Juliette Nowak and Judith Quist worked together on the key as members of the 2000 Zooplankton Ecology course at UNH under the guidance of Dr. James Haney . They were responsible for the conceptual design of the key as an interactive PowerPoint show and production of the 2000 version. All photos used in the key were taken by members of the class or graduate student Richard Hathaway. The key included 2 genera of Copepoda, 6 genera of Cladocera (14 to species), 7 genera of Rotifera (9 to species) and 4 other genera. Extensive Daphnia and Bosmina/Eubosmina anatomy pages were included.

Maria Aliberti, Shane Bradt, and Sara Greene worked on the key as members of the 2002 Zooplankton Ecology course at UNH under the guidance of Dr. James Haney . They were primarily responsible for building on the previous version through improvement of the key design in PowerPoint and the addition of numerous organisms. Significant design improvements included the addition of a species list and group list to enter the key at various taxonomic levels, individual end pages for each species and self-linking pages to prevent accidental advancement through the key. All images were from the previous version of the key or taken during the class. Their work was released in 2003 as version 1.0. The key included 6 genera of Copepoda (9 to species), 12 genera of Cladocera (23 to species), 9 genera of Rotifera (10 to species) and 4 other genera (4 to species). The Daphnia and Bosmina/Eubosmina anatomy pages were retained.

Shane Bradt prepared the Version 1.0 for release from May 2002 until January 2003. This process involved troubleshooting, standardization of pages, creation of a PDF version of the key useful for non-computer use, and design of the CD. In March of 2003, Shane gave an oral presentation about the key at the New England Association of Environmental Biologists Annual Meeting, initiating collaboration with Dr. Richard Stemberger of Dartmouth College.

In late spring of 2003, Dr. Richard Stemberger provided his extensive image archive and taxonomic expertise for the key, especially in the Rotifera. His images were first incorporated into the key in the summer of 2003 by Shayle Reed and Amy Kaplan. Their efforts resulted in a improved rotifer section of the key, and lead to the release of Version 1.1 in November of 2003. This version included 8 genera of Copepoda (9 to species), 12 genera of Cladocera (25 to species), 14 genera of Rotifera (51 to species) and 4 other genera (4 to species).

Shane Bradt was again responsible for preparing Version 1.1 for release and distributing the key at the North American Lake Management Society Annual International Symposium in November 2003.

Darren Bauer, Sonya Carlson, Travis Godkin, Shawn Melillo, and Brian Ortman further developed the key as members of the 2004 Zooplankton Ecology course at UNH under the guidance of Dr. James Haney . Four students were assigned a section of the key based on the breakdown of Cladocera (Darren), calanoids (Travis), cyclopoids (Brian) and Rotifera (Shawn), while Sonya was given the task of coordinating key restructuring, including the migration of the key to HTML format. The comprehensive redesign and conversion of the key to HTML was a major project led by Brady Carlson. HTML provided many advantages: operating system and software independence, a more manageable update procedure, the ability to have multiple people working on the key at one time, the easy incorporation of video clips, and the option to have the key used online.

Students used images from the previous Zooplankton Ecology classes, captured their own images, incorporated additional rotifer images from Dr. Richard Stemberger, and used images of calanoids and cyclopoids provided by two online keys from the USGS (Hudson et al. 2003, Lesko et al. 2003). Design improvements include standardization of layout, indication of the level of taxonomy throughout the key, the widespread adoption of removable labels, and graphics indicating the location of features in reference to the entire organism for Cladocerans, cyclopoids and copepods. This version includes 17 genera of Copepoda (29 to species), 13 genera of Cladocera (25 to species), 18 genera of Rotifera (70 to species) and 4 other genera (4 to species). In March 2004, Sonya Carlson presented a poster about the key at the New England Association of Environmental Biologists Annual Meeting , to further expand the group of potential users.

Shane Bradt, Brady Carlson, Sonya Carlson, Travis Godkin, Dr. James Haney, and Tiffany Rowin have worked to ready the key for release since June of 2004. This effort included troubleshooting, completion of the transition to html, improving image quality, addition of numerous images and videos, and some key restructuring. A draft version of the key was posted on the CFB website on October 1, 2004. Dr. Richard Stemberger and Margret Chriscinske provided many useful comments and suggestions after in-depth reviews of the key in early 2005. Shane Bradt was largely responsible for the implementation of these changes. Version 2.0 was finalized on March 11, 2005 is currently available online at the CFB website and on CD. This version includes 17 genera of Copepoda (28 to species), 14 genera of Cladocera (33 to species), 22 genera of Rotifera (79 to species) and 4 other genera (4 to species).

