COELENTERATES 



SEA ANEMONE 



Metrideum sp. 



Observe the shape and general contour of the body. 

 Distinguish between the upper and lower disks. Study the 

 lower disk. What does its shape and form indicate as to its 

 use? Is the animal free in the water or attached to some- 

 thing? If attached, how? Draw the lower or basal disk 

 (XI). 



Examine the upper disk. Find the mouth, the lips and the 

 tentacles. Are the tentacles arranged in a definite order? 

 Are they of the same length? Is the mouth alike in all 

 parts? Notice the extremities of the mouth to find any 

 thickening or specialization of any kind. Draw the animal 

 from the side showing the cylindrical barrel and the upper 

 disk. 



With a scalpel cut the body into two parts at right angles 

 to the barrel. 



This exposes the tube on the inside which extends down 

 from the mouth. This is called the esophagus. Look below 

 the esophagus for another coelenteric chamber limited by the 

 wall of the body of the animal and divided, or partially so, 

 by radially arranged partitions called septa, or mesenteries. 

 Examine the septa closely. How many extend to the coelen- 



T17 



