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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: Eastern grass shrimp

Synonyms and Other Names: Eastern Grass Shrimp (Walls 2009), Florida Ghost Shrimp, Ghost Shrimp, Glass shrimp, Glass Prawn, Popcorn Shrimp (Anderson 1985).

Taxonomy: available through www.itis.gov

Identification: Palaemonetes paludosus is a small translucent shrimp with tiny red specks throughout the body on some, but not all, specimens (Page 1985, Fofonoff et al. 2016). This species has a humped abdomen at the third segment and large pigmented eyes (Page 1985). Bright green intestines can be seen through the body (Walls 2009). Mature females greater than 20 mm in total length carry spherical eggs at about 1 mm in diameter that can also be seen through the body (Page 1985, Walls 2009). Males and females are dimorphic with males having unique first and second pleopods “swimming legs” (Baranowski 2011). This species is similar in appearance to other Palaemonetes species (grass shrimp) but can be identified by a set of four characteristics.

1. The number of rostrum “horn” teeth for the species is between 6 -8 on the dorsal side and 3-4 on the ventral side (Anderson 1985, Page 1985, Walls 2009).

2. The posterior telson spines of the “tail fin” are more regularly positioned (Walls 2009). See below for the link to figure of shrimp anatomy.

3. The branchiostegal spine is at the front edge of the carapace on the branchiostegal groove (Walls 2009). See below for the link to figure of shrimp anatomy.

4. Palaemonetes paludosus can be differentiated from P. kadiakensis by the number of large spines at the tip of the male second pleopods “swimming legs” P. paludosus has four and P. kadiakensis has three (Page 1985, Walls 2009). Note: strong magnification is needed to see this characteristic.

Size: Up to 50 mm total length (Baranowski 2011)

Native Range: Palaemonetes paludosus is native to the Atlantic coastal plain from southern New Jersey to Florida (Hayden et al. 1963; Beck and Cowell 1976; Thorp and Covich 2010).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology: Palaemonetes paludosus is primarily found in low gradient freshwater habitats but can also be found in brackish conditions in salinities from 0-10 ppt (Tabb and Manning 1961). In laboratory experiments, Palaemonetes paludosus specimens have survived in salinities to 30 ppt (Swingle 1971). Although P. paludosus is considered a freshwater shrimp, it can complete its life cycle in brackish water (Lowe and Provenzano 1990). This shrimp can be found on the bottoms (benthos) of wetlands and streams associated with dense living submerged aquatic vegetation and clear water (Hayden et al. 1963, Turner et al. 1975, Page 1985, Baranowski 2011). In summer months, this species can be found in high abundance among semi-aquatic grasses and water hyacinths (Eichhornia crassipes) (Baranowski 2011). Its preferred water temperature range is 10° to 35° C (Christmas and Langley 1973).

Palaemonetes paludosus is an omnivorous nocturnal feeder (Turner et al. 1975) that mainly feeds on algae (diatoms and green algae) but will also consume living vascular plants (Nielsen and Reynolds 1975, Beck and Cowell 1976), aquatic insects (Beck and Cowell 1976) and detritus from both plants and animals (Nielsen and Reynolds 1975, Beck and Cowell 1976).

Palaemonetes paludosus reproduce sexually. This species has an annual life cycle and will die post-spawning from April to October (Beck and Cowell 1976). Breeding season for this species varies with location and temperature of the water. Breeding in the more northern portion of the range usually occurs between early February and mid-October at water temperatures of 18 to 33°C. However, P. paludosus breed year-round in the warmer waters of the southern portion of its range in Florida and can breed twice per year (Beck and Cowell 1976). A female will have 8 to 85 eggs in a mass (Beck and Cowell 1976), which will hatch after an incubation period of approximately 12 to 14 days at 26° to 28°C (Dobkin 1963). This shrimp’s larvae are free-swimming and will grow 3.25 mm per month in the summer and fall. Larval development for this species has been described in detail by Dobkin (1963). Juvenile shrimps mature in the spring and are reproductive around one year of age and then die (Page 1985).

Means of Introduction: Most likely through aquarium (Fofonoff et al. 2016) or bait releases as the species is used as bait and fish food, especially in trout hatcheries (Holthuis 1952).

Status: Palaemonetes paludosus is established in various locations in Arizona, California, Louisiana, Texas and Oklahoma (Hayden et al. 1963, Beck and Cowell 1976, Lowe and Provenzano 1990, Walls 2009). However, it was found to be extirpated in 1962 from Picacho pond in Imperial National Refuge, Arizona/California (Hayden et al. 1963).

Impact of Introduction: There are no documented economic or ecological impacts for this species (Baranowski 2011). These shrimps are an important food source for many fish species, especially juvenile crappie (Pomoxis sp.) and black bass (Micropterus sp.) (Hayden et al. 1963, Baranowski 2011). Palaemonetes paludosus provide an important link between benthic and water column habitats, helping energy flow and turnover of detritus (Baranowski 2011). 

