STARFISHES 163 



from a little patch of coralline only two or three inches square. 

 These have such small discs, and such slender arms, and are, more- 

 over, so well concealed by their colouring, which closely resembles 

 that of the weed-tuft they inhabit, that they are only to be detected 

 by close inspection. 



The remaining division of the starfishes, sometimes distinguished 

 by the name of Common Stars, possess five arms or rays, which may 

 be either long or short, and which are not jointed with the central 

 disc, but continuous with it ; that is, there is no sharp line of demar- 

 cation between arm and disc. One or two species are well known 

 to all frequenters of the sea-side, but the majority of them inhabit 

 deep water, where they creep about over the rocks and weeds, 

 obtaining their food from the bed below them. 



If we examine the common five-finger star that is so often 

 stranded on the beach, and so frequently found in rock pools between 

 the tide-marks, we see that each arm has a large and conspicuous 

 groove running along its centre on the under side, and on each side 

 of these are the rows of tube-feet, arranged in such a manner that 

 they have suggested the appearance of an avenue of trees on each 

 side of a garden walk, and have consequently earned the name of 

 ambulacrum. These tube-feet may be protruded for some distance ; 

 and, being provided with suckers that possess considerable clinging 

 power, they form the principal means of locomotion. 



Put the starfish in the aqnarium, or in a tidepool by the sea, 

 and you will find it very interesting to observe how the animal pro- 

 gresses, while some idea of the clinging power of the tube-feet may 

 be ascertained by allowing the animal to creep over the submerged 

 hand. 



The movements of the tube-feet may also be seen to advantage 

 when the starfish is laid upside down in a pool, and, what is still 

 more interesting, the manner in which the animal turns itself over. 

 To do this it will first bend the tips of one or two of its arms so as 

 to bring the suckers against the ground ; and then, aided by the 

 pulling action of these, it will gradually bring other suckers into a 

 similar position till, at last, the whole body has been turned over. 

 Some of our common starfishes have rays so short that they may be 

 termed angles rather than arms, and these are unable to turn their 

 inverted bodies by the gradual method just described. They 

 generally raise their bodies on the tips of three or four of the rays, 

 assuming somewhat the form of a three- or four-legged stool, and 

 then, bending the remaining one or two arms over the body, they 



