So a star was born. Finding Nemo, the Pixar movie Stanton wrote and directed, won the 2003 Academy Award for best animated feature and remains one of the highest grossing G-rated films of all time, taking in over $850 million to date. Nemo—a clownfish of the species Amphiprion percula—introduced millions of children around the world to a wondrous tropical ecosystem: the coral reef and its denizens.
Clownfish get their name from the bold color strokes on their body (from rich purplish browns to bright oranges and reds and yellows), often divided by stark lines of white or black, quite like the face paint on a circus clown. Seeing clownfish darting among the tentacled folds of an anemone is like watching butterflies flitting around a flowering plant in a breeze-blown meadow—mesmerizing.
Twenty-nine species of clownfish live among the reefs from East Africa to French Polynesia and from Japan to eastern Australia, with the greatest concentration of diversity on the north coast of New Guinea in the Bismarck Sea (where with a little luck and a competent guide you can see seven species on one reef). On a recent diving trip to Fiji, Gerald Allen—a research associate at the Western Australian Museum and the world's clownfish authority—discovered the 29th species, Amphiprion barberi. That brought his lifetime total to seven clownfish (and nearly 500 species of reef fish). "I still get a huge buzz when I find something new," Allen says. "Amphiprion barberi is a beautiful clown, orange and red like a blazing ember on the reef."
Among scientists and aquarists, clownfish are also known as anemonefish because they can't survive without a host anemone, whose stinging tentacles protect them and their developing eggs from intruders. Of the roughly thousand species of anemones, only ten host clownfish. It's still a mystery exactly how a clownfish avoids being stung by the anenome, but a layer of mucus—possibly developed by the clownfish after it first touches an anemone's tentacles—may afford protection. "It's a slime that inhibits the anemone from firing off its stinging cells," Allen says. "If you ever watch a new little anemonefish coming into an anemone, it makes these very tentative touches. They have to make contact to get this chemical process going." Thus shielded, the clownfish, in effect, becomes an extension of the anemone—another layer of defense against anemone-eating fish, such as the butterflyfish. What's good for the clownfish is good for the anemone, and vice versa.
Clownfish spend their entire lives with their host anemone, rarely straying more than a few yards from it. They lay their eggs about twice a month on the nearest hard surface concealed by the fleshy base of the anemone, and they aggressively protect the developing embryos. Just after a clownfish hatches, it drifts near the surface for a week or two as a tiny, transparent larva. Then it metamorphoses into a miniature clownfish less than half an inch long that descends to the reef. If the young fish doesn't find an anemone and acclimatize to its new life within a day or two, it will die.