladoceran Penilia avirostris (Branchiopoda: Cladocera) in the Catalan Sea (NW Mediterranean, Journal of Plankton Research 30(4): 345-357

Atienza, Dacha; Saiz, Enric; Calbet, Albert (2006) Feeding ecology of the marine cladoceran Penilia avirostris: natural diet, prey selectivity and daily ration, Marine Ecology Progress Series 315: 211-220

Bamstedt, Ulf; Fossa, Jan Helge; Martinussen, Monica B.; Fosshagen, Audun (1998) Mass occurrence of the physonect siphonophore Apolemia uvaria (Lesueur) in Norwegian waters, Sarsia 83(1): 79-85

Bernier, Renee; Locke, Andrea (2006) New record of Penilia avirostris Dana, 1849 (Cladocera) in the Gulf of St. Lawrence, Crustaceana 79(8): 949-959

Calliari, Danilo; Tiselius, Peter (2009) Organic carbon fluxes through the mesozooplankton and their variability at different time-scales in the Gullmarsfjord, Sweden, Estuarine, Coastal and Shelf Science 85: 107-117

Catlett, J. G.; Harding, J. P. (1949) Penilia, a cladoceran normally found off tropical and sub-tropical coasts, recorded in North Sea plankton, Nature 164: 238-239

Colton, J. B. (1985) Eastward extension of the distribution of the marine cladoceran (Penilia avirostris) in the northwest Atlantic: a case of ecesis?, Journal of Northwest Atlantic Fisheries Science 6: 141-148

Cordell, Jeffrey R. and 5 authors (2009) Factors influencing densities of non-indigenous species in the ballast water of ships arriving at ports in Puget Sound, Washington, United States, Aquatic Conservation: Marine and Freshwater Ecosystems 19(3): 322-343

Dolgopol'skya, M. A. (1959) [Cladocera of the Black Sea], Trudy Sevatopolskoi Biologicheskoi Stantsii 10: 29-75

Durbin, Alan; Hebert, Paul D. N.; Cristescu, Melania E. A. (2008) Comparative phylogeography of marine cladocerans., Marine Biology 155: 1-10

Egloff, David A.; Fofonoff, Paul W.; Onbe, Takashi (1997) Reproductive biology of marine cladocerans, Advances in Marine Biology 31: 79-167

Fofonoff, Paul W. (1994) <missing title>, University of Rhode Island (Ph. D. dissertation), Kingston RI. Pp. <missing location>

Johns, D. G.; Edwards, M. ; Greve, W.; SJohn, A. W. G. (2005) Increasing prevalence of the marine cladoceran Penilia avirostris (Dana, 1852) in the North Sea, Helgoland Marine Research 59: 214-218

Johnson, William S.; Allen, Dennis M. (2005) <missing title>, Johns Hopkins Press, Baltimore. Pp. <missing location>

Lochhead, John H. (1954) On the distribution of a marine cladoceran, Penilia avirostris Dana (Crustacea, Branchiopoda), with a note on its reported bioluminescence, Biological Bulletin 107: 92-105

Miyashita, Leonardo K.; Pompeu, Mayza; Gaeta, Salvador A.; Lopes, Rubens M. (2010) Seasonal contrasts in abundance and reproductive parameters of Penilia avirostris (Cladocera, Ctenopoda) in a coastal subtropical area, Marine Biology 157: 2511-2519

Onbe, Takashi; Tanimyura, Atsushi; Fukuchi, Matsuo; Hattori, Hiroshi; Sasaki, Hiroshi; Matsuda, Osama (1996) Distribution of marine cladocerans in the northern Bering Sea and the Chukchi Sea, Proceedings of the NIPR Symposium on Polar Biology 9: 141-152

Piontkovski, S. A.; Fonda-Umani, S.; De Olazabal, A.; Gubanova, A. D. (2012) Penilia avirostris: Regional and global patterns of seasonal cycles, International Journal of Oceans and Oceanography 6(1): 9-25

Shiganova, Tamara (2010) Biotic homogenization of inland seas of the Ponto-Caspian, Annual Review of Ecology and Systematics 41: 103-125

Shiganova,T. A.; Musaeva, E. I. ; Pautova, L. A. ; Bulgakova, Yu. V. (2005) The problem of invaders in the Caspian Sea in the context of the findings of new zoo- and phytoplankton species from the Black Sea., Biology Bulletin 32: 65-74

Valentin, J. L.; Marazzo, A. (2004) Embryonic development time of Penilia avirostris Dana, 1852 in a tropical bay in Brazil, Brazilian Journal of Biology 64: 891-894

Wass, Melvin L. (1972) A checklist of the biota of lower Chesapeake Bay, Special Scientific Report, Virginia Institute of Marine Science 65: 1-290

Wong, C. Kim; Li, Vivian C. Y.; Chan, Ada (2008) Diel cycles of reproduction and vertical migration in the marine cladocerans Pseudevadne tergestina and Penilia avirostris, Journal of Plankton Research 30(1): 65-73