CURIOSITIES OF STAR-FISH LIFE. 



365 



on down the ray. Usually two or three adjacent rays perform this 

 manoeuvre simultaneously, the spirals of the co-operating rays being 

 invariably turned in the same direction, and, when they have proceeded 

 sufficiently far to drag over the remaining rays, these then abandon 

 their hold on the bottom so as not to offer any resistance to the lifting 

 action of the active rays. The whole movement does not occupy more 

 than half a minute. 



But it is in the case of echinus that these righting movements 

 become most interesting, from the fact that they are so much more 

 difficult to accomplish. Two, or perhaps three, adjacent rows of suck- 

 ers are chosen out of the five to accomplish the task. As many feet 

 in these rows as can reach the floor are thrust downward and fastened 

 firmly to it ; by their combined action, as by the pull of liliputian ropes, 

 the globe is tilted slightly in their own direction, the anchoring feet in 

 the opposite rows releasing their hold on the floor to admit of this tilt- 

 ing (Fig. 8). The next feet in the active rows are thus enabled to 

 reach the floor, and, when they have established their hold, they assist 

 in increasing the tilt ; then the next feet in the series lay hold, and so 

 on, the globe slowly but steadily rising until it stands upon its equa- 

 tor (Fig. 9). The difficulty of raising such a heavy mass into this 



Fig. 9. 



position by means of the slender motive power available is manifest 

 not only from the extreme slowness with which it takes place, 

 but because specimens not perfectly strong may fail completely to 

 reach the position of resting on the equator. Moreover, in some 

 cases when this position has been reached with difficulty, the echinus 

 gives itself a breathing-space, as it were, before beginning its descent. 

 It will be perceived that, as soon as the descent begins, gravity is no 

 longer an obstacle but an aid to the righting movement, and it might 

 be anticipated that the echinus would now simply let go all its attach- 



