DAPHNIA, CYCLOPS, ARGULUS 187 



1. Watch the animals and see how they swim. With a 

 pipette try to catch a certain individual and see whether the 

 jerky movements probably aid these animals in escaping 

 enemies. Determine what organs are used in swimming. 



2. With a microscope examine specimens that have been 

 confined under a cover glass, and notice the shape of the 

 body. Into what parts is it divided? Count the number of 

 segments. Look for evidence of fused segments. Notice how 

 the spines on the abdomen are arranged. 



3. Do you find eyes that are equivalent to the usual ar- 

 thropod eyes? Do you find an eye spot? If such a spot is 

 found, determine its position and shape. 



4. Which pair of antennae is larger? Why are the large 

 antennae fringed with spines? 



5. Are there thoracic or abdominal appendages? Are any 

 appendages other than the first antennae used in swimming? 



6. The mouth parts consist of mandibles and two maxillae. 



7. If the specimen is a female it may have two large egg 

 sacs attached to the sides of the base of the abdomen. The 

 female has two of the abdominal segments fused. In the 

 male the segments are free. 



A drawing of the specimen is desirable. 



Fish: Seasonal Distribution of the Plankton of the Woods Hole Region. 



Bull. Bur. Fisheries, vol. 41, Doc. 975, 1925. 

 Heath: The External Development of Certain Phyllopods. Jour. 



Morph., vol. 38, No. 4, 1924. 

 Sharpe : Notes on the Marine Copepods and Cladocera of Woods Hole 



and Adjacent Regions, Including a Synopsis of the Genera of the 



Harpocticoida. Proc. U. S. Nat. Mus., 38, 1910. 

 Wheeler: Free-Swimming Copepods of the Woods Hole Region. Bull. 



U. S. Fish Com., 19, 1899. 



ARGULUS (Fish-louse) 



These animals may be found on many species of fresh- 

 water and marine fish. Notice their shape and determine 

 how they cling to their host. Are they able to crawl? Can 

 they swim? 



