APPENDIX 245 



Other species of marine animal. One day, however, after a 

 colleague had drawn my attention to it, I discovered the 

 explanation at Dahlak Kebir. While I was watching these 

 holes from the surface I saw one of the inmates slipping out of 

 his crater, without any apparent reason, to take up position 

 at the bottom of the sand heap, as if expecting something. 

 Thereupon a big claw slowly emerged from the aperture, 

 followed by a thin pair of antennae and the body of a large 

 prawn. While the right claw was held out in front, the left 

 one was held close into the cephalothorax and supported a 

 quantity of sand. Not in the least intimidated by my presence 

 or perhaps not aware of me, the prawn climbed the gentle 

 slope of its sand-hill and discharged its load with a decisive 

 movement of its claw when it had reached the top. The 

 sand, which was large-grained, slid down to the base of the 

 heap. The prawn then went slowly back into its hole and the 

 fish darted back into its original position sticking half into 

 and half out of the entrance. Its small lively eyes continued 

 to stare at me as if conscious of the danger inherent in my 

 presence. I did not move. I wanted to see if the scene would 

 be repeated. And in fact, after a few seconds, the blennius 

 darted back to the side of the cone followed by the prawn 

 with another load that was discharged alongside the first 

 one. In this way the mound grew uniformly larger on all 

 sides. 



One fact was now quite clear. The prawn was the arcliitect 

 and builder. But what was the function of the fish ? I have 

 thought that this might be a case of cohabitation combined 

 with the sharing of food. Besides acting as a guard the 

 blennius might possibly see to the victualling. Yet it remains 

 a mystery — at least to me. 



I had my observations checked by my colleagues and they 

 repeatedly confirmed my reports. 



