Published online by Cambridge University Press: 06 October 2009
Spinal cords in deep sea fishes of 37 families have been examined for the presence and relative size of Mauthner axons. No correlation has been found between fish size, and the relative diameter of the Mauthner axon in different species. However, counts of primary motoneuron number and myotomal muscle fibre number in each segment suggest that Mauthner axon diameter is related to the numbers of these in each segment. The behavioural role of the Mauthner system is discussed, and it is concluded that in certain elongate-bodied fishes such as halosaurs and macrourids, a C-type startle response is unlikely.