Table 1. Parameters used to calculate a dominance index (DI) for each individual tested in the pair interactions.

Parameter	Level
Movement toward or away from each other
Rush toward other prawn while facing it	6
Walk toward other prawn while facing it	5
Turn toward other prawn but not walking to it	4
Turn away from facing other prawn, without walking away from it	3
Walk away from other prawn while facing it	2
Walk away from other prawn without facing it	1
Rush to move away from other prawn without facing it	0
Abdomen posture
Fully flexed	6
Partially flexed	4, 5
Extended (horizontally)	3
Partially hyperextended	1, 2
Fully hyperextended	0
Position of body and walking legs
Legs fully flexed/body touching bottom	0, 1
Legs partially flexed/body partially lifted	2, 3, 4
Legs fully extended/body fully lifted	5, 6
Movement and position of claws
Crossed in front of eyes	0
Touching bottom while extended	1
Touching bottom while flexed	2
At body level	3
Above body level	4
Extended at or above body level	5
Quickly thrust forward	6
Used for lifting the other prawn	6
Movement of chela
Closed/not touching other prawn	0
Closed/touching other prawn	1
Open/not touching other prawn	2
Open/touching other prawn	3
Scissoring in front of other prawn	4
Open, grabbing other prawn	5
Nipping or tearing	6

The values in the Level column indicate the weight or level of the parameter as an indicator of dominance/subordination, 6 indicating the most highly dominant behavior, 0 indicating complete or total subordination. These parameters are based on those used by Barki and colleagues (1992) with the following modifications: (1) a more detailed specification of levels or weights by describing in words what each whole number in the scale represents; (2) subdividing the parameter of claw movement into the two parameters“movement and position of claws” and “movement of chelas”; and (3) changing the scale from one that included negative numbers (−3 through +3) to one with only positive numbers (0 through +6).