44 NATURAL HISTORY. 



these animals are too commonplace, — but the bizarre " five-finger-jacks " 

 are so curious that they must have some peculiarity in every part of their 

 economy as well as of their anatomy ; and so they actually have. 



As has just been said, they feed on shell-fish, but their mode of feeding 

 is very peculiar. They have no teeth, so they cannot gnaw a hole through 

 the solid shells of their prey ; their mouth is small, and, further, is sur- 

 rounded by a bony framework, so that they cannot swallow the entire 

 animal, shell and all, as do some of the fishes. How, then, do they eat ? 

 "If the mountain will not come to Mahomet, then Mahomet will go to the 

 mountain." If the oyster will not go into their stomachs, then their stom- 

 achs will go out to the oyster. The starfish settles down upon the mussel, 

 wraps all his arms around it and holds it firmly by his numerous curious 

 tubular feet, and then sticks his stomach out through the mouth and wraps 

 it round the unfortunate mollusc. The oyster is soon killed ; its shell then 

 gapes, and into the interior goes this curious stomach, digesting, when thus 

 turned inside out, the animal which it could by no possibility swallow. 

 When the feast is concluded, the stomach is again safely tucked away in 

 the body of the starfish. 



The starfish does not need to move rapidly. His food is stationary j 

 and he does not fear enemies, since he is protected by his spiny coat. Still, 

 some motion is necessary, and this is effected principally by means of the 



tubular feet, already mentioned. These are 

 very peculiar organs, which are not confined 

 to the starfish, but are found in other Echino- 

 derms as well. Our figure shows three pairs 

 of these feet, each of which consists of an ex- 

 ternal tubular portion terminating in a sucking- 

 disc, and an internal globular portion. The 

 interior is filled with fluid, and hence when 

 the globular portion is contracted the external 

 fig. 45.— a few of the tubular feet of portion is extended. Other motions are con- 

 trolled by muscles ; and, further, all the feet 

 on one arm are connected with a tube running the whole length of the 

 arm. The starfish can extend one of these feet, attach it to some foreign 

 object, then extend another, and so on, until a firm hold is obtained, and 

 then the whole animal can be drawn along in the same way that a ship 

 "warps" its way up a channel against wind and tide. 



In the starfish, as in all the Echinoderms, there is none of that repro- 

 duction by budding or by division which is so common in the groups 

 already discussed. Reproduction by means of egg is the only mode, but 

 among the starfishes there is no alternation of generations. Each egg pro- 



