Fatal penetrating skin ulcers in laboratory-reared octopuses

Young Octopus joubini and O. briareus (35 to 60 days old) that were being reared in high-density groups for biomedical studies developed skin ulcers, whereas octopuses reared in individual containers in the same culture system were disease-free. The ulcers first affected the epidermis of the mantle, and then penetrated downward through the dermis and underlying muscle tissue. Four stages of ulceration were observed. Untreated octopuses with ulcers always died, usually within 4 days. Five species of bacteria were isolated from ulcers: Vibrio alginolyticus, V. damsela, Pseudomonas stutzeri, and Aeromonas caviae from O. joubini; and V. parahaemolyticus, V. damsela, and P. stutzeri from O. briareus. Bacteria were found during all stages of the ulceration. Healthy O. joubini were infected experimentally with four species of bacteria, and V. alginolyticus produced skin ulcers within 2 days. The ulceration was treated with nifurpirinol, and complete healing of the skin occurred within 2 months. The ulcers were probably species-specific because O. maya and O. bimaculoides that were reared in the same culture systems were not affected. The cause of the ulceration was probably an increase in contact among crowded octopuses that produced skin abrasions which were invaded by opportunistic bacteria.