Meeting Abstract

36.5  Monday, Jan. 5  Antipredator startle signal of the California spiny lobster (Panulirus interruptus) STAATERMAN, Erica R.*; CLAVERIE, Thomas; PATEK, Sheila N.; Univ. of California, Berkeley; Univ. of California, Berkeley; Univ. of California, Berkeley estaaterman@berkeley.edu

Acoustic antipredator signals are ubiquitous, yet we have little understanding of their effectiveness and behavioral deployment specifically in the marine environment. Some prey produce warning signals to prevent attack from predators, while others use acoustic signals to startle a predator after the attack has begun. We examined the antipredator rasp sound generated by the California spiny lobster (Panulirus interruptus). Using a pole apparatus equipped with a low-light camera and hydrophone, we presented either a model fish (predator), model lobster (conspecific), or pole (control) to spiny lobsters at Santa Catalina Island, during the day and night, in the field and in controlled tank conditions. In addition, we hand-held lobsters at varying distances from a hydrophone and measured the attenuation of the rasp sound. The behavioral trials showed that when the intruder did not touch the lobsters, they rasped in only 18% of the trials, whereas they rasped in 56% of the trials when there was contact (X2=10.8, df=1, p=0.001). Physical contact and behavioral response were also significantly correlated; lobsters exhibited a tail flip escape response in 95% of the physical contact trials (X2=47.7, df=3, p<0.001). The intruder type and direction of approach had no significant effect on lobster behavior or rasping. In the acoustic tests, the average dB level of the rasp relative to the background noise ranged from 1.8 dB at 50 cm to 1.0 dB at 200 cm; thus, the sounds attenuate minimally and remain obscured within the loud background noise. Both the acoustic and behavioral results indicate that the spiny lobster rasp is likely to be used in close range to startle attacking predators.