Fig. 5. Obligate coral dwellers represented by Gobiodon axillaris (A, left, B), Paragobiodon xanthosomus (A, middle), Caracanthus unipinna (A, right), and Gobiodon histrio (C). These fishes spend virtually their whole life between branches of coral, and show a high degree of hypoxia tolerance. Moreover, G. axillaris, G. histrio and C. unipinna have excellent abilities for air breathing, apparently through their scaleless skin. Air breathing is needed if their coral home becomes air exposed. C shows G. histrio in a coral colony that has become air exposed during a nocturnal low tide at the Lizard Island reef. Photos by G. E. Nilsson.