CHAPTER IV 



BRYOZOA (POLYZOA) 

 ECTOPROCTA 



AN ECTOPROCT BRYOZOAN (Bugula turrita) 



Bugula turrita is a marine colonial bryozoan which is very 

 common in the shallow waters along our coast. The colonies 

 are sessile and are attached to rocks, seaweed, and other objects. 

 The animals are very small and must be studied with the aid of 

 a microscope. 



Study a large piece of a colony (alive if possible) and notice 

 the spiral arrangement of the branches. A branch is made up 

 of a double row of elongated partitions or chambers, each of 

 which is called a zocecium. Each zocecium represents a separate 

 individual of the colony ; within its walls are the soft parts of 

 the animal which are called collectively the polypide. The indi- 

 vidual bryozoan is thus made up of two distinct parts, the 

 zocecium and the polypide, the former constituting the chitinous 

 outer wall of the animal, the latter comprising its viscera and 

 the tentacles. At its upper or distal end the zocecium has a 

 large opening through which the forward end of the polypide 

 can be protruded and into which it withdraws itself when 

 alarmed. The cuticula which forms the zocecium is rendered 

 hard by the presence of carbonate of lime ; it is thus much 

 more enduring than the remainder of the animal, and after 

 death the empty zocecium may persist long after all the 

 softer parts have disappeared. Look for empty zocecia in 

 your specimen. 



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