Thamnocephalus platyurus - Packard, 1877
Beavertail Fairy Shrimp
Taxonomic Status: Accepted
Related ITIS Name(s): Thamnocephalus platyurus Packard, 1877 (TSN 83750)
Unique Identifier: ELEMENT_GLOBAL.2.108478
Element Code: ICBRA18020
Informal Taxonomy: Animals, Invertebrates - Crustaceans - Fairy, Clam, and Tadpole Shrimps
Kingdom Phylum Class Order Family Genus
Animalia Crustacea Branchiopoda Anostraca Thamnocephalidae Thamnocephalus
Genus Size: A - Monotypic genus
Check this box to expand all report sections:
Concept Reference
Concept Reference: Eriksen, C. H. and D. Belk. 1999. Fairy Shrimps of California's Puddles, Pools, and Playas. Mad River Press: Eureka, California.196 pp.
Concept Reference Code: B99ERI01EHUS
Name Used in Concept Reference: Thamnocephalus platyurus
Conservation Status

NatureServe Status

Global Status: G5
Global Status Last Reviewed: 08Oct2008
Global Status Last Changed: 21Jun2000
Rounded Global Status: G5 - Secure
Reasons: Occurring in pools throughout the Great Plains, and southwestern deserts.
Nation: United States
National Status: N5 (21Jun2000)

U.S. & Canada State/Province Status
United States Arizona (SNR), Arkansas (SNR), California (SNR), Colorado (SNR), Iowa (SNR), Kansas (SNR), Missouri (SNR), Montana (SNR), Nebraska (SNR), Nevada (SNR), New Mexico (SNR), Oklahoma (S4?), Texas (SNR), Utah (SNR), Wyoming (SNR)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent: 200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Range Extent Comments: Widespread from Wyoming to Missouri to central Mexico and west to California (Eriksen and Belk, 1999).

Number of Occurrences: 81 to >300
Number of Occurrences Comments: Rogers (2006) cites specimens from Durano, Mexico; Cochise Co., Arizona; Cibola, Grant, Harding, Luna Cos., New Mexico. Dexter (1953) cites occurrences from Kansas, Colorado, Oklahoma, Texas, Arizona, and San Luis Potosi in Mexico; with new records from Nevada, New Mexico and California. Hossack et al. (2010) provided documented records for Montana from Powser River and Valley Cos.

Population Size: >1,000,000 individuals

Number of Occurrences with Good Viability/Integrity: Unknown

Other NatureServe Conservation Status Information

Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) Widespread from Wyoming to Missouri to central Mexico and west to California (Eriksen and Belk, 1999).

U.S. States and Canadian Provinces
Color legend for Distribution Map
Endemism: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States AR, AZ, CA, CO, IA, KS, MO, MT, NE, NM, NV, OK, TX, UT, WY

Range Map
No map available.

Ecology & Life History
Habitat Type: Freshwater
Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: N
Palustrine Habitat(s): TEMPORARY POOL
Habitat Comments: Occurs in alkaline, turbid, warm water temporary playas.
Economic Attributes Not yet assessed
Management Summary Not yet assessed
Population/Occurrence Delineation
Group Name: Phyllopodous Branchiopods

Use Class: Not applicable
Minimum Criteria for an Occurrence: Occurrences are based on some evidence of historical or current presence of single or multiple specimens of mature adult males at a given location with potentially recurring existence. Often both males and females are necessary for identification to the specific level. Evidence is derived from reliable published observation or collection data; unpublished, though documented (i.e. government or agency reports, web sites, etc.) observation or collection data; or museum specimen information. Photographs, diagnostic or not, are not acceptable for minimum occurrences.
Mapping Guidance: Due to the stochastic nature of local species distribution, map each pool, or series of pools within 100 m of one another, as separate occurrences.
Separation Barriers: Separation barriers are based on hydrological discontinuity. Any hydrological discontinuity, including presence of upland habitat, greater than 100 m constitutes a separation barrier. Note that dried ponds or pools that refill annually or cyclically are not considered separation barriers as phyllopodous branchiopod eggs are capable of dormancy in a resting stage typically lasting 6 to 10 months in temperate latitudes (Smith, 2001). In laboratory conditions, eggs have been reared from the resting stage years later.

Separation Distance for Unsuitable Habitat: 1 km
Separation Distance for Suitable Habitat: 1 km
Alternate Separation Procedure: Freshwater cave (troglobitic) species may occur from near entrances to very deep in cave systems. For cave species, each cave where an observation or collection was recorded (see Minimum EO Criteria, above) constitutes an element occurrence regardless of separation distance unless caves are part of a single hydrological system (see below). Occurrences are additionally separated by underground physical barriers to movement. Multiple caves within a single hydrological cave system are considered to be a single element occurrence when they are less than one km apart. Multiple caves within a single hydrological cave system are considered separate element occurrences when hydrological connections have not been determined or when separated by a distance of at least one km.
Separation Justification: Phyllopodous Branchiopoda (Crustacea: Anostraca, Notostraca, Laevicaudata, Spinicaudata) include the fairy, tadpole, and clam shrimps, respectively. They inhabit temporary ponds and pools and are absent from running water. Most species have few specific habitat preferences (Smith, 2001) occurring in most often in small (seldom exceeding one hectare) roadside ditches, vernal pools; as well as small to large permanent and (to a much lesser degree) temporary ponds. Rogers and Fugate (2001) report finding Branchinecta hiberna from railroad bed toe-drains and roadside ditches as small as 0.15 m2.

