A COPEPOD 49 



by the rhythmic contractions of the intestine. Other copepods 

 possess a dorsal heart. There are no special respiratory organs. 

 How is respiration carried on? The excretory system consists 

 of a pair of coiled tubes, called the shell glands, which lie in the 

 forward part of the cephalothorax and have external openings 

 near the base of the first pair of thoracic appendages. 



The reproductive system consists of a median tubular organ in 

 the dorsal portion of the cephalothorax above the intestine. 

 In the female this organ is the ovary, and the large ova can 

 often be seen in it. The oviducts are paired and lead to the 

 external sexual openings in the first abdominal segment. 

 Appended to the first abdominal segment may be a pair of 

 egg-sacs into which the eggs pass after being fertilized by 

 spermatozoa from the spermatophore which the male has placed 

 upon the female. In the male the reproductive gland is the 

 median testis, which communicates by means of paired vasa 

 deferentia with the external sexual openings also in the first 

 abdominal segment. The spermatozoa collect in the terminal 

 portion of each vas deferens and form in each a small mass 

 known as a spermatophore. The two spermatophores, during the 

 act of pairing, pass to the female and fertilize the ova. The 

 male animals are much less numerous than the females. 



The reproductive glands of the copepod can be observed as 

 above described only during times of sexual activity. At other 

 times they can be seen only in part or not at all. 



The muscular system can be easily seen to consist of striated 

 muscle fibers. Longitudinal as well as converging fibers will 

 be seen at each appendage. 



The nervous system may be seen in favorable specimens as a 

 ventral strand in the cephalothorax connecting with the large 

 dorsal brain. 



Exercise 4. Draw a side view of the animal showing as many of 

 the internal organs as you have observed. 



