30 



THE STORY OF LIFE IN THE SEAS. 



Scallops which live in the darkness of the great 

 depths of the ocean are quite blind. 



Very interesting examples of the connection 

 between the presence of eyes and the power of 

 locomotion are found among the sedentary or 

 fixed forms of life. The great class of Sea-squirts 

 or Tunicates includes a number of genera, most 

 of which are, in the adult 

 condition, immoveably 

 fixed to the bottom, and 

 in that stage have no 

 eyes ; but the eggs which 

 they produce give rise to 

 little creatures, like tad- 

 poles in form, which swim 

 about freely in the water. 

 Each of these tad-poles 

 has a large eye in its 

 brain, which remains so 

 long as the animal leads 

 a free life. As soon, how- 

 ever, as it settles down 

 upon the rock which is 

 to become its permanent 

 resting place through life, 

 the eye and the organ of 

 locomotion, the tail, both 

 degenerate and ultimately disappear. Again, 

 we often find upon rocks, Sea-weed, old shells, 

 and the like, some curious delicate branching 

 organisms called Zoophytes. Notwithstanding 

 their general resemblance in form to Sea-weeds, 

 these Zoophytes are known to be animals. 

 Each tuft or branch is formed by a number of 



Fio. 6. A branch of the 

 Zoophyte Obelia. 



