210 THE LIFE OF CRUSTACEA 



chambers, profiting no doubt by the respiratory 

 currents and the food particles they carry. 



A great variety of Crustacea find shelter and 

 defence in association with Sponges, Corals, and 

 other more or less sedentary animals. Sponges are 

 not eaten by many marine animals, the needle-like 

 spicules which often form their skeleton no doubt 

 helping to render them distasteful, and many small 

 Crustacea, Amphipods, Isopods, Prawns, etc., profit 

 by their immunity from attack, and take up their 

 abode in the internal channels and cavities of the 

 Sponge. The beautiful siliceous Sponge known as 

 " Venus's Flower-basket" (Euplectella) very often 

 contains imprisoned within it specimens of a delicate 

 little Prawn {Spongicola venusta) or of an Isopod 

 {Mga spongiophila). As these Crustacea share with 

 the Sponge the food particles drawn in by the currents 

 of water passing through the pores in its walls, they 

 are in the strict sense commensals. 



The Corals and various other animal organisms 

 commonly known as " Zoophytes," forming together 

 with the Jellyfishes the group Coelentera, are very 

 effectively protected against the attacks of most 

 predatory animals by the possession of " stinging 

 cells," and this protection is shared by many other 

 animals which shelter among them. Thus, the 

 branching Coral stocks which grow in great luxuri- 

 ance on tropical coasts support a rich and varied 

 assemblage of animals, some of which may actually 



