Vernal Pool Crustaceans

This file last modified: 03 June 2013

Preservation and handling instructions for vernal pool crustaceans

The Natural History Museum of Los Angeles County (NHM) is the repository of the nation’s second largest collection of crustaceans, second in size only to that of the USNM/Smithsonian Institution. The Museum is committed to the long-term care, curation, and growth of its collection. Our collections contain invaluable resources and are available for scientific study. We are pleased to accept and catalog high quality crustacean wet preserved specimens and dried resting eggs (often called “cysts”).

This document describes specimen preservation and locality information requirements. This information is useful for “large branchiopod” crustaceans (fairy and brine shrimp, tadpole shrimp, and clam shrimp) but applies equally well to all small freshwater crustaceans (e.g. copepods, ostracods, smaller branchiopods(cladocerans), amphipods, etc.). Check our website for updated versions of this document and associated resources: The modification date of this document appears at the end.

Our aim is to maximize the scientific value of your collecting efforts and the biological usefulness of specimens for future studies. This document provides a brief overview of (1) techniques and supplies needed for collecting in the field, (2) specimen handling in the laboratory, and (3) preparing specimens for transfer to the NHM. To make sample collecting and processing as simple and efficient as possible, collecting kits can be obtained from NHM (see Collecting Kits).

In the Field

Adult “large branchiopod” specimens are netted with an 1/8” mesh net (3,175 µm) or smaller. A 240 µm mesh net is needed to capture juveniles or larvae and smaller crustaceans such as cladocerans; 63 µm mesh is used for most copepods and ostracods. The dip net with specimens is gently rinsed to wash off sediment. With a funnel inserted into the mouth of a plastic whirl top bag, invert your net containing specimens over the funnel, and wash the specimens into the bag with 95% ethanol in a volume of 3:1 alcohol to specimen(s). Close the whirl top bag and drop the bag containing the specimens into a second whirl top bag. Use a number 2 pencil to write your unique field number on the label. Add the label to the outer bag and close the second bag. Move on to the next collecting site.

In the Lab

In the lab, cut the top off the outer bag, remove the label and set it aside. Having the label in a separate bag keeps the label from getting tangled with the specimens. Cut the top off the inner bag containing the specimens. Carefully pour the specimens into the same sized net used in the field. Invert the net over a petri dish, rinsing the sample with fresh 95% ethanol. Identify the specimens as usual.


Traditionally, specimens used exclusively for morphological studies have been fixed in 5–10% formalin (37% formaldehyde in solution, as commercially purchased, mixed with 90-95% water). Note that formalin fixation is no longer advised, since it makes the material unavailable for molecular genetic studies.

Rinsing specimens with freshwater has the advantage of removing flocculent material that can otherwise adhere to the specimens. If freshwater is not available in the field, directly preserving the specimens in 95% ethanol is the next best choice. High grade ethanol (not denatured) can be purchased from vendors listed on the page describing collecting kits. Absolute ethanol (100%) is less desirable than 95% ethanol, because it contains dehydrating agents that can impede subsequent molecular reactions. Also, 95% ethanol is less expensive than absolute ethanol.

In the past, we have sometimes received specimens that were preserved in acetone. It seems that researchers unable to obtain pure ethanol have been substituting denatured alcohol, which is cut (mixed) with acetone to make it denatured. Should you be unable to obtain pure ethanol, please substitute commercial alcoholic liquor (e.g. Everclear® 95% or 75.5%, 150-proof rum, or 150-proof vodka). While not ideal, this substitute increases the possibility that the specimens can be used for molecular genetic studies and is preferable to using denatured alcohol.

Regardless of the fixation/preservation method used, please tell us exactly how specimens were handled (see Collection Data below). The usefulness of your specimens is thus vastly increased.

Preparing for the Museum

A specimen lot is/are specimen(s) collected from a single locality during a single collecting event. The number of specimens in a lot may vary from as few as one (1) to many individuals. Individuals in a lot may be a single species or there may be many species (referred to as a mixed lot). As identification of specimens in a lot are refined (further subdivided), they are still associated with the original locality and collecting (event) information.

