Meeting Abstract

P2.131  Jan. 5  Acoustic mechanics of stick and slip friction in California spiny lobsters (Panulirus interruptus) BAIO, J.E.**; SERAFIN, S.; PATEK, S.N.; Univ. of California, Berkeley; Institute of Media Technology and Engineering, Aalborg Univ. Copenhagen; Univ. of California, Berkeley joebaio@berkeley.edu

Sound production in spiny lobsters (Palinuridae) is characterized as a stick and slip friction mechanism similar to that of bowed stringed instruments. Spiny lobsters generate sound by rubbing a plectrum (an extension off each antenna) against a file (located on both sides of a plate beneath the eyes). However, the parameters that influence stick/slip dynamics in spiny lobsters have yet to be explored. Using audio recordings, high speed videography and force sensors, we measured the acoustic, kinematic, and frictional parameters of sound production in the California spiny lobster (Panulirus interruptus). Understanding how these parameters correlate with each other, specifically, how the frictional force varies with velocity of the plectrum, provides a starting point for modeling these acoustic signals. The average and peak velocities of the plectrum slipping over the file were 11.0 � 4 cm/s and 23.0 � 5.3 cm/s, respectively. Frictional forces were measured by mounting the plectrum and file on orthogonal force beams incorporated into a linear translation apparatus that simulated the natural movement of the plectrum over the file. The periodicity of the resulting force traces (94.9 � 14.7 pulses/s), a cyclical pattern of the stick/slip pulses, was consistent with the period of the resulting acoustic pulses (87.6 � 15.9 pulses/s). Additionally, these traces also provided measurements of the coefficients of static and kinetic friction. These experimentally determined parameters along with an understanding of how they influence the production of acoustic signals will ultimately be exploited to model evolutionary variation in stick and slip sound production across spiny lobster species.