The epigonal is the last immune organ to develop. Granulocytes appear within the genital ridge by week 8. The source unit consisted of a signal generator and a power amplifier. The signal generator produced the wave form, frequency, and voltage. A 60-Hz sine wave and DC pulse electric fields were chosen.
All sharks swam close to the sides of the tank when the signal generator was off.
When the 60-Hz sine wave and DC pulse electric fields were being produced, two species, C. falciformis and T. obesus, immediately turned round. Many turns of the sharks were associated with the DC pulse electric fields. Conversely, G. cuvier and S. fasciatum did not change thier swimming patterns when the signal generator was on. Hence, the behavioral response patterns were different among the species.