Date of Award


Degree Type


Degree Name


Degree Program

Biological Sciences


Biological Sciences

Major Professor

Grady, James

Second Advisor

Cashner, Robert

Third Advisor

Johnson, Steve


Predators select for defensive adaptations, such as stings, toxins, and camouflage color patterns. Madtoms, Noturus, are diminutive catfishes with dorsal and pectoral stings. Thirteen of the 25 nominal species have serrated spines in the pectoral sting and a contrasting pigment pattern. Behavior of two saddled species, N. miurus and N. hildebrandi, and one uniformly colored species, N. leptacanthus, was investigated to test if the pigment pattern is camouflage. Saddle spacing and crypticity of the saddled species were measured against various substrates and were found to be unevenly spaced, which could be camouflage when viewed against gravel. Given substrate choices, madtoms preferred gravel during daylight conditions. In subsequent experiments, all species were given colored gravel to test color vs. texture-based substrate choice and preferred dark substrates. In the presence of a predator stimulus, madtoms preferred gravel at night and dawn. The pigment pattern likely is camouflage when viewed against gravel substrates.


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