Meeting Abstract

1.2  Wednesday, Jan. 4  The kinematic basis for the evolution of zooplankton feeding in haemulid fishes FULLER, P. O.*; TAKADA, T.; OUFIERO, C. E.; WAINWRIGHT, P. C.; Univ. of California, Davis

Zooplankton prey are small, difficult to detect, and often evasive; therefore, reef fishes relying on midwater zooplankton for food require specific adaptations to overcome the difficulty of catching enough zooplankton to survive. Three closely related Caribbean reef fishes in the genus Haemulon were filmed in the lab to identify how feeding mechanics differ for fish specializing on zooplankton. These taxa represent an evolutionary transition to diurnal zooplankton feeding: Haemulon vittatum feeds on midwater zooplankton during the day, while H. striatum and H. aurolineatum feed on benthic invertebrates at night. In the lab, strike kinematics from each species feeding on small fish prey were captured from a lateral view with high-speed video recorded at 1000 Hz. Feeding sequences of juvenile specimens were recorded from 7 H. vittatum, 10 H. striatum, and 10 H. aurolineatum specimens (270 sequences total). Eleven landmarks from the video sequences were tracked digitally to measure timing, strike distance, and cranial kinematics during prey capture. Preliminary data from 57 sequences suggest that H. aurolineatum and H. striatum share similar feeding kinematics, while the planktivorous H. vittatum differs only in having greater jaw protrusion coupled with a faster jaw protrusion speed. Greater jaw protrusion projects the predator’s mouth and suction field closer to the prey without increasing the disturbance caused by forward body motion. Therefore, the strike pattern of H. vittatum may be adaptive by decreasing the time during which evasive zooplankton can detect movement and escape. Morphology and feeding performance on zooplankton prey will also be discussed.