positions in niches and crevices to come out in the open after dai 

 Neither were seen to travel more than 10 cm from the outer lip of 

 the crevice in any one night. The following day they were always 

 found in the same hole or in a hole within a distance of 10 cm. 



The difference in homing behavior between Diadema antillarum and 

 D. mexicanum may merely reflect a difference in habitat and may not 

 be due to a biological difference. The rocky reef in which D. 

 mexicanum was studied consisted generally of large boulders and 

 appeared to have much fewer crevices and holes adequate as refuge 

 for Diadema as compared with the reef in Lameshur Bay which has a 

 complex topography. It is curious, however, that the D. mexicanum 

 were never observed to exchange positions among themselves. 



SHRIMP 



1, Alpheus armatus . The sea anemone, Bartholomea annulata , is 

 often associated with the snapping shrimp, Alpheus armatus . 

 Limbaugh et a_l. (1961) found that when shrimp were removed from an 

 anemone, the anemone was preyed upon within a few days. However, 

 the predator was not identified. In order to identify the predator 

 of the anemone and to test the significance of the shrimp- anemone 

 association, we removed snapping shrimp from 13 Bartholomea . Five 

 anemones from the main reef were cleared of Alpheus , one for a 14- day 

 period, the others for 4 days. Six anemones from the patch reef area 

 north of the Tektite habitat were cleared of Alpheus for four days 

 each. In no case was the Bartholomea damaged by predators during 

 the observation period. The predator of the anemone appears to have 

 been scarce in the vicinity of the Tektite habitat during the latter 

 part of May, 1970. 



Two additional Bartholomea annulata from the main reef area (west of 

 the Tektite habitat) were found naturally lacking associated Alpheus 

 armatus and apparently surviving quite well. The Bartholomea from 

 which a pair of shrimp had been removed for 14 days was naturally 

 recolonized by a single shrimp, apparently after the eleventh day. 

 This shrimp was removed as soon as it was discovered. 



Alpheus armatus generally occurred in pairs and would not tolerate 

 additional Alpheus under their anemone. We attempted to introduce 

 additional Alpheus to one Bartholomea . Six and eight individuals 

 were added on two occasions. In each case, all the shrimp quickly 

 disappeared into the burrow of the anemone and no interaction with 

 the resident pair was observed. However, only 2 Alpheus were present 

 by the following morning on each occasion. 



2. Periclimenes spp. and Stenopus spp. Shrimp of several species 

 which remove parasites and damaged tissues from reef fishes may be 

 extremely important functionally in the coral reef community in spite 



VI-67 