The Zooplankton Ecology classes of the spring of 2006 and 2007 worked to improve the key by adding more detailed information on the ecology of numerous species, led by Sonya Carlson, Amanda Murby and Dr. James Haney. Over the course of those two years, Wendy Beagen coordinated the production and editing of the enhanced species pages. The students of the spring 2007 class also created and added videos on sampling methods. Virtual focus videos were captured in the summer of 2007 by Amanda Murby, Elisha Allan, Erin Maroni, Monika Schmuck and Uyen Mai Doan. Later in the summer, Shane Bradt worked with Dr. James Haney, Amanda Murby and Elisha Allan to integrate the videos into the key. A preview of the key progress was released at the 2007 SIL conference in Montreal as the Special SIL Edition.

Version 3.0 of the key was released in March of 2009. Major improvements included addition of new taxa, expansion of the species pages, virtual focus, sampling instructional videos, and inclusion of genetic barcoding. In 2008, Wendy Beagen and Stacy Farina edited and augmented the comprehensive species pages, including web development of the pop-up figures and tables. Stephanie Allard, Katie Conrad, Cammie Kwong, Monika Schmuck, Jonathan Bunker and Jonathan Dufresne created virtual focus movies and added many new images to improve the quality of the key. Carol Elliott composed and edited the instructional sampling method videos taken in the spring of 2007 by members of the Zooplankton Ecology class. Stacy Farina assisted Elisha Allan in the integration of genetic barcoding information for five cyclopoid and six calanoid copepod species. Amanda Murby provided technical assistance and coordinated the preparation of Version 3.0. She also made the final web changes to the key. Shane Bradt was our web consultant and general "trouble-shooter". Jim Haney encouraged and supervised the continuing evolution of the key.

In November, 2010, the key was updated to Version 4.0. Stephanie Allard began expansion of the rotifer section, selecting many of the images from the Stemberger collection. Breanna Travers created the final choice and species pages adding 30 species of rotifers to the key. Through persistent sampling of the littoral and benthic regions, Jonathan Dufresne added 28 new benthic cladoceran species from 20 genera. Jon also worked on updating and improving photos and choice pages throughout the key. With the new additions, version 4.0 contains 113 rotifers and 108 arthropods for a total of 221 taxa in the key. Version 4.0 was brought to completion with much coordination and direct help of Amanda Murby. As current webmaster for the UNH Center for Freshwater Biology, Amanda, along with web consultant Shane Bradt, supervised all web-related changes in the key. As always, Jim Haney contributed ideas, support and enthusiasm.

Version 5.0 was released in May, 2013. A major change was the addition of species from across North America and the renaming of the key to reflect this broader coverage to: An Image-based Key to the Zooplankton of North America. Although the key does not yet have complete coverage of all zooplankton species across North America, we will continue to add new species with each new version of the key. Most of the species added were identified and photographed from the 2007 US EPA National Lakes Assessment, a program that sampled zooplankton and water quality from 1157 lakes from across the contiguous United States. Hilary Snook, US Environmental Protection Agency Region 1 Laboratory, provided the UNH Center for Freshwater Biology with over 10,000 zooplankton samples and financial support for the identification and imaging of specimens and their incorporation into the taxonomic key. Jonathan Dufresne, assisted by Jesica Waller and Elizabeth Orlowicz, took on the enormous job of cataloging the EPA samples and imaging new specimens. Jon also worked on the taxonomic organization for the added species and he updated many choice and species pages throughout the key. Teodoro Rosati provided improved images of Brachionus variabilis.

Additions to Version 5.0 include 23 new organisms, 20 were identified to species, of which 14 are calanoid copepods. Choice pages have been redesigned for the calanoid copepods and images were updated on more than 30 species and choice pages. Numerous movies have been added by Jim Haney that depict feeding and reproductive behavior of zooplankton. Webmaster Amanda Murby continues to enthusiastically supervise the project and provide valuable technical help with the development and installment of the new version. Jim Haney gently guided the zooplankton key through this important phase of its evolution.

Here are some “key” trivia: based on Google Analytics data collected from January 1, 2010 to May 16, 2013, 165,000 visitors viewed more than 1.2 million pages of the key from 176 countries/territories in 126 languages. Following the United States, the most frequent users came from Canada, United Kingdom, Brazil and India. The top five “most searched organisms” were Daphnia magna, Daphnia pulex, Moina macrocopa, Brachionus calyciflorus and Asplanchna priodonta. Judging from the frequency of selections on the first choice page of the key, the most “keyed” taxa were Cladocera (31%), Rotifers (23%), Copepods (20%) and other arthropods (7%).