If you haven't experienced a dive at dawn to witness this astonishing transformation of the reef and its inhabitants, you owe it to yourself to get up really early one day and do it. Similar progressions, orderly and predictable, occur in the changeover from nocturnal to daytime activities on reefs everywhere. Waking up is apparently triggered for most fish by light intensity, rather than internal clocks according to scientific studies done over the past 20 years. The time for the entire reef to awaken is much longer, usually almost an hour, well within the limits of a one-tank dive or an easy early morning snorkeling trip. Most damselfish and gobies also prefer daylight.
Some fish attend first to grooming, visiting their neighborhood parasite cleaners.
Depending on the species, early morning is also a time for spawning, but for most daytime fish, the morning hours are largely devoted to feeding. A trumpetfish torpedoes in, seizing a small chromis for breakfast. As with all animal communities, densely packed reef populations follow patterns. Within these patterns, fish strike a tenuous balance between getting enough to eat and avoid being eaten. Dawn is one of the most rewarding times to watch the reef.