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 zowcium. 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 zoccium may persist long after all the 
softer parts have disappeared. Look for empty zoccia in 
your specimen. 
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