Current number of accepted species: 14 913
Current number of sources: 86 841
Current number of sources with fulltext attached: 54 151

What is a copepod?

Copepods are small aquatic crustaceans and are one of the most numerous metazoan groups in aquatic communities. Copepods inhabit a huge range of salinities, from fresh water to hypersaline conditions, and they can be found virtually everywhere there is water; from subterranean caves to pools collected in bromeliad leaves or in damp leaf litter on the ground, from streams, rivers, and lakes to the open ocean and the sediment layers beneath. Their habitats range from the highest mountain lakes to the deepest ocean trenches and from the cold polar ice-water interface to the hot active hydrothermal vents. Copepods may be free-living, symbiotic, or internal or external parasites on almost every major metazoan phylum. Adults typically have a body length in the 1-2 mm range, but adults of free-living species may be as short as 0.2 mm or as long as 17 mm. In the case of parasitic forms on large vertebrate hosts, body lengths may exceed 20 cm. Ecologically the planktonic copepods provide functionally important links in the aquatic food chain feeding on the microscopic algal cells of the phytoplankton and, in turn, being eaten by juvenile fish and other planktivores, including some whales. In fresh water copepods have the potential to act as a biological control mechanism for malaria by consuming mosquito larvae. However, they also serve as intermediate hosts of many animal parasites and even parasites of humans, including the fish tapeworm and guineaworm.

Although they belong to a separate class of crustaceans, Branchiura (commonly referred to as fish lice) are dealt with here along with the Copepoda, since many copepod researchers also study these external parasites of fish and amphibians. Most live in freshwater but about a quarter of species are marine. Together the Copepoda and Branchiura comprise over 200 described families; 2 600 genera and over 21 000 described species (both valid and invalid, including senior and junior synonyms).

The Copepoda currently comprises 10 Orders

  1. Platycopioida
  2. Calanoida
  3. Misophrioida
  4. Canuelloida
  5. Gelyelloida
  6. Harpacticoida
  7. Mormonilloida
  8. Cyclopoida
  9. Siphonostomatoida
  10. Monstrilloida

[Based on Khodami et al., 2017] The Poecilostomatoida is no longer recognised as a valid order; instead its component families lie on a well defined "poecilostome" lineage wholly contained within the Cyclopoida.

The Class Branchiura comprises 1 Family (the Argulidae) and 4 valid genera:

Argulus foliaceus
  1. Argulus
  2. Chonopeltis
  3. Dipteropeltis
  4. Dolops


Usage of data from the World of Copepods in scientific publications should be acknowledged by citing as follows:

If the data from the World of Copepods constitute a substantial proportion of the records used in analyses, the chief editor(s) of the database should be contacted. There may be additional data which may prove valuable to such analyses.

Individual pages are individually authored and dated. These can be cited separately: the proper citation is provided at the bottom of each page.

NEW TAXONOMIC INFORMATION (Lists all taxa in a genus and who published on them)

Recently we have added 2 valuable information resources to this site: the C.B. Wilson and J.S. Ho 3x5 taxonomic card collections. These are files of the 3x5 card collections of these 2 researchers that have been scanned Slava Ivanenko & Chad Walter, and saved as pdf files. The Wilson cards were started by Charles B. Wilson in the 1890's when he started recording all copepod taxa and any publications that mentioned the taxa. These cards had been kept up to date till about 1999 by staff at the Smithsonian Institution. With the advent of the various web based information services we stopped maintaining these cards. These cards are an invaluable resource as they record all the sources of literature that mention a specific taxa within a genus. The J.S. Ho cards were started by Ju Shey Ho and are based primarily on the taxonomy of parasitic copepods and include the synonomies of the taxa. Both of these data sources can be found under 'Links' on the genus page of the copepod taxa. Just search on a genus and then click on the 3x5 taxonomic card link and a pdf will appear providing you with all known publications referring to the copepod genus and all the species reported on, typically including the pages, figures, plates and or table information.

Editorial board


T. Chad Walter
Smithsonian Institution
Museum of Natural History
1000 Constitution Ave, MW
Washington, DC. 20560-0163

Geoff Boxshall
Natural History Museum; Department of Zoology
Cromwell Road
London, SW7 5BD, UK

Associate Editors

The Wilson and Monoculus Libraries

The Wilson Copepod Library was established in honor of Charles B. Wilson, a copepod researcher who was affiliated with the Smithsonian Institution, USA (1901 -1941). His library and well as other Smithsonian curators, Arthur Humes, George Grice and others was the basis of the library. The copepod library was later digitally created by T. Chad Walter and others, and contains all the known literature for copepods and branchiurans. At present 86 841 bibliographic entries on copepods are in the database. The Library has been maintained for over 30 years by T. Chad Walter and Janet Reid. We gratefully accept donations of literature on all aspects of the Copepoda, and request that you send us a copy of all your future publications. If you provide us with your pdf's or reprints in a timely fashion then we can quickly put your taxonomic information into the WoRMS database.

In 2012, the digital Wilson Library was migrated to the WoRMS website "The World of Copepods" and is referred to as the Virtual Copepod Library (VCL). The website is hosted on the WoRMS website, managed by the Flanders Marine Institute (VLIZ) in Belgium.

The VCL and website is constantly being updated by Geoff Boxshall, T. Chad Walter and Associate Editors, with 54 151 PDFs linked to bibliographic records. If any errors or problems noted please contact the Editors.

The Monoculus Library established in the 1980’s is located at the Forschungsinstitut Senckenberg, Germany attn: Pedro Martnez Arbizu. The library is managed by Ms. Jeannette Schöndube and she has provided 1000’s of pdf’s that are linked to the Virtual Copepod Library, the goal is to have the contents of both libraries available in the VCL.

Copepod Links for further information about copepods.

Below are a few other sites dealing with Copepods: [Use your web search engines and search on copepod for additional sites.]

This database was originally housed at the Smithsonian Institution, as the World of Copepods website, which was just a flat file database. That database was migrated into WoRMS since this is a relational database that allows for: linking synonymies, distributions, hosts, images, literature sources and specimen data. In addition, it allows for multiple editors to correct and edit data. In order to provide sufficient expert knowledge for maintaining the list, we have formed an editorial committee which will be editing and improving this database. This database will hopefully promote the stability in copepod nomenclature and act as a tool for higher taxonomic revisions and regional monographs and then provide a base link for other online databases that use copepod nomenclature.