Place the identified specimens into a glass shell vial (1, 4, or 8 dram). Vial size is selected based on specimen volume, with 3:1 alcohol to specimen(s) ratio. Usually a 1.0 dram shell vial is suitable for lots containing 1–5 average-sized fairy shrimp. Use a 4 dram or 8 dram vial for more specimens. Use multiple vials if necessary to keep the alcohol:specimen volume at or above 3:1.

Completely fill the vial with 95% ethanol and stopper it with a 100% cotton plug (not foam, rayon, ro other synthetic fiber). Place the cotton stoppered glass shell vial into the plastic screw top shipping tube and add the label. Fill the shipping tube with 95% ethanol. Keeping the specimen separate from the label keeps the specimen(s) from becoming tangled with the label and consequently broken or damaged.

The label that is enclosed with the specimen(s) must, at minimum, contain the following information (other information is required in electronic format, see Collection Data below):

  • Specimen or lot identifier (i.e. unique identifier).
  • Date collected (see section on Collection Data below).

Collection Data

Each collection must be accompanied by the following information electronically and in hardcopy format. The “Specimen or lot identifiers” in these data must match the identifiers on the labels in the specimen vials (see Preparing for the Museum above).

  • Permitting agency name(s): agencies issuing the relevant collecting permit(s).
    [NOTE: collections submitted without the name of the permitting agency and the specific permit number will be refused].
  • Permit number(s): the specific permit number(s) under which the collections were made.
  • Company or agency responsible for collection.
  • Names of biologists performing collection.
  • [Optional] Names of other relevant personnel.
  • [Optional] Maps of collection sites or other geospatial documentation. This information increases the usefulness of the specimens. We will happily accept such accessory documentation in electronic or paper form.
  • [Optional] Digital photographs of the collecting site(s). These will be archived with your specimens.

Each lot within the collection must be accompanied by the following information:

  • Specimen or lot identifier: can be as simple as a unique number for each specimen or lot, whichever is appropriate. This can be the field collector’s number or other reference identifier that clearly links each specimen or lot to collecting/locality data and the fields enumerated below.
  • Date collected (date field).
  • [Optional] Time collected (only if this is part of your regular data stream).


  • Geography: from larger to smaller locality, e.g. “USA, California, San Diego County, La Mesa”
  • [Optional] Locality description: e.g. “near David’s School, from vernal pool 35 ft. west of Route 1.,” “Brown’s Pond, pool #3,” “tract 7, pool #1,” etc.
  • Latitude: e.g. “32.80154” or “32° 48' 5.544"”
  • Longitude: e.g. “-117.03313” or “117° 1' 59.2674" W”
  • Datum: reference ellipsoid used to specify the latitude and longitude, e.g. “WGS84” or “NAD83” or “GRS80“
  • Geolocation method: include information on how coordinates were determined, e.g. “GPS,” “estimated from 1:10,000 USGS topographic map,” “Google Earth map,” etc.
  • [Optional] Altitude: in meters

Collecting Event

  • Collector name(s).
  • Habitat information: e.g. “livestock-disturbed pool,” “fairy shrimp found under cobbles,” etc.
  • Collecting method(s) / device(s): e.g. “63 µm net,” “suction pump,” “SCUBA,” “hand,” etc.
  • Preservative: e.g. “95% ethanol,” “fixed in formalin, transferred to 70% ethanol,” etc.


  • Taxon: genus and species (or name of lowest known taxonomic rank)
    [Note: unsorted lots will be accepted without taxonomic identification].
  • Name of person making identification.
  • Date identified.
  • [Optional] Notes: can include any observations on behavior, co-occurring species, number of individuals in lot, sex, maturity, “identification based on adult males only,” etc.

All collection and lot information must be supplied electronically with a hardcopy accompanying the shipment. Our Excel data entry spreadsheet can be downloaded from the NHM Vernal Pool website (see Downloads below). If you have additional data, feel free to add columns to the spreadsheet for those data and we will do our best to incorporate them into our collection database. Additional digital resources (e.g. photographs, maps, reports, etc.) are also welcome.

