6:10 The livery of the triggerfish B.2 is getting clearer, repeatedly a 

 white spot develops, then fades out. B.l remains dark and stays near its 

 night shelter; sometimes it tries to enter it, but the place is occupied 

 by the moray. B.2 becomes active but without going off the block, it 

 forages something on the sand or on a big spheric sponge. The Thalassoma 

 start to awake, the first to be seen is the larger of the family. Damsel- 

 fishes have a more active, jerky and higher swimming. 



6:20 B.2 is getting again clearer for a moment; it swims in an excited 

 manner, close by the block. B.l stays in dark livery before its hollow or 

 comes up to the block and eats something on it. These two fishes seem to 

 wait for a signal. 



6:25 The jawfishes and the tilefish wake up, the last one cleans i-ts 

 burrow. The triggerfish B.2 does a succession of false starts during which 

 it goes further and further away and becomes clearer and clearer. 

 Getting brighter too, B.l also begins to stand away from the microcosm. 



6:40 At last this couple of fishes depart together towards the NW 

 algal flats. As for bed time, the triggerf ishes ' rising is being enact- 

 ed according to a very precise ceremonial. More generally, the start and 

 the fall of the activity of most species seem to be induced by definite 

 and specific light levels; and so the species that retire earliest are 

 also the last to awaken. 



Social Organization and Trophic Inter-relations 



According to these fragmental observations, the microcosm appears as an 

 example of a balanced animal society; the arrangement and the social 

 organization of which maintain this equilibrium. This balance is seen in 

 the fact that all available places are occupied at all times and that no 

 inhabitant remains without a shelter; and also in a harmonious corres- 

 pondance between the production and the consumption of food. 



Normal saturation of available places 



All the places are occupied. The occupation relay of the main crevice 

 between the moray + the squirrelfish during daytime and the triggerfishes 

 at night is a good example. The most active motile species (fishes) are 

 involved in action against the peril of a supernumerary occupation by 

 foreigners. So, for instance, at the end of a morning, a 20 cm small 

 triggerfish is repulsed by the biggest damselfish which bites it and drives 

 it out of the microcosm boundaries. Another day, at dusk, the same (?) 

 small triggerfish is driven away by the squirrelfish and the triggerfish 

 B.l. This is an interesting social behavior: the microcosm inhabitants, 

 as Holocentrus and Pomacentrus , that would not be directly penalized by 

 an additional occupant participate actively in its elimination. 



Productivity-consumption balance 



In order that the community composition remains steady, the feeding of the 

 inhabitants and of the foreigners must equilibrate the microcosm producti- 

 vity. All the trophic levels are present in the community. According to 



VI-289 



