Jordan's rule

Jordan's rule is an ecogeographical rule named after the father of American ichthyology David Starr Jordan describes the inverse relationship between water temperature and meristic characteristics. The most common found relationship is for fin ray, vertebrae, or scale numbers to increase with decreasing temperature.

Jordan's rule

Jordan's rule is an ecogeographical rule named after the father of American ichthyology David Starr Jordan describes the inverse relationship between water temperature and meristic characteristics. The most common found relationship is for fin ray, vertebrae, or scale numbers to increase with decreasing temperature.