Crabs, Lobsters, Shrimps, Barnacles, etc. (Crustacea). g? 



anemones, for their common good. We can soon see that the 

 hermit-crab is the real soul of the company, its founder and 

 president, but the anemone is by no means a sleeping partner. 

 We know already how concerned the crab is about the safety of 

 his soft body; but even within the whelk-shell he does not con- 

 sider it really secure — and that not without good reason, since 

 it is no trouble for a turtle to crack the shell or for an octopus to 

 squirt some poison into it (p. 89). Experiment has shown, how- 

 ever, that in the presence of the anemones these enemies keep 

 their distance: while octopods pounce at once upon hermit-crabs 

 in naked shells, they do not dare to touch those to which anemones 

 are fixed — their past experience of the stinging-cells of the anemone 

 overcomes their appetite for hermit-crab. Tiius the crab has 

 this advantage from the association, that his house is overgrown 

 by living batteries of stinging-cells, the fire from which puts his 

 enemies to flight. The anmone, too, gets her share, for she walks 

 around on the agile legs of her friend; and this is not only an 

 imexpected pleasure for a beast condemned to sit still through- 

 out life — these promenades bring a more material gain. If one 

 watches a Pagurus eating, or two fighting for a tasty bit of food, 

 the anemone always gets the crumbs which fall from the table 

 of her friend. And so that nothing shall be lost the little sea- 

 anemone Adamsia palliata, the regular companion of Eupagurus 

 Pridauxii (fig. 144) sits on the shell so that her mouth is turned 

 downwards. 



The way in which the association of these two diverse life- 

 companions is kept up and how it is re-established after disturb- 

 ances presents to us a difficult problem in' animal psychology. 

 For the hermit-crab decorates his house with sea-anemones himself 

 and if one takes the anemones away from the shell and scatters 

 them about in different places in the Aquarium, the crab collects 

 them again and holds them with his claws on the shell until they 

 have attached themselves again. And the same thing takes place 

 on changing houses : he does not leave his old companions behind 

 on the cast off shell, but takes them off and carries them over to 

 the new one. Moreover, while the anemones shoot out their 

 sting-cells at any other touch, they allow their friend the hermit 

 to do what appears to him good. 



In the same tank (No. 23) other curious things are to be seen 

 running around: yellow or bluish lumps at one side of which is 

 a hole with a hermit-crab looking out of it. These too are whelk- 

 shells, but so overgrown by a sponge {Suherites), that the form 

 of the shell is often quite unrecognizable. At the same time 

 the sponge dissolves the calcareous substance of the shell until 

 eventually there remains only the hole inhabited by the crab. 



The life of the Hermit-crabs in the Aquarium is rich in varied 

 and amusing scenes. The droll flights of the little troop, the way 



6* 