Specimen number or lot number should be the first column. Collection date must be in date-format cells (not free-form “General” or “Text” formatted field). Latitude and longitude can be in the format collected in the field. If data are in decimal degrees, latitude should be in one column, longitude in a separate column. If data are collected in degrees and decimal minutes or another format, each number should be in a separate column (create new columns if needed).

Permit information (name of the agency issuing the collecting permit and the permit number) is legally required for us to accept samples. Permit numbers will be reported back annually to the U.S. Fish and Wildlife Service.

The Museum reserves the right to refuse specimens with inadequate amounts of usable collection data.

Long-term Storage

Archival quality materials (including high quality alcohol, glass vials, permanent ink or pencil on permanent label paper) should always be used. To minimize the amount of time and money involved with specimen handling, specimens should be placed in small glass shell vials. If you are collecting only a few samples, the simplest and least expensive option is to obtain one of our pre-made kits. For large collecting efforts, vendor information is available on the same web page.

Once specimens are received here at the Museum, permanent archival labels will be printed and your vialed specimens will be double-vialed for compact, long-term, easily retrievable storage. Cataloging information can be returned upon request.


Specimens should be shipped in the plastic screw-top shipping tubes, enclosed in Ziplock or heat-sealed bags to prevent leaking, and must be adequately cushioned with bubble-wrap, plastic peanuts, or other packing material to ensure their safe arrival. Specimens must be sent registered or certified mail or courier.

Please address packages to:

Natural History Museum of Los Angeles County,
Research and Collections, Crustacea
attention Adam Wall, Curatorial Assistant
900 Exposition Boulevard
Los Angeles, California 90007
Tel. 213 763-3450

Note: Donor accepts responsibility for compliance with the current rules and regulations for the shipping of hazardous materials.

Resting Eggs (“Cysts”)

The spherical, dry, resting form of fairy shrimps are “resting eggs”, though they are often called “cysts”. The term “cyst” properly refers to an adult resting stage that is covered in a resistant outer shell.

Identified resting eggs should be placed into 1 dram shell vials, cotton stoppered, and labeled the same way as the wet preserved specimens. The only difference is that resting eggs stay dry and are shipped dry.

Accessioning Cost

Because of the rising costs of accessioning and maintaining collections, the Natural History Museum reserves the right to charge for accessioning collections on a per-lot basis. This fee varies with the size of the collection, duration of the project, and availability of Museum staff at the time of deposition. The usual per-lot fee is $22 (this fee may be waived at the discretion of the Curator).

If specimen lots are not curated according to the guidelines in the current version of this document, a fee of $25 per lot will be charged, with a $200 minimum charge.

Accessioning Information

The Natural History Museum of Los Angeles County will accept selected collections of Crustacea for permanent care and curation, including those from vernal pools and other ephemeral freshwater habitats and representatives of threatened or endangered taxa. If properly curated, we will also accept associated fauna (i.e. bycatch). The Museum is willing to act as the repository for collections acquired during USFWS or other surveys.

To be accepted for accessioning, the collections must be in adequately preserved condition, meaning that the animals themselves must not have deteriorated and that all previously stated collecting, preserving, and labeling protocols have been followed. Furthermore, all collections must be accompanied by a detailed list of the specimens being sent as well as copies of any required permits.

The Museum reserves the right to decide whether an incoming collection should be stored topically versus separated and stored according to taxonomic divisions (i.e., storing all members of one family together rather than keeping all collections from one site together).

The Museum further reserves the right to decide which specimens will be maintained for long term storage and which may be passed on to other institutions in exchange or as long term loans for research purposes.

Visit our collection website at for more information about our holdings and information about our collections. If you have questions about proper handling, please email Adam Wall (, Regina Wetzer (, or Joel Martin ( for guidance in preparing your specimens for accessioning into our collections.

Ultimately, our specimens are stored with as much locality/collection information as will fit on a label. Associated data that cannot be included on the label for space reasons are always retained in our electronic database.

Collecting Kits

To make sample collecting and processing as simple and efficient as possible, collecting kits can be obtained from NHM.


This file last modified: 03 June 2013