Leptodora kindti (Crustacea: Cladocera) is a large species of zooplankton (2-18 mm length) that is exceptionally transparent. This transparency is believed to be a means by which it successfully coexists in lakes with planktivorous fishes. We investigated the gut remains of bluegill (Lepomis macrochirus) that had been feeding on L. kindti and Daphnia (D. galeata and D. retrocurva) in the wild (Lake Zurich, Illinois) and found that bluegill readily preyed on L. kindti as small as 3-5 mm length, and strongly selected L. kindti over Daphnia galeata and Daphnia retrocurva. The large compound eye of L. kindti is one half to one complete order of magnitude larger than Daphnia's eye, consistent with the hypothesis that eye area is an important visual cue for fishes. Moreover, the slope of the relationship between eye area and body length is an order of magnitude shallower in L. kindti than Daphnia, suggesting that eye area has been under stronger negative selection in L. kindti. Results suggest that L. kindti's large and dark eye compromises the transparent nature of its body.
Bibliographical noteFunding Information:
We are grateful to Dennis Abbott and Sal Masella of ‘Bill’s Boats’ in Lake Zurich, Illinois, who generously provided a boat and field assistance during this study. This work was supported in part by a grant from the College of Liberal Arts and Sciences at DePaul University to D. K. Branstrator.
- Body transparency
- Fish planktivory
- Leptodora kindti