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The University of Michigan Biological Station (UMBS) was founded in 1909.

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Rusty Crayfish Use Multiple Sensory Cues to Assess Predatory Threats

Aquatic
Organismal
aquatic ecology
behavioral ecology
predator-prey interactions
Project Abstract: 
Predator presence can have a multitude of non-consumptive effects, such as altering how they use shelters, changing their foraging strategies, altering morphological characteristics, or influencing birth rates. Crayfish have been found to alter their behaviors as the size of a predator changes in relation to the focal animal’s size. Recently, studies have shown that crayfish alter foraging and sheltering behavior based on the size of the predator when exposed to chemical cues. These recent studies have not investigated predation rates, or the influence of the predator being physically present. This study exposes rusty crayfish (Faxonius rusticus) to a control, the odor of a largemouth bass (Micropterus salmoides), or a physically present largemouth bass. In experimental trials, crayfish and bass were paired based on their gape ratio. Shelter usage and preference of crayfish was examined to show how they assessed risk in each of the situations. The goal of this study is to give a clear understanding of the ability of crayfish to assess the threat of the predator based on its size when exposed to its odor and/or physical presence.
Investigators: 
GaigeS
pmoore
Status of Research Project: 
Active
Years Active: 
2024
Methods: 
Cinder Blocks will frame 8 mesocosms (160 X 40 X 24), which will be lined with plastic sheeting (Wood et al.). 4 of these mesocosms will have 2 sections (80 X 40 X 24), a predator (Micropterus salmoides) and prey (Faxonius rusticus). The separate sections will give the crayfish no way of seeing the predator. The other 4 mesocosms will have 1 section with both predator and prey within. In these mesocosms, the crayfish will be exposed to both visual and chemical cues from the predator. Control trials will be run with no predators in the mesocosm.In all 8 mesocosms we will place 4 different types of shelters, in the crayfish section, randomly arranged, the shelters will be 1,2,3, and 4 openings. This will allow us to analyze if shelter preference changes as a response to different predator cues. Crayfish and bass will be size matched to give us a wide array of gape ratios (gape of bass : width of crayfish carapace). Above each mesocosm will be a DVR camera to record the crayfish behavior for 24 hours, for each trial. The bass will be fed crayfish pellets, which will be made from grinding dead crayfish in a blender, and freezing. The river water will have enough detritus to provide the crayfish with food.