Species typically occur in the absence of fish. Presence of fish, though not considered a separation barrier for EO SPECS purpooses, is a very strong indicator of phyllopod absence and a barrier to dispersal. Rare exceptions occur when anostracans are found in large, deep freshwater lakes where fish predation is very low (Branchinecta in Canada- Anderson, 1974; Cyclestheria hislopi- Olesen et al., 1996). Species often have high tolerance to fluctuations in osmotic pressure, oxygen concentration, salinity, alkalinity, pH (though they prefer alkaline waters). Phyllopodous branchiopods typically have one (or two) generations each time potential habitat is made available often only hatching only some of the eggs at any given time while cyst banking the remainder (Belk and Cole, 1975; Loring et al., 1988; Ripley et al., 2004) so a major strategy is to produce as many small resistant eggs as possible in the shortest amount of time that aestivate and then hatch when the pool fills again.

Separating populations can be exceedingly difficult because a species may be abundant for several successive years, then be absent unaccountably for one or two years, then mysteriously return. Adults tend to be restricted to their area of occurrence only, and, although minimum separation distance has been set at only one km and some random dispersal by predators may occur (see below), phyllopods are usually present in scattered pools with nearby pools completely absent, for whatever reason. This may be attributed to stochastic distribution patterns resulting from dispersal of resting eggs by wind or transported by birds or insects that visit branchiopod habitat to drink or breed (Loring et al., 1988). Recently, resting eggs of the European fairy shrimp, Chirocephalus diaphanus, were shown to survive ingestion by trout and subsequent freezing and re-incubation in the laboratory without losing viability indicating fish may aid in dispersal of some species of fairy shrimp (Beladjal et al., 2007). Only subtle generic differences among populations of anostracans, even when close to each other (Boileau et al., 1992), suggests dispersal rate is either very low or completely random. Diversity in Arizona, for example, depends mainly on chemical heterogeneity among (mostly temporary) habitats; and thermal variation resulting both from ponds filling at different seasons and from altitudinal and latitudinal effects (Belk, 1977; Eng et al., 1990).

Date: 09Feb2007
Author: Cordeiro, J.
Population/Occurrence Viability
U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
NatureServe Conservation Status Factors Edition Date: 08Oct2008
NatureServe Conservation Status Factors Author: Rogers, D.C.
Element Ecology & Life History Edition Date: 08Oct2008
Element Ecology & Life History Author(s): Rogers, D.C. (2008); Cordeiro, J. (2004)

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

  • Dexter, R.W. 1953. Studies on North American fairy shrimps with the description of two new species. American Midland Naturalist 49:751-771.

  • Eriksen, C. H. and D. Belk. 1999. Fairy Shrimps of California's Puddles, Pools, and Playas. Mad River Press: Eureka, California.196 pp.

  • Hossack, B.R., R.L. Newell, and D.C. Rogers. 2010. Branchiopods (Anostraca, Notostraca) from protected areas of western Montana. Northwest Science 84(1):52-59.

  • McLaughlin, P.A., D.K. Camp, M.V. Angel, E.L. Bousfield, P. Brunel, R.C. Brusca, D. Cadien, A.C. Cohen, K. Conlan, L.G. Eldredge, D.L. Felder, J.W. Goy, T. Haney, B. Hann, R.W. Heard, E.A. Hendrycks, H.H. Hobbs III, J.R. Holsinger, B. Kensley, D.R. Laubitz, S.E. LeCroy, R. Lemaitre, R.F. Maddocks, J.W. Martin, P. Mikkelsen, E. Nelson, W.A. Newman, R.M. Overstreet, W.J. Poly, W.W. Price, J.W. Reid, A. Robertson, D.C. Rogers, A. Ross, M. Schotte, F. Schram, C. Shih, L. Watling, G.D.F. Wilson, and D.D. Turgeon. 2005. Common and scientific names of aquatic invertebrates from the United States and Canada: Crustaceans. American Fisheries Society Special Publication 31: 545 pp.

  • Rogers, D. C. 2013. Anostraca catalogus (Crustacea: Branchiopoda). The Raffles Bulletin of Zoology 61(2):525?546.

  • Rogers, D.C. 2006. A genus level revision of the Thamnocephalidae (Crustacea: Branchiopoda: Anostraca). Zootaxa, 1260: 1-25.

  • Saunders, J.F., III. Eubranchiopoda of Colorado, Part 2. Anostraca. Natural History Inventory of Colorado 6: 1-23.

Use Guidelines & Citation

Use Guidelines and Citation

The Small Print: Trademark, Copyright, Citation Guidelines, Restrictions on Use, and Information Disclaimer.

