74 GLIMPSES OF NATURE. 



John Chinaman when at home. Now, our sea-cucumber, 

 in place of being either star-shaped or ball like, has a 

 body of somewhat elongated form. At the mouth end 

 it has tentacles, and along its body there are five rows 

 of tube-feet. So that, just as we may suppose a star- 

 fish to be a spread-out sea-urchin, we may compare 

 our sea-cucumber to a sea-urchin drawn out length- 

 wise. All three types of the starfish family-circle, in 

 fact, are modelled on one and the same broad plan. 



So much for the near relations of the sea-urchin, 

 or "sea-egg," as it is also named when, with all its 

 spines torn off, you find its shell lying on the shore. 

 We pop it into our glass tank, and in a short time, as 

 sketched in the above illustration, you find it climbing 

 up the side of its abode. That aperture you see in the 

 middle of the body is its mouth, and if you look closely 

 at this opening you may see projecting therefrom the 

 tips of the five teeth or jaws, which form the so-called 

 " Lantern of Aristotle." By aid of these jaws, set in 

 movement by a complex set of muscles, our Echinus 

 contrives to masticate the seaweeds and other tid-bits 

 on which it subsists. 



Notice next how the sea-urchin climbs on the glass. 

 These round white spots (each with an aperture in the 

 middle) which are disposed in five rows running up and 

 down the shell from top to bottom, you perceive, on 

 closer examination, to be tube-feet (similar to those 

 of the starfish), each capable of active movement. 

 These feet can be withdrawn into the shell. They 

 are protruded through holes in the limy casing when 

 movement is the aim of sea-urchin existence ; and in 

 order to become tense and stiff, and thus enabled to 

 support the body, the feet are distended with water. 

 When not required for movement, the water is ejected 



