FISHERY BULLETIN: VOL 72, NO. 4 



3) Panulirus interruptus 



Two of the aggressive postures 

 described by Roth (1972) were used 

 in this study. These aggressive pos- 

 tures are body raise and rear-up. 

 We observed that these are the 

 most common and morphologically 

 distinct aggressive postures ex- 

 hibited by P. interruptus. 



a) Body raise — Raising the body 

 off the substrate by partial 

 extension of the walking legs. 

 This corresponds to Roth's term 

 Rise Up (Ri). 



b) Rear-up — Raising the body off 

 the substrate by full extension 

 of the third, fourth, and fifth 

 walking legs. The anterior part 

 of the body is raised much 

 higher than the posterior part 

 of the body. This was also 

 called Rise Up by Roth (R2 

 and R3). However, we have 

 combined his R^ and R3 into a 

 separate category, rear-up, 

 because they appear to be dif- 

 ferent intensities of the same 

 behavior action pattern, which 

 is distinct from Ri . 



C) Attack 



1) Homarus americanus and Cancer 

 antennarius 



Four actions were included under 

 attack. These were pinch, push, 

 scissoring, and chase. 



a) Pinch — Rapid gripping and re- 

 lease of any part of a Cali- 

 fornia spiny lobster's body 

 with one or both chelipeds. 



b) Push — Contact between the 

 chelipeds and any part of a 

 California spiny lobster's body 

 when the chelipeds are thrust 

 forward while the body remains 

 stationary or the chelipeds are 

 extended or in a meral spread 

 in a stationary position during 

 locomotion. 



c) Scissoring — As described by 

 Schrivener (1971) for//, ameri- 

 canus, "This occurs when one 

 lobster faces its opponent, with 



the chelae in the meral spread 

 posture (spread wide apart, 

 long axes of the palms point- 

 ing at the adversary). The 

 chelae are then rapidly brought 

 together in a scissoring motion. 

 As a result, they either strike 

 or pass rapidly in front of the 

 other animal." 

 d) Chase — During chase the actor 

 moves rapidly toward a hetero- 

 specific that in turn is usually 

 moving rapidly and is ob- 

 viously trying to remove itself 

 from the vicinity of the lobster 

 following it. Chase was re- 

 corded only after the actor 

 and reactor had been within 30 

 cm from one another. Frequent- 

 ly, chase precedes a push or 

 pinch and follows an initial 

 lunge by an actor towards the 

 reactor. During chase//, amer- 

 icanus usually displays meral 

 spread. 

 2) Panulirus interruptus 



Two actions were included under 

 attack. These were physical con- 

 tact and chase. 



a) Physical contact — This in- 

 volves colliding with some part 

 of a heterospecific's body; in 

 some cases clasping of the op- 

 ponent with the first three 

 pairs of walking legs or a bite 

 may occur. This includes Roth's 

 (1972) low intensity attack 

 (Ai), high intensity attack 

 (A2), and clasp (CD. 



b) Chase — Rapid locomotion to- 

 ward a reactor while it is 

 removing itself from the vicin- 

 ity of the lobster following it. 



D) Social contact — Two heterospecifics 

 were recorded as having social con- 

 tact when one of the following events 

 occurred. 



1) Two or more heterospecifics came 

 within 30 cm of one another during 

 movement about the tank without 

 aggressive interaction occurring. 

 This category was recorded 



1150 



