Clown anemonefish live among the stinging tentacles of Pacific anemones, which protect them from predators. The anemonefish are either immune to these stings or somehow inhibit them. In return for this safe haven, anemonefish chase predators away from the anemone.

Coral reefs are magnets for life. In otherwise open water, they provide hard surfaces for animals to cling to and countless nooks and crannies for others to live in.

Coral reefs provide food as well as habitat. Algae grow on sunlit surfaces, providing food for plant-eating animals. Predators come to eat these animals, and both provide nutrient-rich feces, fertilizing the surrounding waters.

The rich variety of habitats and intense competition for space have led to a staggering diversity of species, each adapted to life on the reef in a particular way. The constant flux caused by storms and hurricanes also promotes diversity - in a more stable habitat, a few species might dominate the reef and exclude all others.

In this densely packed community, many animals live on, or even inside, other animals. The internal cavities of corals and sponges, for example, are filled with worms, mollusks, crustaceans and even fish.

Night Shift

Bigfin Reef Squid. R. Mickens / AMNH