Remarks: On August 27, 1958 approximately 225 P. paludosus were planted in Lower Colorado drainage in Lake Havasu pond, Arizona/California, and 1,000 specimens were planted in three ponds in the Imperial National Refuge, Arizona/California on November 1, 1958. The three ponds in Imperial National Refuge were: Taylor Lake pond, Picacho pond, and Imperial Camp bait pond.  The California Department of Fish and Game and the Arizona Game and Fish Department returned to the sites during the spring and summer of 1962 to determine the status of the shrimp populations.  Shrimp were found in all sites except the Picacho pond.  It was hypothesized that the shrimp did not survive in Picacho pond due to intensive fish predation.  The Imperial Camp bait pond had the largest established population (Hayden et al., 1963).

In January and Marsh of 1963, 1,100 shrimp were taken from the Imperial Camp bait pond in Arizona and transplanted into seven sites:  Branson's Resort (AZ), Marina Village (AZ), Lost Lake Camp in Alligator Slough, backwater below the Palo Verde Weir (AZ), the Palo Verde Drain (CA), Lake Havasu (AZ/CA), and Havasu Landing lake pond (Hayden et al., 1963).

References: (click for full references)

Anderson, G. 1985. Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (Gulf of Mexico): grass shrimp. U.S. Fish Wildl. Serv. Biol. Rep. 82(11.35) U.S. Army Corps of Engineers, TR EL-82-4.

Baranowski, C. 2011. Palaemonetes paludosus, Animal Diversity Web. http://animaldiversity.org/accounts/Palaemonetes_paludosus/. Accessed on 08/28/2017.

Beck, J.T., and B.C. Cowell. 1976. Life history and ecology of the freshwater caridean shrimp, Palaemonetes paludosus. The American Midland Naturalist 96(1):52-65.

Christmas, J.Y., and W. Langley. 1973. Estuarine vertebrates, Mississippi. Cooperative Gulf of Mexico Estuarine Inventory and Study: 320-434.

Dobkin, S. 1963. The larval development of Palaemonetes paludosus (Gibbes, 1850) (Decapoda, Palaemonidae), reared in the laboratory. Crustaceana 6(1):41-61.

Fofonoff, P.W., G.M. Ruiz, B. Steves, and J.T. Carlton. 2016. National Exotic Marine and Estuarine Species Information System. Smithsonian Environmental Research Center, Washington, D.C. http://invasions.si.edu/nemesis/. Accessed on 08/29/2017.

Hayden, R. P. and R. D. Ringo. 1963. Introduction of Palaemonetes paludosus, a freshwater shrimp, into the lower Colorado River. California Fish and Game, 49(4), 304-306.

Holthuis, L.B. 1952. A general revision of the Palaemonidae (Crustacea Decapoda Natantia) of the Americas. ii. the subfamily Palaemoninae. Volume 12. The University of Southern California Press, Los Angeles, CA.

Lowe, B.T. and A.J. Provenzano Jr. 1990. Survival and reproduction of Palaemonetes paludosus (Gibbes, 1850) (Decapoda: Palaemonidae) in saline water. Journal of Crustacean Biology 10(4):639-647.

Nielsen, L. A., and J. B. Reynolds. 1975. Fresh-water shrimp natural food for pond fishes. Farm Pond Harvest 9(2):8-9.

Page, L.M. 1985. The crayfishes and shrimps (decapods) of Illinois. Ill. Nat. Hist. Surv. Bull., 33(4):335-447.

Swingle, H.A. 1971. Biology of Alabama estuarine areas - cooperative Gulf of Mexico estuarine inventory. Ala. Mar. Res. Bull 5:1-123.

Tabb, D., and R.B. Manning. 1961. A check 1ist of the flora and fauna of northern Florida Bay and adjacent brackish waters of the Florida mainland collected during the period July 1957 through September 1960. Bulletin of Marine Science of the Gulf and Caribbean 11:554-649.

Thorp, J.H., and A.P. Covich. 2010. Ecology and Classification of North American Freshwater Invertebrates (Third Edition). Academic Press, Elsevier Inc, San Diego, CA. http://www.sciencedirect.com/science/book/9780123748553.

Turner, R., Lowe, E. and J. Lawrence. 1975. Isosmotic intracellular regulation in the freshwater palaemonid shrimp Palaemonetes paludosus. Physiological Zoology 48(3):235-241.

Walls, J.G. 2009. Crawfishes of Louisiana. Louisiana State University Press, Baton Rouge, LA.

Other Resources:
See Shrimp News International for the anatomy of a shrimp: http://shrimpnews.com/FreeReportsFolder/GeneralInformationFolder/AnatomyShrimp.html

Author: Daniel, W.M.

Peer Review Date: 9/24/2019

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.