40 LIFE BY THE SEASHORE. 



and at most should contain only two or three small animals. 

 If it is kept carefully cleaned, and has fresh water added to 

 make up for loss by evaporation, it will be found unneces- 

 sary to change the water for a very long period. In such 

 a dish many of the shore animals will live well, and there 

 is much more chance that you will really observe the habits 

 of your pets if each one has a dish to itself than if they 

 are placed in a crowded aquarium among many other 

 animals. The points of special importance are : do not 

 crowd, and do not use a vessel which holds a great bulk 

 of water proportionate to the surface exposed to the action 

 of the atmosphere. Some shore animals, such as the com- 

 mon crab, the common limpet, and others, will only live 

 where they are partially exposed to air, and a great number 

 are much more sensitive to impurities in the water than to 

 a partial exposure of their surface to the atmosphere. 

 Finally, in keeping marine animals in confinement, do not 

 forget that the object, as well as the justification of the 

 practice, is that you may observe their habits ; therefore do 

 not forget to look at them, to notice their changes, to draw 

 them if possible. 



The Coelentera, or sea-nettles, as the German popular 

 name may be translated, form a very large group, including 

 a number of different kinds of animals. The most obvious 

 common character is the presence of tentacles, which bear 

 the stinging-cells to which the German name refers. Let 

 not the name alarm the sensitive naturalist, however, for, as 

 already mentioned, in this country, except in the case of 

 the jelly-fish and such southern forms as the " Portuguese 

 man-of-war," these stinging-cells will not penetrate our skin. 

 We may begin our study of the group by examining a very 

 delicate and harmless little creature, one of the zoophytes or 

 animals like plants. If you examine the shore pools with a 

 little care, you will find a number of spiral shells lying 

 apparently loose at the bottom, with their surface often 

 covered with a brown or pinkish crust. As you watch, the 

 apparently empty shells will move away with considerable 

 speed, disclosing the long legs of a hermit-crab as they do 

 so (see Fig. 3). Pick out the shell in which the surface 

 crust seems to be best marked, and drop it into a shallow 

 dish filled with sea-water. In a few minutes the hermit 



