Meeting Abstract

P1.62  Sunday, Jan. 4  Scraping and sucking: Does morphology determine performance in two species of suckers? O’NEILL, M. W.*; GIBB, A. C.; Northern Arizona University; Northern Arizona University mwo@nau.edu

The co-occurring desert and Sonora suckers show distinct morphological and behavioral traits that yield predictions for feeding behavior. Desert suckers have a broad mouth and a cartilaginous plate that appears specialized for scraping attached algae, and Sonora suckers have a smaller gape that may produce effective suction when capturing small invertebrates. Gut content studies suggest that Sonora suckers feed more on insect prey and desert suckers feed more on algae, and this is further supported by stable isotope analysis, where Sonora suckers have a higher nitrogen signal — which indicates a higher proportion of animal tissue in the diet — but both species feed on algae and invertebrates. This raises the question: are aspects of feeding behavior in each species modified to enhance performance on particular prey items, perhaps reducing competition or partitioning food resources? In the laboratory, we examine the performance of each species on a variety of elusive and non-elusive prey types to answer the following specific questions: (1) Are Sonora and desert suckers able to capture the same prey items? (2) Are desert suckers more effective at scraping algae? (3) Do Sonora suckers use suction when capturing insect prey? Preliminary data for both species suggest that they will take prey on the bottom, but not in the water column — which suggests that only benthic insects are likely to be included in the diet in the wild. Ongoing experiments will examine the ability of each species to remove encrusting material from the substrate by scraping and procure food from the substrate by suction.