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Ocean Watch
By Susan Scott
Monday, September 4, 2000
Labor Day means different things to different people. The holiday was created to honor our country's workers. But since organizers selected the first Monday of September as the official day of rest, Labor Day also came to symbolize the end of summer. Turtles find
propagating
hard laborTo me, whose mother went into labor one long-ago Labor Day, subsequently producing a baby brother, Labor Day is a reminder of the pain most women endure to give life to their children.
Reproductive laboring is not restricted to humans, of course, nor even to females. Some marine animals labor in extraordinary ways to perpetuate their species.
Consider octopuses, which get only one chance to do it right. A male octopus becomes sexually mature when he is a year or two old. At that time, he seeks out a receptive female into which he delivers his packet of sperm.
Having completed the one big job of his life, he dies.
Female octopuses don't have it any better. After fertilization the female lays her eggs, then guards and tends them. The mother octopus stops eating during this period and dies when the youngsters are safely hatched.
This one-time, all-out reproductive burst is controlled in both male and female octopuses by two round glands located near their optic tracts. When researchers remove these glands in brooding females, they leave their eggs, resume eating and live a longer life.
At the other end of the extreme are Hawaii's green sea turtles. During a life span that may last 60 years or more (no one knows exactly), a normal female turtle produces thousands of eggs, sometimes laying up to five clutches of about 100 eggs each in just one season.
But before the females get to lay those eggs, most must swim about 500 to 800 miles, one way, through open ocean to the northwest islands of French Frigate Shoals. This atoll, located in the middle of the Hawaiian Islands National Wildlife Refuge, is the last major breeding site for Hawaii's green turtles. Because the turtles' feeding grounds are in the main islands, reproducing for Hawaii's greens requires first a long, rough journey.
Another form of labor for female turtles is getting their eggs fertilized. Ardent males often hang onto the backs of females turtles for hours, forcing them to swim around with the free-loading inseminators on their backs.
Little wonder females reject all suitors after laying that first clutch of eggs.
Once fertile and in the atoll, a female turtle then must crawl high up a sandy beach and then haul herself around to search for a suitable nesting spot.
This moving about on land is difficult for an animal with flippers more suited for swimming than walking.
The turtle drags her heavy body through the sand one lunge at a time, then often spends hours or even entire nights looking for that perfect place.
When she finds it, the turtle painstakingly digs a hole with her rear flippers, scoop after scoop, until finally, it's deep enough to deposit her eggs.
I was once lucky enough to watch this remarkable event and it is intense labor indeed. Female green turtles' reproductive effort is so energy-sapping that they take two to five years off before migrating north to do it again.
This Labor Day I'm appreciating a day off and celebrating the end of a memorable summer.
But I'm also remembering all the moms and dads in the world, human and non, who work so hard for their offspring.
Parents, have a restful day.
Marine science writer Susan Scott's Ocean Watch column
appears Mondays in the Star-Bulletin. Contact her at honu@aloha.net.
