HYDROIDS 



67 



When the young hydroid first begins to grow, it looks 



like the fresh water hydra (Figure 60). 



As the hydroid grows, branches 

 form and on the end of each branch, 

 tentacles and a mouth appear. 



Figure 66. — A Hy- 

 droid Colony that 

 Looks like a 

 Plant. 



Figure 67. — A Hydroid Medusa. 



Each branch is able to capture food and, after it takes 

 what it needs, the surplus is distributed to other parts. 

 This is easily brought 

 about, as a common 

 digestive cavity con- 

 nects all of the branches. 

 The hydroid is termed 

 a colony because all of 

 the branches are united 

 and help each other in 

 getting enough food for 

 all. 



Some of the hydroids 

 form curious buds which 

 develop into medusce 

 (me-du'se). See Figure 



^ ° Figure 68. — The Medusa Known as 



bi. As soon as the Pelagia 



