Ocean Watch

Friday,  January 30, 2004

While watching "Finding Nemo" on DVD this week, I wondered how kids took that opening scene of a barracuda eating alive a clownfish mother and all but one of her unborn children. I mean, those hunters shooting Bambi's mother sent millions of us boomers to shrinks for years.

OK, maybe blaming Walt for our neuroses isn't fair, but the death of that deer did disturb me.

Even though kids today are far more accustomed to movie violence than we were back then, Nemo screenwriters might still have softened the blow. For instance, after Nemo's mom got eaten, they could have had Nemo's dad undergo a sex change and become Nemo's new mom. This former dad/current mom would then choose a new husband from the ohana and each month produce a few thousand siblings for Nemo.

That story line might sound too mature for 5-year-olds, but when I tell kindergartners that this happens in real life, they think it's cool. And it is. Clownfish didn't need "Finding Nemo" to be admired. They're stars on their own.

A typical clownfish family consists of a monogamous male and female and several unrelated juveniles, all living together inside an anemone.

Although there are occasional crossovers, each species of clownfish (there are 28) prefers a certain species of anemone. Large anemones often host more than one fish family, but not usually more than one species.

About once a month, the clownfish couple cleans growth off a rock near or under their anemone home. On this bare spot, the female lays from several hundred to several thousand eggs.

The male fertilizes these eggs and then guards them from predators. Males also fan the eggs to keep plants and animals from settling on them.

After about a week of this, the tiny clownfish larvae hatch. Unlike Nemo, real clownfish babies drift along as plankton, never seeing their parents again. Sixteen days later the youngsters settle down inside an anemone of their own or inside one already hosting members their own species.

Clownfish are immune to anemones' stings, but because other fish are not, the anemone acts like a club-wielding bodyguard. In an aquarium, clownfish don't need anemones to survive, provided fish-eaters don't share the tank.

Clownfish must have anemones to live, but anemones don't need clownfish at all.

Such a relationship -- where one organism benefits from a relationship with another, but the other is neither helped or harmed -- is called commensalism.

Hawaii has no clownfish because all our anemones are tiny.

Now, about dad becoming mom. All clownfish are born as males with the ability to become females if necessary. So if, say, a barracuda eats the female of a pair, the male turns into a female. A juvenile in the home anemone then matures and moves up to the dad position.

The presence of a healthy pair of adults stunts the growth of the remaining juveniles. These Peter Pan fish never grow up unless nature presents a pressing need.

Living in hideouts, changing sex, never growing up ... The real clownfish lifestyle would make a fine film -- and kids would love every minute.