Friday, July 31, 2020

Basics Of Zooplankton Identification



Essential anatomical terminology must be learned in order to positively identify an organism.

General elements that need to be assessed for all zooplankton groups are:

1. body shape and size

2. relative length of various appendages, including antennae, legs, and setae

3. presence and relative sizes of spines

 

Although several anatomical features used to differentiate species are listed in the literature, this Guide only makes mention of the key details which taxonomists use for rapid identifications. The attempt was to keep the list of features to a minimum while ensuring accurate species assignments. Although some dissection may be required, this Guide generally only depicts anatomical details that can be viewed under a dissection microscope. For more detailed information on certain features (ex. cyclopoid 5th legs), refer to the sources listed in Section 4.

 

After gaining some experience, you will develop a mental picture of what a typical specimen of each common species looks like. Therefore, although first identifications will take time in order to consult the literature and keys, this will not always be a necessary step. Each zooplankton group has a series of major characteristics used for positive identification. Once you memorize what to look for the speed of processing will dramatically increase. If ever in doubt, always refer to the keys.

 

If an identification is still uncertain after following these steps, it is always best to adopt a more general designation rather than take a “guess”. For example, the taxonomy of Bosmina is notoriously complicated by the elements mentioned in the introduction to this Guide. Very fine distinctions separate members of the 5 species found within the Sudbury Region. Therefore, if in doubt, assign a member of this family to the proper genus (i.e. Eubosmina or Bosmina) rather  than attempting a tentative species designation.

 

Identification to the family (for Cladocera) or order (for Copepoda) level is fairly easy. From there you must refer to the main identification characteristics for each group, outlined in the following Sections.

 

Writer

Jessintya Palupi

Fisheries Tech Brawijaya University 2014

 

Editor

Gery Purnomo Aji Sutrisno

Fisheries Tech Brawijaya University 2015

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