Note: All species and ecological community data presented in NatureServe Explorer at were updated to be current with NatureServe's central databases as of November 2016.
Note: This report was printed on

Trademark Notice: "NatureServe", NatureServe Explorer, The NatureServe logo, and all other names of NatureServe programs referenced herein are trademarks of NatureServe. Any other product or company names mentioned herein are the trademarks of their respective owners.

Copyright Notice: Copyright © 2017 NatureServe, 4600 N. Fairfax Dr., 7th Floor, Arlington Virginia 22203, U.S.A. All Rights Reserved. Each document delivered from this server or web site may contain other proprietary notices and copyright information relating to that document. The following citation should be used in any published materials which reference the web site.

Citation for data on website including State Distribution, Watershed, and Reptile Range maps:
NatureServe. 2017. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia. Available (Accessed:

Citation for Bird Range Maps of North America:
Ridgely, R.S., T.F. Allnutt, T. Brooks, D.K. McNicol, D.W. Mehlman, B.E. Young, and J.R. Zook. 2003. Digital Distribution Maps of the Birds of the Western Hemisphere, version 1.0. NatureServe, Arlington, Virginia, USA.

Acknowledgement Statement for Bird Range Maps of North America:
"Data provided by NatureServe in collaboration with Robert Ridgely, James Zook, The Nature Conservancy - Migratory Bird Program, Conservation International - CABS, World Wildlife Fund - US, and Environment Canada - WILDSPACE."

Citation for Mammal Range Maps of North America:
Patterson, B.D., G. Ceballos, W. Sechrest, M.F. Tognelli, T. Brooks, L. Luna, P. Ortega, I. Salazar, and B.E. Young. 2003. Digital Distribution Maps of the Mammals of the Western Hemisphere, version 1.0. NatureServe, Arlington, Virginia, USA.

Acknowledgement Statement for Mammal Range Maps of North America:
"Data provided by NatureServe in collaboration with Bruce Patterson, Wes Sechrest, Marcelo Tognelli, Gerardo Ceballos, The Nature Conservancy-Migratory Bird Program, Conservation International-CABS, World Wildlife Fund-US, and Environment Canada-WILDSPACE."

Citation for Amphibian Range Maps of the Western Hemisphere:
IUCN, Conservation International, and NatureServe. 2004. Global Amphibian Assessment. IUCN, Conservation International, and NatureServe, Washington, DC and Arlington, Virginia, USA.

Acknowledgement Statement for Amphibian Range Maps of the Western Hemisphere:
"Data developed as part of the Global Amphibian Assessment and provided by IUCN-World Conservation Union, Conservation International and NatureServe."

NOTE: Full metadata for the Bird Range Maps of North America is available at:

Full metadata for the Mammal Range Maps of North America is available at:

Restrictions on Use: Permission to use, copy and distribute documents delivered from this server is hereby granted under the following conditions:
  1. The above copyright notice must appear in all copies;
  2. Any use of the documents available from this server must be for informational purposes only and in no instance for commercial purposes;
  3. Some data may be downloaded to files and altered in format for analytical purposes, however the data should still be referenced using the citation above;
  4. No graphics available from this server can be used, copied or distributed separate from the accompanying text. Any rights not expressly granted herein are reserved by NatureServe. Nothing contained herein shall be construed as conferring by implication, estoppel, or otherwise any license or right under any trademark of NatureServe. No trademark owned by NatureServe may be used in advertising or promotion pertaining to the distribution of documents delivered from this server without specific advance permission from NatureServe. Except as expressly provided above, nothing contained herein shall be construed as conferring any license or right under any NatureServe copyright.
Information Warranty Disclaimer: All documents and related graphics provided by this server and any other documents which are referenced by or linked to this server are provided "as is" without warranty as to the currentness, completeness, or accuracy of any specific data. NatureServe hereby disclaims all warranties and conditions with regard to any documents provided by this server or any other documents which are referenced by or linked to this server, including but not limited to all implied warranties and conditions of merchantibility, fitness for a particular purpose, and non-infringement. NatureServe makes no representations about the suitability of the information delivered from this server or any other documents that are referenced to or linked to this server. In no event shall NatureServe be liable for any special, indirect, incidental, consequential damages, or for damages of any kind arising out of or in connection with the use or performance of information contained in any documents provided by this server or in any other documents which are referenced by or linked to this server, under any theory of liability used. NatureServe may update or make changes to the documents provided by this server at any time without notice; however, NatureServe makes no commitment to update the information contained herein. Since the data in the central databases are continually being updated, it is advisable to refresh data retrieved at least once a year after its receipt. The data provided is for planning, assessment, and informational purposes. Site specific projects or activities should be reviewed for potential environmental impacts with appropriate regulatory agencies. If ground-disturbing activities are proposed on a site, the appropriate state natural heritage program(s) or conservation data center can be contacted for a site-specific review of the project area (see Visit Local Programs).

Feedback Request: NatureServe encourages users to let us know of any errors or significant omissions that you find in the data through (see Contact Us). Your comments will be very valuable in improving the overall quality of our databases for the benefit of all users.