Polymorphic populations are often considered as intermediate stages of speciation. Bluegill sunfish (Lepomis macrochirus) from Lake Waban, Wellesley, MA have diverged into two ecomorphs based on their diet, occupied habitat and morphology. Littoral bluegills are generalist feeders that consume a variety of aquatic invertebrates. Pelagic bluegills feed primarily on Daphnia. We aimed to understand if suction pressure generation, prey capture behaviors and pharyngeal jaw morphology differed between the littoral and pelagic ecomorphs feeding on three prey types. Littoral and pelagic bluegills showed similar feeding kinematics and peak pressure, however, significant differences were observed among prey types within an ecomorph. Feeding events on brine shrimp were slower and accompanied by less negative pressure for both ecomorphs. Littoral bluegills varied their use of ram among prey types, however, pelagic bluegills (zooplankton specialists) did not. Similar to previous studies, when presented with different prey items both dietary generalists and specialists varied equally in most aspects of their feeding behaviors. However, pelagic bluegills (dietary specialists) did not vary in their approach behaviors. Despite the lack of differences in trophic morphology among the individuals sampled here, the prey approach behaviors of dietary specialists appears to be fixed in pelagic bluegills. This result deemphasizes the importance of suction during feeding and places more importance on prey approach behaviors.

Temperature can have profound impacts on fitness‐related activities in fishes. Feeding is an ecologically relevant task which is controlled by muscle function. Consequently, in ectotherms, muscle function and feeding kinematics can be altered by temperature. This study investigated the effect of decreasing temperature on the feeding kinematics of the northern most labrid in the Western Atlantic. During winter, cunner (Tautogolabrus adspersus) enter a state of extended torpor in order to conserve energy when water temperatures drop below ~10°C. We hypothesized that feeding kinematics would be slower at lower temperatures especially those associated with torpor (≤10°C). Additionally, we hypothesized that prey type will elicit different feeding behaviors. Feeding events on sandworms and Asian shore crabs were recorded at 5, 10, 15 and 20°C. Fish held at 5°C had slower opening and closing jaw velocities while using more ram than the other temperature treatments. No differences were detected between prey types. For both prey types, the temperature treatment which consistently induced torpor (5°C) slowed oral jaw movements, which likely forced cunner to rely more on ram than suction to capture prey. Torpor temperatures appeared to have less of an effect on feeding than on metabolic rate, steady swimming capabilities and muscle function, suggesting some compensatory mechanisms of feeding musculature in cunner.