The Mighty Deep 



crabs seem to know perfectly well from which 

 kinds of sea-weed or zoophyte they may snip off 

 little bits, with a prospect of not killing them. 



So unerring, indeed, is their knowledge in this 

 respect, that, as an authority on the subject has 

 stated, "the keepers of Aquaria have only to 

 consult the crabs to learn what kinds of sea- 

 animals will bear being thus transplanted piece- 

 meal"* 



Is this too merely " instinct " ? 



Many a time baits were lowered in the nets 

 of the Challenger to attract victims. Oddly 

 enough, it was found that no more effective bait 

 could be used for crabs and their kindred than 

 pieces of looking-glass ! May one imagine that 

 some friendly Medusa lent her little glimmer, far 

 below, to enable the Hermit-crabs, when putting 

 on fresh ribbons, to see their reflections, and 

 judge of the effect ? It reads rather like a page 

 of Alice in Wonderland. 



Hermit-crabs or Soldier-crabs, having an in- 

 sufficient protective armour of their own, are in 

 the habit of using empty Mollusc shells to shelter 

 that part of their bodies which is not guarded. 

 One of these crabs, when young, chooses a 

 shell, fitted to its size; and when grown too 



* Crustacea, by STEBBING. 

 228 



