of or possessing a tail in which the vertebral column turns upwards and extends into the upper, usually larger, lobe, as in sharks
Compare homocercal
Word origin
C19: from hetero- + Greek kerkos tail
heterocercal in American English
(ˌhɛtərˌoʊˈsɜrkəl)
adjective
designating, of, or having a tail fin in which the upper lobe is larger than the lower and contains the upturned end of the spinal column, as in certain fishes, esp. sharks