BEHAVIORAL-RESPONSE OF THE SCYPHOZOAN JELLYFISH AURELIA-AURITA (L) UPON CONTACT WITH THE PREDATORY JELLYFISH CYANEA CAPILLATA (L)

Underwater manipulative experiments were carried out in situ to invest igate the sensibility of the jellyfish Aurelia aurita (L.) to contact with the tentacles of Cyanea capillata (L.), commonly known as a preda tor on A. aurita. Movements of individual medusae touched by tentacles of C. capillata and other objects were video-recorded during SCUBA di ves. The behavioural variable studied was change in swim pulse frequen cy. The results showed that A. aurita was highly susceptible to the te ntacles of C. capillata and responded with an increased swim pulse fre quency when touched at the umbrellar margin but not at the central exu mbrella. Contact with other objects also induced a behavioural respons e in A. aurita.