A COPEPOD 55 



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 median or paired organs in 

 the dorsal portion of the cephalothorax above the intestine. In 

 the female the ovaries are often conspicuous as a pair of large 

 branched organs. The oviducts are paired and lead to the exter- 

 nal sexual openings in the first abdominal segment. Appended 

 to the first abdominal segment may be a pair of egg-sacs contain- 

 ing fertilized eggs which are cemented together by means of a 

 secretion of the oviduct. In the male the reproductive gland is 

 the median testis, which communicates by means of paired vasa 

 deferentia with the external sexual openings, which are also in 

 the first abdominal segment. The spermatozoa collect in the 

 terminal portion of each vas deferens and form there a small 

 mass known as a spermatophore. The two sperm atophores, 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. 



