SUNFISH

A redbreast sunfish, Lepomis auritus

I began working with sunfish during my PhD with Tim Higham. During that work we developed a few new approaches for understanding how to quantify the interactions between swimming and feeding, whether this integration changes depending on what the predator is eating, and how these interactions relate to success during prey capture. To do this, we needed a group of model fishes where we already had a good understanding of how swimming and feeding work, individually. That's where the freshwater sunfishes and basses (Family Centrarchidae) came in.

Several species have been used to understand how fins work, how muscles work, how jaws work, and how suction works (among other things), creating a strong foundation to build on. Their strong reliance on suction to pull prey into their mouth is particularly interesting since this only works at close distance and for a short time period. This means that coordination with swimming is important for making sure the suction volume is in the right place at the right time. There was also already evidence from Tim's PhD work that this integration existed.

A bluegill capturing prey by coordinating swimming and feeding movements

Using bluegill, green sunfish, and largemouth bass, we built a mathematical model to predict the suction volume during prey capture and showed that there are differences in predator accuracy between species and across prey types (see the paper here). We also looked closer at bluegill, and found that they do not change how they integrate feeding and swimming across these prey types. Instead, individuals seem to be different in how they integrate these behaviors (see the paper here). These results are beginning to give us insight into the ways that animals can differ in how they integrate feeding and swimming tasks, and the consequences that integration can have on success at varying levels.

Together, this work shows that there is important variation in prey capture behaviors within and among species that has consequences for how these animals interact with their environment. Also, since we found variation in integration among individuals from the same population, it is possible that integration between feeding and swimming may be a trait that ecological selection could act on. If this is supported with further work, it means that integration, and interactions across major functional systems, could be a significant driver of adaptation and evolution in these and other fishes. Studies on feeding and/or swimming often mention that interactions with other traits or functions could be important for driving patterns in the trait of interest, but they don't often study those interactions explicitly.

Work in the lab continues to build on these ideas using several species of sunfish to further understand several main questions:

How do the underlying physiological processes driving feeding, swimming, and integration interact to produce the behaviors we measure?
How does the variation in these behaviors affect ecological interactions with other organisms (prey, predators, competitors, humans, etc.) and their survival in varying environments?
How do these behaviors, and their effects on survival, shape long-term patterns of persistence and diversification?

A flier, Centrarchus macropterus. They don't fly, but they can swim fast.