COACTION IN LAMP-COMMUNITIES 23-5 



examples of more simple cases which are considered to lack some so- 

 cial components. 



A. Prey and predators coexisting with the objeci' fishes. 



The observations were made in the area near Shirahama situated 

 on the west coast of Kii peninsula and strongly influenced by a branch 

 of the warm current "Kuroshio." Animals assembling around the lamp 

 are synecologically classified into the object, fishes, preys, and predators. 

 Reviewing the data obtained during a series of investigations on food 

 habits and behaviors of fishes around the lamp to find the niches of 

 main fishes in lamp-communities, the lamp-animals are classified inta 

 the following five groups: 



1) Prey animals: This group consists of Gammalid amphipods, 

 megalopae, mysids and Engraulis of Shirasu stage, and represents the 

 lowest class in the temporal communities formed artificially under the 

 lamp. It contains no producer or smaller preys nourishing the animals 

 mentioned above. Members of this group are eaten chiefly by the se- 

 condary predators, although a part of them serves as the food of the 

 primary predators. 



2) Primary predators: This group consists of Stolephorus, En- 

 graulis and Pempheris, of which the former two are said to be zoo- and 

 phyto-plankton feeders in the natural environment, but are changed 

 into pure zoo-plankton feeders under the light. Stomachs of the most 

 examined individuals were, however, almost empty. 



3) Secondary predators: This group consists of medium- or large- 

 sized zoo-plankton feeders, e.g. carangids and mackerels. These mem- 

 bers feed chiefly on the prey animals and occasionally on the primary 

 predators. 



4) Tertiary, quaternary and end predators: The primary and se- 

 condary predators which form the chief object of the lamp fisheries are 

 dispersed from the light by the emergence of tertiary and higher pre- 

 dators. Consequently, fishermen hate their visits very much. Espe- 

 cially the end predators, which occupy the highest position in the food- 

 pyramid of the lamp-community, may be called the destroyers of the 

 lamp-community, since the fishes disappear completely at the appear- 

 ance of members of this group. The lower predators form compact 

 shoals and move along the circular rout around the lamp, perhaps along 

 the equi-luminous line, while predators of the higher degree usually 

 visit the lamp in a single individual, move across the equi-luminous 

 line and take food actively under the light. The tertiary predators are 

 composed of squids and Sphyraena, the quaternary predators of Tri- 

 chiurids. The end predators in shallower water are composed of Squa- 

 lus, Coryphaena and Dolphinus, of which the latter two are much 



