44 THE STORY OF LIFE IN THE SEAS. 



fishes. The former possess spherical or heart- 

 shaped bodies covered with a formidable array of 

 spines, among which there protrude several rows 

 of soft transparent tubes terminating in little 

 cup-like discs. Some of these tubes or tube- 

 feet as they are called are fixed to a rock, and 

 the heavy body is slowly dragged after them; 

 another set is then attached, whilst the former 

 is released to obtain another hold a little further 

 on. The progress is slow, but the Urchin is able 

 to climb the smooth face of an absolutely per- 

 pendicular rock with perfect ease or to get over 

 any other obstacles that may be in its path. The 

 Star-fishes are similarly provided with tube-feet, 

 but in their case these are confined to the lower 

 surface of the body, the upper side being entirely 

 devoid of them. Star-fishes have a very wide 

 distribution in the sea, and occur on sandy shores 

 as well as among rocks and shingles. If a speci- 

 men be watched gliding slowly and smoothly 

 over the sea-bottom and then the mouth be 

 examined with a pocket lens, a doubt might 

 arise in the mind of the young naturalist as to 

 the justice of the charge that is made against 

 these animals of their being the principal enemies 

 of the hard-shelled Oysters. But the charge is 

 well founded, for if a Star-fish be placed in an 

 aquarium with an Oyster or a Cockle, or, in fact, 

 almost any bivalve Mollusc, it may be seen to 

 clasp its prey in its arms and slowly but firmly 

 and surely force open the shells, arid then pro- 

 trude on to the soft parts a long tubular stomach 

 which gradually digests and absorbs them. The 

 Star-fishes, then, are undoubtedly to be reckoned 



